BEGIN:VCALENDAR
PRODID:-//eluceo/ical//2.0/EN
VERSION:2.0
CALSCALE:GREGORIAN
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1032
DTSTAMP:20230914T125947Z
SUMMARY:Online Parameter Estimation for Human Driver behavior Prediction fr
 om Driving Demonstration Data
DESCRIPTION:Speaker: Raunak P. Bhattacharyya (Stanford University\, USA)\n\
 nAbstract: \nAbstract: Driver models are invaluable for safety validation 
 in simulation. However\, driver modeling is characterized by a high degree
  of uncertainty. While rule-based driver models have the advantage of bein
 g interpretable and collision-free\, black-box models are more expressive 
 than rule-based models and capture more nuanced behavior. Unfortunately\, 
 such black-box models lack interpretablity and fail to incorporate the saf
 ety guarantees of the rule-based models. While most approaches in driver-m
 odeling literature select model parameters offline\, online estimation has
  the advantage of being able to capture the behavior of individual drivers
 . In this paper\, we show that online parameter estimation applied to the 
 Intelligent Driver Model captures nuanced individual driving behavior whil
 e providing collision free trajectories. We benchmark performance against 
 rule-based and black-box driver models on two real world driving data sets
 . We evaluate the closeness of our driver model to ground truth data demon
 stration and also assess the safety of the resulting emergent driving beha
 vior.\n
URL:https://www.tcs.tifr.res.in/web/events/1032
DTSTART;TZID=Asia/Kolkata:20200102T143000
DTEND;TZID=Asia/Kolkata:20200102T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1033
DTSTAMP:20230914T125947Z
SUMMARY:Workshop on Learning Theory 2
DESCRIPTION:Speaker: \n\nAbstract: \nThe field of Learning Theory has witne
 ssed an explosive growth over the past decade. This growth has been made p
 ossible by exciting developments in the fields of applied mathematics\, st
 atistics and computer science and fueled by the need for processing modern
  large data sets.\nThis two-day workshop seeks to explore some aspects of 
 statistical learning theory.  It will include five mini-courses and featu
 re a couple of talks.\nParticipation is by invitation only.  Please conta
 ct learningtheory@tifr.res.in for further information.\n
URL:https://www.tcs.tifr.res.in/web/events/1033
DTSTART;TZID=Asia/Kolkata:20200103T090000
DTEND;TZID=Asia/Kolkata:20200104T173000
LOCATION:AG-66 (Lecture Theatre)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1034
DTSTAMP:20230914T125947Z
SUMMARY:Bombay Information Theory Seminar 2020
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1034
DTSTART;TZID=Asia/Kolkata:20200106T090000
DTEND;TZID=Asia/Kolkata:20200109T170000
LOCATION:TIFR and IIT Bombay
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1035
DTSTAMP:20230914T125948Z
SUMMARY:Testing Noisy Linear Equations for Sparsity
DESCRIPTION:Speaker: Anindya De (University of Pennsylvania\nUnited States)
 \n\nAbstract: \nAbstract: Consider the following basic problem in sparse l
 inear regression -- an algorithm gets labeled samples of the form (x\,  +
  \\eps) where w is an unknown n-imensional vector\, x is drawn from a bac
 kground distribution D and \\eps is some independent noise. Given the pro
 mise that w is k-sparse\, the breakthrough work of Candes\, Rhomberg and 
 Tao (2005) shows that w can be recovered with samples and time which scal
 es as O(k log n). This should be contrasted with general linear regressio
 n where O(n) samples are  information theoretically necessary.\nIn this 
 talk\, we look at this question from the vantage point of property testin
 g and study the decision variant of the following question -- namely\, wh
 at is the complexity of deciding if the unknown vector w is k-sparse (or 
 at least say 0.01 far from k-sparse in \\ell_2 distance). We show that th
 e decision version of the problem can be solved with samples which are in
 dependent of n as long as the background distribution D is i.i.d. and the
  components are not Gaussian. We further show that weakening any of the c
 onditions in this result necessarily makes the complexity scale as log n 
 (thus showing our results are tight).\nJoint work with Xue Chen (Northwes
 tern) and Rocco Servedio (Columbia).\n
URL:https://www.tcs.tifr.res.in/web/events/1035
DTSTART;TZID=Asia/Kolkata:20200106T103000
DTEND;TZID=Asia/Kolkata:20200106T113000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1036
DTSTAMP:20230914T125948Z
SUMMARY:Learning and Characterization of Interventional Equivalence class o
 f Causal Graphs with Latents
DESCRIPTION:Speaker: Karthikeyan Shanmugam (IBM Research AI Group\, USA)\n\
 nAbstract: \nAbstract: Directed Causal Graphs (DAGs) capture causal relati
 onships amongst a set of variables and they specify how interventional dis
 tributions relate to observational ones. Unobserved latent variables  are
  represented in DAGs with edges having double arrows. Celebrated``do-calcu
 lus” introduced by Pearl relates invariances in interventional distribut
 ions to a specific causal graph with latents embodying expert knowledge. W
 e consider the reverse problem of learning the equivalence class of causal
  graphs that could imply the observed invariances of the do-calculus. Give
 n observational and interventional data obtained under soft interventions 
 with known targets\, we provide a complete characterization of the equival
 ence class of Causal DAGs. We also provide a sound learning algorithm to l
 earn the equivalence class under additional faithfulness assumptions.\nBio
 :\nKarthikeyan Shanmugam is currently a Research Staff Member with the IBM
  Research AI group in NY. Previously\, he was a Herman Goldstine Postdocto
 ral Fellow in the Math Sciences Division at IBM Research\, NY. He obtained
  his Ph.D. in Electrical and Computer Engineering from UT Austin in 2016\,
  MS degree in Electrical Engineering from USC in 2012\, B.Tech and M.Tech 
 degrees in Electrical Engineering from IIT Madras in 2010. His research in
 terests broadly lie in Graph algorithms\, Machine learning\, Optimization\
 , Coding Theory and Information Theory. In machine learning\, his research
  focus is primarily on causal inference\, online learning and explainable 
 ML. He has also worked on problems relating to information flow\, storage 
 and caching over networks.\n
URL:https://www.tcs.tifr.res.in/web/events/1036
DTSTART;TZID=Asia/Kolkata:20200110T143000
DTEND;TZID=Asia/Kolkata:20200110T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1037
DTSTAMP:20230914T125948Z
SUMMARY:PIDForest: Anomaly detection via Partial Identification
DESCRIPTION:Speaker: Parikshit Gopalan (VMware Research\nPalo Alto\, CA\, U
 .S.)\n\nAbstract: \nAbstract: Anomaly detection is a ubiquitous problem in
  machine learning. Here one is given a large population of points\, we may
  not have much knowledge about their structure a priori. The goal is to fi
 gure out what is "typical" of the datatset\, and what points are atypical 
 or anomalous.  This talk will explore a framework called Partial Identifi
 cation for identifying anomalies in a large datatset.\n\nWe propose a defi
 nition for “anomalousness” that captures the intuition that anomalies 
 are easy to distinguish from the overwhelming majority of points by relati
 vely few attribute values: we call this partial identification. Our notio
 n is inspired by the notion of Partial IDs that were studied by Yehudayoff
  and Wigderson in the context of population recovery. Formalizing this int
 uition\, we propose a geometric anomaly measure for a point that we call P
 IDScore\, which measures for the minimum density of data points over all s
 ubcubes containing the point. We present PIDForest: a random forest based
  algorithm that finds anomalies based on this definition and show that it 
 performs favorably in comparison to several popular anomaly detection meth
 ods\, across a broad range of benchmarks.\n\nBased on joint work with Udi 
 Wieder (VMware) and Vatsal Sharan (Stanford) that appeared in NeurIPS 2019
 .\n
URL:https://www.tcs.tifr.res.in/web/events/1037
DTSTART;TZID=Asia/Kolkata:20200113T143000
DTEND;TZID=Asia/Kolkata:20200113T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1038
DTSTAMP:20230914T125948Z
SUMMARY:Privacy-Preserving Localization and Recognition of Human  Activitie
 s
DESCRIPTION:Speaker: Prof. Janusz Konrad (Boston University\, USA)\n\nAbstr
 act: \nAbstract: Smart rooms\, that respond to occupant behavior\, will l
 ikely become a common occurrence in our lifetimes. With advanced sensors\
 , processors and algorithms\, such rooms are expected to save energy and 
 provide productivity as well as health benefits. Indoor localization of 
 occupants and recognition of their activities are two key components of t
 his vision. However\, traditional camera-based systems may not be accepta
 ble in privacy-sensitive scenarios since high-resolution images may revea
 l room details and occupant identity to eavesdroppers. I will first revie
 w traditional approaches to protecting occupant’s visual privacy\, incl
 uding reversible methods (e.g.\, data scrambling) and irreversible method
 s (e.g.\, optical and digital obfuscation of visual data). Then\, I will 
 describe computational solutions via resolution reduction recently develo
 ped at Boston University. In one approach\, a small network of ceiling-mo
 unted\, single-pixel RGB sensors collects visual data from which occupant
 ’s location is estimated by means of advanced algorithms. In another ap
 proach\, extremely low resolution videos (e.g.\, 16 x 12 pixels) are used
  to recognize occupant’s activities. Finally\, I will discuss visual pr
 ivacy protection by replacing the identity information in a person’s im
 age with another identity by means of variational generative-adversarial 
 networks (VGANs).\nBio: Janusz Konrad received Master’s degree from Tec
 hnical University of Szczecin\, Poland in 1980 and PhD degree from McGill
  University\, Montréal\, Canada in 1984. He joined INRS-Télécommunicat
 ions\, Montréal as a post-doctoral fellow and\, since 1992\, as a facult
 y member. Since 2000\, he has been on faculty at Boston University. He is
  an IEEE Fellow and a recipient of several IEEE and EURASIP Best Paper aw
 ards. He has been actively engaged in the IEEE Signal Processing Society 
 as a member of various boards and technical committees\, as well as an or
 ganizer of conferences. He has also been on editorial boards of various E
 URASIP journals. His research interests include video processing and comp
 uter vision\, stereoscopic and 3-D imaging and displays\, visual sensor 
 networks\, human-computer interfaces\, and cybersecurity.\n
URL:https://www.tcs.tifr.res.in/web/events/1038
DTSTART;TZID=Asia/Kolkata:20200113T160000
DTEND;TZID=Asia/Kolkata:20200113T170000
LOCATION:D-Block Conference Room (D-406)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1039
DTSTAMP:20230914T125948Z
SUMMARY:Solidity+: A Language for Robust Programming of Smart Contracts
DESCRIPTION:Speaker: R.K. Shyamasundar (IIT Bombay\, Mumbai)\n\nAbstract: \
 n"2nd UNESCO World Logic Day Celebration Lecture"\nAbstract: Smart Contra
 cts handle and transfer assets of considerable value. Thus\, it is crucial
  that their implementation be secure against attacks which aim at stealin
 g or tampering the assets. In the recent past\, there have been several a
 ttacks that have exploited existing vulnerabilities in smart contracts. O
 nce a smart contract is up and running\, changing it is very complicated a
 nd nearly infeasible. One of the reasons is that when a contract is create
 d\, it is immutable\; once deployed on the Blockchain it stays there fore
 ver. If we find a defect in a deployed smart contract\, a  new version o
 f the contract has to be created and deployed. When we deploy a new versio
 n of an existing contract\, data stored in the previous contract does not
  get transferred automatically to the  newly refined contract. We have t
 o manually initialize the new contract with the past data which makes it 
 very cumbersome. Similarly\, neither updating a contract nor rolling back 
 an update is possible\; this greatly increases the complexity of implemen
 tation and places a huge responsibility while being deployed initially on
  the Blockchain. We describe the design and use of language Solidity+\, fo
 r programming smart contracts. An important outcome of using of Solidity+
 \, is that brings out an outline of a proof carrying code for the smart c
 ontract for free – needless to emphasize that it is a very welcome feat
 ure for smart contracts on Blockchains.\n
URL:https://www.tcs.tifr.res.in/web/events/1039
DTSTART;TZID=Asia/Kolkata:20200114T143000
DTEND;TZID=Asia/Kolkata:20200114T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1040
DTSTAMP:20230914T125948Z
SUMMARY:Formalizing Finite Set Combinatorics in Type Theory
DESCRIPTION:Speaker: Abhishek Singh\n\nAbstract: \nAbstract: Mathematical p
 roofs when written in conventional ways often contain imprecise definition
 s\, unstated background assumptions\, and inferential gaps in reasoning. I
 n such circumstances\, it becomes difficult for a reviewer to determine wh
 ether the given proof is correct or not.  Even if the theorem statement t
 urns out to be true\, judging it to be so could take a long time. A possib
 le solution to this problem is to formalize mathematical results using Pro
 of Assistants. Proof Assistants are software tools built on top of a small
  and trusted kernel that provides a formal language for writing mathematic
 al statements and their proofs. Hence\, formally verifying a mathematical 
 theory using a Proof Assistant can increase our confidence in the verified
  results. However\, the task of formalizing mathematics using Proof Assist
 ants presents some unique challenges\; both practical as well as theoretic
 al. Theoretical challenges mostly arise because some trivially assumed axi
 oms of classical mathematics may not be provable in the core logic of the 
 Proof Assistant. On the other hand\, the practical difficulties of formali
 zation mostly arise because the machine-checkable proofs are significantly
  more detailed than the corresponding paper proofs. In this talk\, we will
  address both these issues while presenting formal proofs of some key resu
 lts from finite set combinatorics. More precisely\, we present formalized 
 libraries of definitions and results on two important mathematical structu
 res from combinatorics: (i) finite partially ordered sets\, and (ii) finit
 e simple graphs. These libraries have been formalized in the type theory o
 f Coq Proof Assistant.\n
URL:https://www.tcs.tifr.res.in/web/events/1040
DTSTART;TZID=Asia/Kolkata:20200115T113000
DTEND;TZID=Asia/Kolkata:20200115T130000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1041
DTSTAMP:20230914T125948Z
SUMMARY:A Quadratic Lower Bound for Algebraic Branching Programs
DESCRIPTION:Speaker: Prerona  Chatterjee\n\nAbstract: \nAbstract: An Algeb
 raic Branching Program (ABP) is a layered graph where each edge is labele
 d by an affine linear form and the first and the last layer have one vert
 ex each\, called the “start” and the “end” vertex respectively. T
 he polynomial computed by an ABP is equal to the sum of the weights of al
 l paths from the start vertex to the end vertex in the ABP\, where the we
 ight of a path is equal to the product of the labels of all the edges on 
 it. The size of an ABP is the number of vertices in it.\nIn this talk\, we
  will see a proof of the following result. Any Algebraic Branching Progra
 m (ABP) computing the polynomial $\\sum_{i = 1}^n x_i^n$ has at least $\\
 Omega(n^2)$ vertices.\nThis improves upon the lower bound of $\\Omega(n \\
 log n)$\, which follows from the classical result of Baur and Strassen [S
 tr73\, BS83]\, and extends the results in [Kum19]\, which showed a quadra
 tic lower bound for homogeneous ABPs computing the same polynomial.\nThe 
 talk is based on work done with Mrinal Kumar\, Adrian She and Ben Lee Vol
 k.\n
URL:https://www.tcs.tifr.res.in/web/events/1041
DTSTART;TZID=Asia/Kolkata:20200117T160000
DTEND;TZID=Asia/Kolkata:20200117T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1042
DTSTAMP:20230914T125948Z
SUMMARY:Deterministic Representation of Linear Matroids
DESCRIPTION:Speaker: Pranabendu Misra (Max Planck Institute for Informatics
 \nSaarbrucken\, Germany.)\n\nAbstract: \nAbstract: Matroids are combinato
 rial objects that generalize the notion of linear independence. They have
  several applications in design and analysis of algorithms. Linear matroi
 ds are a subclass of matroids that can be represented by a matrix. Recent
 ly\, these matroids have found applications in Parameterized Complexity\,
  including some breakthrough results. In this talk\, we will discuss the 
 problem of constructing a matrix representation of linear matroids\, espe
 cially via deterministic algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1042
DTSTART;TZID=Asia/Kolkata:20200121T143000
DTEND;TZID=Asia/Kolkata:20200121T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1043
DTSTAMP:20230914T125948Z
SUMMARY:Ultra Large-scale Linear Programming based on Continuum Computing
DESCRIPTION:Speaker: Dr. Narendra Karmarkar (Former Homi Bhabha Chair Prof.
 \, TIFR)\n\nAbstract: \nAbstract: Ultra Large-scale Linear Programming re
 fers to class of problems where number of linear inequality constraints gr
 ows exponentially w.r.t. the number of variables. "Continuum Computing" is
  a generalization of powerful interior point algorithms\, and involves com
 puting with transcendental functions\, often in several complex variables.
  \n\nThere are many potential applications of this work to several practi
 cal problems-e.g. Explainable AI\, Topology optimization for 3D printing\,
  Optimal mask design for 7nm lithography etc. However\, our focus in this 
 seminar will be on core mathematical technique and it's parallelization on
  contemporary parallel machines.\n\nWe show that the "Potential function" 
 and it's first two derivatives\, involved in the algorithm for certain cla
 ss of ultra large scale LPs\, can be computed in polynomial time in the co
 ntinuum computing paradigm\, in spite of the fact that the feasible region
  is given by exponential number of constarints. Actual numerical cross-sim
 ulation on standard computing model and machines involves approximate nume
 rical computation of inverse Laplace transform. We also apply this approac
 h to establising non-satifiability of boolean formula\, which is known to 
 require exponentially long resolution-based proofs in the standard Turing 
 machine model. It is also believed that this task can not be done efficien
 tly in quantum computing model. Earlier exposition of this work from FOCM 
 can be found in Cornell Arxive 1412.3335.pdf\, and LNCS6457.\n
URL:https://www.tcs.tifr.res.in/web/events/1043
DTSTART;TZID=Asia/Kolkata:20200121T160000
DTEND;TZID=Asia/Kolkata:20200121T170000
LOCATION:AG-66 (Lecture Theatre)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1044
DTSTAMP:20230914T125948Z
SUMMARY:Learning in Gated Neural Networks
DESCRIPTION:Speaker: Makkuva Ashok Vardhan (Department of Electrical & Comp
 uter Engineering\nUniversity of Illinois at Urbana-Champaign (UIUC)\nUnite
 d States)\n\nAbstract: \nAbstract: Gating is a key feature in modern neur
 al networks including LSTMs\, GRUs and sparsely-gated deep neural networks
 . The backbone of such gated networks is a mixture-of-experts layer\, wher
 e several experts make regression decisions and gating controls how to wei
 gh the decisions in an input-dependent manner. Despite having such a promi
 nent role in both modern and classical machine learning\, very little is u
 nderstood about parameter recovery of mixture-of-experts since gradient de
 scent and EM algorithms are known to be stuck in local optima in such mode
 ls. In this work\, we perform a careful analysis of the optimization lands
 cape and show that with appropriately designed loss functions\, gradient d
 escent can indeed learn the parameters accurately. A key idea underpinning
  our results is the design of two distinct loss functions\, one for recove
 ring the expert parameters and another for recovering the gating parameter
 s. We demonstrate the first sample complexity results for parameter recove
 ry in this model for any algorithm and demonstrate significant performance
  gains over standard loss functions in numerical experiments. \n\nBio: A
 shok is a 5th year graduate student in the ECE department at UIUC\, advise
 d by Prof. Pramod Viswanath. He obtained his Masters in ECE (advised by Pr
 of. Yihong Wu) from UIUC in 2017 and Bachelors in EE (advised by Prof. Viv
 ek Borkar) with a minor in Mathematics from IIT Bombay in 2015. His curren
 t research interests are theoretical and algorithmic aspects of machine le
 arning and information theory. He is a recipient of Best Paper Award from 
 ACM MobiHoc 2019. He has won several graduate student awards and fellowshi
 ps including Joan and Lalit Bahl Fellowship\, Sundaram Seshu International
  Student Fellowship\, and was also a finalist for the Qualcomm Innovation 
 Fellowship 2018. Outside the convex hull of research activities\, he likes
  to learn new languages\, watch and read about international films\, readi
 ng history\, and remembering trivia. For more details\, please visit: http
 ://makkuva2.web.engr.illinois.edu/\n
URL:https://www.tcs.tifr.res.in/web/events/1044
DTSTART;TZID=Asia/Kolkata:20200123T143000
DTEND;TZID=Asia/Kolkata:20200123T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1045
DTSTAMP:20230914T125948Z
SUMMARY:Paper: The Capacity of Wireless Networks
DESCRIPTION:Speaker: Kumar Saurav\n\nAbstract: \nGupta\, P.\, & Kumar\, P. 
 R. (2000). The capacity of wireless networks.\nIEEE Transactions on inform
 ation theory\, 46(2)\, 388-404.\n
URL:https://www.tcs.tifr.res.in/web/events/1045
DTSTART;TZID=Asia/Kolkata:20200124T140000
DTEND;TZID=Asia/Kolkata:20200124T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1046
DTSTAMP:20230914T125948Z
SUMMARY:Weight Distribution and List-Decoding size of Reed-Muller codes
DESCRIPTION:Speaker: Tulasi mohan Molli\n\nAbstract: \nAbstract: The proble
 m of list-decoding an error-correcting code is the following:\ngiven a rec
 eived word and a distance parameter find all codewords of the code that ar
 e within the given distance from the received word. It is a generalization
  of the more common notion of unique   decoding.\nThe weight distributio
 n of an error-correcting code counts\, for every given weight parameter\, 
 the number of codewords whose hamming weight is less than the given weight
  parameter.\nThe codewords of Reed-Muller code can be thought of as truth-
 tables of low degree polynomials. Kaufman\, Lovett\, and Porat in their wo
 rk from 2010 made a novel connection between computer science techniques u
 sed for studying low-degree polynomials and these seemingly related coding
  theory questions in the case of Reed-Muller codes.\nIn this talk\, we wil
 l see\n1) The above-mentioned result of Kaufman\, Lovett\, and Porat[KLP10
 ] and subsequent improvement of it due to Abbe\, Sphilka\, and Wigderson[A
 SW15] which give upper bounds on the weight distribution of Reed-Muller co
 des.\n2) A lower bound on the weight-distribution of Reed-Muller codes by 
 exhibiting a collection of low-degree polynomials that satisfy the weight 
 requirement for any given weight parameter. This is joint work with Bhanda
 ri\, Harsha\, and Saptarishi and independently discovered by Sberlo and Sh
 pilka[SS20].\n
URL:https://www.tcs.tifr.res.in/web/events/1046
DTSTART;TZID=Asia/Kolkata:20200124T160000
DTEND;TZID=Asia/Kolkata:20200124T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1047
DTSTAMP:20230914T125948Z
SUMMARY:Towards Optimal Secure Computation Protocols
DESCRIPTION:Speaker: Akshayaram Srinivasan (University of California\nBerke
 ley\, CA\, United States)\n\nAbstract: \nAbstract: Secure computation all
 ows a set of mutually distrusting parties to compute a joint function of t
 heir private inputs such that the parties only learn the output of the fun
 ctionality and nothing else about the inputs of the other parties. Secure 
 computation is one of the central primitives in cryptography that encompas
 ses several cryptographic abstractions and has many practical applications
 . The seminal results from the 1980s showed that every efficiently computa
 ble functionality can also be computed securely. However\, these protocols
  were prohibitively inefficient and could only be considered as feasibilit
 y results. One of the central problems in cryptography is to construct sec
 ure computation protocols that are optimal in all efficiency parameters. I
 n this talk\, I will give an overview of my recent works that make progres
 s towards constructing such optimal secure computation protocols.\nBio: Ak
 shayaram Srinivasan is a final-year Ph.D. student in the theory group at U
 C Berkeley. He received his B.Tech in Computer Science and Engineering fro
 m IIT-Madras in 2015. He is broadly interested in theoretical computer sci
 ence and in particular\, in the theory and applications of cryptography. H
 e has published research papers in top conferences in cryptography such as
  Foundations of Computer Science (FOCS)\, Crypto\, Eurocrypt\, and TCC. Hi
 s research has been recognized with the best paper award at Eurocrypt 2018
  and invitations to the Journal of Cryptology.\n
URL:https://www.tcs.tifr.res.in/web/events/1047
DTSTART;TZID=Asia/Kolkata:20200127T110000
DTEND;TZID=Asia/Kolkata:20200127T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1048
DTSTAMP:20230914T125948Z
SUMMARY:The Directed Subgraph Homeomorphism Problem
DESCRIPTION:Speaker: Vipin  S\n\nAbstract: \nThe Directed Subgraph Homeomor
 phism Problem"\, Fortune\, Hopcroft and Wyllie\, Theoretical Computer Scie
 nce\, 1980.\n
URL:https://www.tcs.tifr.res.in/web/events/1048
DTSTART;TZID=Asia/Kolkata:20200128T140000
DTEND;TZID=Asia/Kolkata:20200128T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1049
DTSTAMP:20230914T125948Z
SUMMARY:Weight distribution and List-Decoding size of Reed-Muller codes
DESCRIPTION:Speaker: Tulasi mohan Molli\n\nAbstract: \nDetails: We will fin
 ish the remainder of previous student talk. We will begin where we ended l
 ast time.\nAbstract of the previous talk: The problem of list-decoding an 
 error-correcting code is the following:\ngiven a received word and a dista
 nce parameter find all codewords of the code that are within the given di
 stance from the received word. It is a generalization of the more common 
 notion of unique decoding.\nThe weight distribution of an error-correcting
  code counts\, for every given weight parameter\, the number of codewords
  whose hamming weight is less than the given weight parameter.\nThe codew
 ords of Reed-Muller code can be thought of as truth-tables of low degree 
 polynomials. Kaufman\, Lovett\, and Porat in their work from 2010 made a 
 novel connection between computer science techniques used for studying lo
 w-degree polynomials and these seemingly related coding theory questions 
 in the case of Reed-Muller codes.\nIn this talk\, we will see\n1) The abov
 e-mentioned result of Kaufman\, Lovett\, and Porat[KLP10] and subsequent 
 improvement of it due to Abbe\, Sphilka\, and Wigderson[ASW15] which give
  upper bounds on the weight distribution of Reed-Muller codes.\n2) A lower
  bound on the weight-distribution of Reed-Muller codes by exhibiting a co
 llection of low-degree polynomials that satisfy the weight requirement fo
 r any given weight parameter. This is joint work with Bhandari\, Harsha\,
  and Saptarishi and independently discovered by Sberlo and Shpilka[SS20].
 \n
URL:https://www.tcs.tifr.res.in/web/events/1049
DTSTART;TZID=Asia/Kolkata:20200131T140000
DTEND;TZID=Asia/Kolkata:20200131T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1050
DTSTAMP:20230914T125948Z
SUMMARY:Quantum versus Randomized Communication Complexity\, with Efficient
  Players
DESCRIPTION:Speaker: Uma Girish (Princeton University\nUnited States)\n\nAb
 stract: \nAbstract:  We study a new type of separation between quantum a
 nd classical communication complexity\, a separation which is obtained usi
 ng quantum protocols where all parties are efficient\, in the sense that t
 hey can be implemented by small quantum circuits with oracle access to the
 ir inputs. More precisely\, we give an explicit partial Boolean function t
 hat can be computed in the quantum-simultaneous-with-entanglement model of
  communication\, however\, every interactive randomized protocol is of exp
 onentially larger cost. Furthermore\, all the parties in the quantum proto
 col can be implemented by quantum circuits of small size with blackbox acc
 ess to the inputs. Our result qualitatively matches the strongest known se
 paration between quantum and classical communication complexity and is obt
 ained using a quantum protocol where all parties are efficient. Our proof 
 technique is new in the context of communication complexity and is based o
 n techniques from the recent oracle separation of BQP and PH.\nThis is a j
 oint work with Ran Raz and Avishay Tal.\n
URL:https://www.tcs.tifr.res.in/web/events/1050
DTSTART;TZID=Asia/Kolkata:20200207T113000
DTEND;TZID=Asia/Kolkata:20200207T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1051
DTSTAMP:20230914T125948Z
SUMMARY:Artificial Intelligence using Emerging Eevices and Architectures
DESCRIPTION:Speaker: Dr. Debanjan Bhowmik (Assistant Professor\nDepartment 
 of Electrical Engineering\nIndian Institute of Technology Delhi)\n\nAbstra
 ct: \nAbstract: Artificial Intelligence (AI)/ Machine Learning (ML)/ Neur
 al Network (NN) algorithms are being widely used currently for various app
 lications that include self driving cars\, virtual assistants on smartphon
 es and other devices\, etc. However\, the memory-computing separation in e
 xisting computer hardware makes implementation of these algorithms on the 
 hardware inefficient in terms of power and speed. As a result\, new device
 s and architectures are being proposed to run these algorithms more effici
 ently.\nIn this context\, I will discussed the latest work carried out in 
 our research group on the implementation of AI/ML/NN algorithms in a cross
 bar based in-memory computing architecture\, as well as a quantum architec
 ture. For the former\, we have used both spin based devices (spin orbit to
 rque driven domain wall devices) [1\,2\,3] and charge based devices (a sin
 gle conventional silicon transistor synapse) [4]. We have used both non-sp
 iking NN algorithms\, used abundantly in the ML community\, [2\,4] as well
  as spiking NN algorithms\, inspired from the working of the brain [3]. Fo
 r the latter\, we have proposed a novel quantum algorithm\, implemented it
  on the "qiskit" simulation framework and shown very high classification a
 ccuracy on different popular ML datasets [5].\nReferences:\n1. Debanjan Bh
 owmik et al. "Deterministic domain wall motion orthogonal to current flow 
 due to spin orbit torque". Scientific Reports \, Vol. 5\, 11823 (2015)\n2.
  Debanjan Bhowmik et al. "On-chip learning for domain wall synapse based F
 ully Connected Neural Network". Journal of Magnetism and Magnetic Material
 s Vol. 489\, 165434 (2019)\n3. Upasana Sahu\, Aadit Pandey\, Kushaagra Goy
 al and Debanjan Bhowmik. "Spike time dependent plasticity (STDP) enabled l
 earning in spiking neural networks using domain wall based synapses and ne
 urons". AIP Advances Vol. 9\, 12 (2019)\n4. Nilabjo Dey\, Janak Sharda\, U
 tkarsh Saxena\, Divya Kaushik\, Utkarsh Singh\, Debanjan Bhowmik. "On-Chip
  Learning in a Conventional Silicon MOSFET Based Analog Hardware Neural Ne
 twork". IEEE Biomedical Circuits and Systems Conference (BioCAS)\, Nara\, 
 Japan (2019)\n5. S. Adhikary\, S. Dangwal and D. Bhowmik\, Supervised lear
 ning with a quantum classifier using multi-level systems\, Quantum Informa
 tion Processing 19\, 89 (2020).\nBio: Dr. Debanjan Bhowmik is currently a
 n Assistant Professor in the Department of Electrical Engineering\, Indian
  Institute of Technology Delhi. He obtained his BTech degree in Electrical
  Engineering from Indian Institute of Technology Kharagpur in 2010. He obt
 ained his PhD degree from University of California Berkeley in 2015\, work
 ing in the field of nano magnetism and spintronics. Currently at IIT Delhi
  he works on Artificial Intelligence using emerging devices like spintroni
 c devices and emerging architectures like in-memory computing architecture
  and quantum architecture.\n
URL:https://www.tcs.tifr.res.in/web/events/1051
DTSTART;TZID=Asia/Kolkata:20200211T140000
DTEND;TZID=Asia/Kolkata:20200211T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1052
DTSTAMP:20230914T125948Z
SUMMARY:Characterization of Reed Muller Codes
DESCRIPTION:Speaker: Arghya Chakraborty\n\nAbstract: \nAbstract : In this t
 alk\, I shall discuss about linear codes-specifically Reed Solomon\, Reed 
 Muller codes and their duals. Reed Muller codes are a generalization of Re
 ed Solomon codes but here we will also see that Reed Muller is a subcode o
 f Reed Solomon codes.\n
URL:https://www.tcs.tifr.res.in/web/events/1052
DTSTART;TZID=Asia/Kolkata:20200212T160000
DTEND;TZID=Asia/Kolkata:20200212T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1053
DTSTAMP:20230914T125948Z
SUMMARY:The Propp-Wilson Perfect Sampling Algorithm
DESCRIPTION:Speaker: Sayantan Chakraborty (TIFR\, Mumbai)\n\nAbstract: \nAb
 stract:*The problem of approximate sampling using Markov Chain Monte Carlo
  has received considerable attention in the Theoretical Computer Science a
 nd Physics communities. In this approach one typically takes a Markov Chai
 n $M$ with a stationary distribution $\\Pi$ over a set $\\mathcal{S }$ and
  runs it for a pre-specified amount of time $T$ from a fixed starting stat
 e $s_0$. Using various techniques such as Coupling\, Spectral Gap\, etc.\,
  the distribution of the output of the chain after $T$ steps\, say\, $s_T$
 \,  is shown to be close to the stationary distribution $\\Pi$ in total v
 ariation distance . $T$ typically has a dependence on $\\log(1/\\eps)$ whe
 re $\\eps$ is the desired upper bound on the TV distance between the distr
 ibution of $s_T$ and $\\Pi$.* *However\, in this talk we will be intereste
 d in producing a sample from $\\mathcal{S}$ that is distributed exactly ac
 cording to $\\Pi$\, i.e\, we require $\\eps=0$. Notice\, that the above ap
 proximate sampling approach cannot be used directly as we would require $T
 $ to be $\\infty$ as it depends on $\\log(1/\\eps)$. To overcome the above
  issues Propp and Wilson [1996] came up with a beautiful algorithm known a
 s Coupling From The Past (CFTP). In this talk we will arrive at the algori
 thm by taking various erroneous approaches and correcting them.*\n
URL:https://www.tcs.tifr.res.in/web/events/1053
DTSTART;TZID=Asia/Kolkata:20200214T140000
DTEND;TZID=Asia/Kolkata:20200214T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1054
DTSTAMP:20230914T125948Z
SUMMARY:Unique Games with Value Half and its Applications.
DESCRIPTION:Speaker: Amey Bhangale (University of California\, Riverside\nC
 alifornia\, U.S.)\n\nAbstract: \nAbstract: PCP Theorem characterizes the c
 lass NP and gives hardness of approximation for many optimization problems
 . Despite this\, several tight hardness of approximation results remain el
 usive via the PCP theorem. In 2002\, Khot proposed the Unique Games Conjec
 ture. Since the formulation of the conjecture\, it has found interesting c
 onnections to the tight hardness of approximation results for many optimiz
 ation problems. \n\nIn this talk\, I will discuss recent developments abou
 t the Unique Games Conjecture. The 2-to-2 Games Theorem implies that it is
  NP-hard to distinguish between Unique Games instances with assignment sat
 isfying at least 1/2 fraction of the constraints vs. no assignment satisfy
 ing more than \\eps fraction of the constraints\, for every constant \\eps
 >0. We show that the reduction can be transformed in a non-trivial way to 
 give a stronger guarantee on the Unique Games instance and use this guaran
 tee to convert the known Unique Games-hardness results to NP-hardness for 
 several optimization problems. \n\nBased on joint work with SubhashK Khot.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1054
DTSTART;TZID=Asia/Kolkata:20200218T141500
DTEND;TZID=Asia/Kolkata:20200218T151500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1055
DTSTAMP:20230914T125948Z
SUMMARY:The Skolem - Mahler - Lech Theorem
DESCRIPTION:Speaker: Prabhat Kumar Jha\n\nAbstract: \nAbstract: The Skolem 
 - Mahler - Lech Theorem states that given any linear recurrence sequence o
 ver any field of characteristic 0\, the set of positions where 0 occurs is
  union of a finite set and finitely many arithmetic progressions. We will 
 discuss a proof of this theorem.\n
URL:https://www.tcs.tifr.res.in/web/events/1055
DTSTART;TZID=Asia/Kolkata:20200221T140000
DTEND;TZID=Asia/Kolkata:20200221T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1056
DTSTAMP:20230914T125948Z
SUMMARY:Optimal Resource Allocation and Scheduling in Networks and Systems
DESCRIPTION:Speaker: Rahul Singh (The Ohio State University\nColumbus\, Ohi
 o\, United States.)\n\nAbstract: \nAbstract: I will provide an account of 
 my research in various areas. As an exemplar\, I will discuss the first tw
 o topics in greater detail.\n1) Decentralized Control of Stochastic Dynami
 cal Systems: We begin by developing new methods to design decentralized c
 ontrol laws for stochastic dynamical systems which perform as well as an o
 ptimal centralized policy. We illustrate these methods on real-time multi
 -hop communication networks. The problem is challenging because it involv
 es inducing coordination amongst the controllers without knowing all the s
 tates of individual agents.\n\n2) Reinforcement Learning: We consider the 
 problem of designing learning rules for Markov decision processes under c
 onstraints on the cost expenditures by the controller/agent.\n\n3) Asympto
 tic Smoothness of a Service Discipline: We introduce a new performance met
 ric that is useful in order to characterize schedulers for networks servi
 ng real-time traffic. We also show that the popular MaxWeight scheduler p
 erforms well with respect to it.\n\n4) Networked Control Systems: We addre
 ss the problem of how to optimally schedule data packets over an unreliabl
 e channel in order to minimize the estimation error of a remote linear es
 timator that tracks the state of a Gauss Markov process. We show that a s
 imple index rule that calculates the value of information (VoI) of each pa
 cket\, and then schedules the packet with the largest current value of Vo
 I\, is optimal.\n\nI will conclude the talk by discussing my immediate and
  long-term research directions.\n\nBio: Rahul Singh is a postdoctoral res
 earcher at the Ohio State University. He received the B.Tech. degree in El
 ectrical Engineering from Indian Institute of Technology Kanpur in 2009\,
  the M.S. degree in Electrical Engineering from the University of Notre D
 ame in 2011\, and the Ph.D. degree in Computer Engineering from the Depart
 ment of  Electrical and Computer Engineering\, Texas A&M University\, Co
 llege Station\, in 2015. He was Postdoctoral Researcher at the Laboratory
  for Information and Decision Systems (LIDS)\, Massachusetts Institute of 
 Technology. He also worked as a Data Scientist at Encored Inc.\, and was 
 part of the Machine Learning Group at Intel. His research interests inclu
 de decentralized control of large-scale complex cyber-physical systems\, o
 peration of electricity markets with renewable energy\, optimal schedulin
 g and control of networks serving real time traffic\, machine learning\, 
 game theory\, stochastic control\, multi-armed bandits and reinforcement l
 earning.\n
URL:https://www.tcs.tifr.res.in/web/events/1056
DTSTART;TZID=Asia/Kolkata:20200224T110000
DTEND;TZID=Asia/Kolkata:20200224T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1057
DTSTAMP:20230914T125948Z
SUMMARY:STCS Annual Symposium
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1057
DTSTART;TZID=Asia/Kolkata:20200228T093000
DTEND;TZID=Asia/Kolkata:20200301T163000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1058
DTSTAMP:20230914T125948Z
SUMMARY:Integer Linear Programs and Local Search for Max-Cut (Author: Svato
 pluk Poljak)
DESCRIPTION:Speaker: Vidya Sagar Sharma\n\nAbstract: \nAbstract: Schaffer 
 and Yannakakis have shown that the max-cut problem with the FLIP neighborh
 ood is polynomial-time local search (PLS) complete\, and hence among the m
 ost difficult problems in the PLS class. The FLIP neighbourhood of a 2-par
 tition is defined by moving a single vertex to the opposite class. In this
  paper\, the author has shown that when restricted to the cubic graph\, th
 e FLIP local search becomes "easy" and finds a local max-cut in $O(n^2)$ s
 teps.\nPaper Link: https://epubs.siam.org/doi/pdf/10.1137/S009753979324535
 0\n
URL:https://www.tcs.tifr.res.in/web/events/1058
DTSTART;TZID=Asia/Kolkata:20200306T140000
DTEND;TZID=Asia/Kolkata:20200306T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1059
DTSTAMP:20230921T105045Z
SUMMARY:Distribution oblivious risk-aware bandit algorithms
DESCRIPTION:Speaker: Jayakrishnan Nair (Indian Institute of Technology Bomb
 ay)\n\nAbstract: \nClassical multi-armed bandit algorithms are tuned to wo
 rk well for a pre-specified class of reward distributions\, defined via th
 eir support\, or moment/tail bounds. In this work\, we consider the proble
 m of oblivious best arm identification\, i.e.\, where the algorithm has no
  prior information about the class of reward distributions. We establish f
 undamental limits on the performance of oblivious algorithms\, and further
  propose algorithms that asymptotically meet these limits. Additionally\, 
 we allow for risk-aware arm selection\, where we balance the expected rewa
 rd associated with an arm with the corresponding risk.\nThis talk is based
  on joint work with Anmol Kagrecha\, Ashutosh Kumar\, and Krishna Jagannat
 han.\n
URL:https://www.tcs.tifr.res.in/web/events/1059
DTSTART;TZID=Asia/Kolkata:20200505T160000
DTEND;TZID=Asia/Kolkata:20200505T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1060
DTSTAMP:20230921T105045Z
SUMMARY:Battle of Bandits: Online Learning from Relative Preferences
DESCRIPTION:Speaker: Aditya Gopalan (Indian Institute of Science\, Bangalor
 e)\n\nAbstract: \nWe consider the problem of sequentially learning good al
 ternatives from among a pool\, but with only relative utility feedback fro
 m adaptively chosen subsets. At each round\, the learner chooses a subset 
 of alternatives and can observe which ones are preferred over the others i
 n the subset. This type of feedback is natural in several domains\, especi
 ally where human preferences are elicited in a repeated fashion ("Which of
  A\, B\, C\, D do you prefer?")\, e.g.\, the design of surveys and expert 
 reviews\, web search and recommender systems\, and other settings like ran
 king in multiplayer games. Tranditional approaches such as the multi-armed
  bandit model only absolute utility feedback\, and are thus inadequate to 
 express relative choices. The dueling bandit (Yue-Joachims'09) is a more r
 ecent attempt to model online learning with pairwise preferences\, but the
  more general\, realistic\, and combinatorially harder case of working wit
 h preferences expressed over subsets has largely been unexplored. We take 
 a step in this direction and formulate what we call the battling bandit pr
 oblem\, where one seeks to learn an optimal item or ranking of n items by 
 sequentially choosing up to size-k subsets at each round and exploiting re
 lative preferences arising from a choice model such as the well-known Plac
 kett-Luce probability model. We study variants of learning objectives from
  subsetwise feedback: Identifying the best item\, the set of top-k items\,
  full ranking etc.\, in both the probably approximately correct (PAC) or r
 egret optimization setting\, and design algorithms with optimality propert
 ies. This is joint work with Aadirupa Saha (Indian Institute of Science).\
 nBio:\nAditya Gopalan is an Assistant Professor and INSPIRE Faculty Fellow
  at the Indian Institute of Science\, Dept. of Electrical Communication En
 gineering. He received the Ph.D. degree in electrical engineering from The
  University of Texas at Austin\, and the B.Tech. and M.Tech. degrees in el
 ectrical engineering from the Indian Institute of Technology Madras. He wa
 s an Andrew and Erna Viterbi Post-Doctoral Fellow at the Technion-Israel I
 nstitute of Technology. His research interests include machine learning an
 d statistical inference\, control\, and resource allocation algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1060
DTSTART;TZID=Asia/Kolkata:20200512T140000
DTEND;TZID=Asia/Kolkata:20200512T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1061
DTSTAMP:20230914T125949Z
SUMMARY:Tapestry: A Single-Round Smart Pooling Technique for COVID-19 Testi
 ng
DESCRIPTION:Speaker: Manoj Gopalkrishnan (Department of Electrical Engineer
 ing\nIndian Institute of Technology Bombay\nMumbai)\n\nAbstract: \nAbstrac
 t: The COVID-19 pandemic has strained testing capabilities worldwide. Ther
 e is an urgent need to find economical and scalable ways to test more peop
 le. We present Tapestry\, a novel quantitative nonadaptive pooling scheme 
 to test many samples using only a few tests. The underlying molecular diag
 nostic test is any real-time RT-PCR diagnostic panel approved for the dete
 ction of the SARS-CoV-2 virus. In cases where most samples are negative fo
 r the virus\, Tapestry accurately identifies the status of each individual
  sample with a single round of testing in fewer tests than simple two-roun
 d pooling. We also present a companion Android application BYOM Smart Test
 ing which guides users through the pipetting steps required to perform the
  combinatorial pooling. The results of the pooled tests can be fed into th
 e application to recover the status and estimated viral load for each indi
 vidual sample.\n
URL:https://www.tcs.tifr.res.in/web/events/1061
DTSTART;TZID=Asia/Kolkata:20200526T140000
DTEND;TZID=Asia/Kolkata:20200526T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1062
DTSTAMP:20230921T105045Z
SUMMARY:Symmetry in Syndrome Decoding of Reed-Muller Codes
DESCRIPTION:Speaker: Andrew Thangaraj (IIT Madras)\n\nAbstract: \nReed--Mul
 ler (RM) codes\, a classical family of codes known for their elegant algeb
 raic structure\, have recently been shown to achieve capacity under maximu
 m-likelihood (ML) decoding on the binary erasure channel and this has reki
 ndled interest in their efficient decoding. We consider the code family RM
 (m-3\,m) and develop a new ML decoder\, for transmission over the binary s
 ymmetric channel\, that exploits their large symmetry group. The new decod
 er has complexity O(m^3)\, which is lower than an earlier method introduce
 d by Seroussi and Lempel in 1983.\nBio: Andrew Thangaraj received his B.Te
 ch in Electrical Engineering from the Indian Institute of Technology (IIT)
 \, Madras\, India in 1998 and a PhD in Electrical Engineering from the Geo
 rgia Institute of Technology\, Atlanta\, USA in 2003. He was a post-doctor
 al researcher at the GTL-CNRS Telecom lab at Georgia Tech Lorraine\, Metz\
 , France from August 2003 to May 2004. From June 2004\, he has been with t
 he Department of Electrical Engineering\, IIT Madras\, where he is current
 ly a professor. From Jan 2012 to Jan 2018\, he served as Editor for the IE
 EE Transactions on Communications.\nSince July 2018\, he has been serving 
 as an Associate Editor for Coding Techniques for the IEEE Transactions on 
 Information Theory. Since Oct 2011\, he has been serving as NPTEL coordina
 tor at IIT Madras. He has played a key role in initiating and running NPTE
 L online courses and certification. He is currently a National MOOCs Coord
 inator for NPTEL in the SWAYAM project of the MHRD.\n
URL:https://www.tcs.tifr.res.in/web/events/1062
DTSTART;TZID=Asia/Kolkata:20200602T140000
DTEND;TZID=Asia/Kolkata:20200602T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1063
DTSTAMP:20230914T125949Z
SUMMARY:Weighted min-cut: Sequential\, Cut-query and Streaming algorithms
DESCRIPTION:Speaker: Dr. Sagnik Mukhopadhyay (KTH\, Stockholm)\n\nAbstract:
  \nAbstract: Consider the following 2-respecting min-cut problem: Given a 
 weighted graph G and its spanning tree T\, find the minimum cut among the 
 cuts that contain at most two edges in T. This problem is an important sub
 routine in Karger's celebrated randomized near-linear-time min-cut algorit
 hm [STOC'96]. I will present a new approach to this problem which can be e
 asily implemented in many settings\, leading to the following randomized m
 in-cut algorithms for weighted graphs.\n- An O(m log^2 n)-time sequential 
 algorithm: This improves Karger's long-standing O(m log^3 n) bound. Improv
 ements over Karger's bounds were previously known only under a rather stro
 ng assumption that the input graph is simple (unweighted without parallel 
 edges) [Henzinger\, Rao\, Wang\, SODA'17\; Ghaffari\, Nowicki\, Thorup\, S
 ODA'20]. For unweighted graphs (possibly with parallel edges) and using bi
 t operations\, our bound can be further improved.\n- An algorithm that req
 uires \\tilde O(n) cut queries to compute the min-cut of a weighted graph:
  This answers an open problem by Rubinstein\, Schramm\, and Weinberg [ITCS
 '18]\, who obtained a similar bound for simple graphs. Our bound is tight 
 up to polylogarithmic factors.\n- A dynamic streaming algorithm that requi
 res \\tilde O(n) space and O(log n) passes to compute the min-cut: The onl
 y previous non-trivial exact min-cut algorithm in this setting is the 2-pa
 ss \\tilde O(n)-space algorithm on simple graphs [Rubinstein et al.\, ITCS
 '18] (observed by Assadi\, Chen\, and Khanna [STOC'19]).\nIn contrast to K
 arger's 2-respecting min-cut algorithm which deploys sophisticated dynamic
  programming techniques\, our approach exploits some cute structural prope
 rties so that it only needs to compute the values of \\tilde O(n) cuts cor
 responding to removing \\tilde O(n) pairs of tree edges\, an operation tha
 t can be done quickly in many settings.\nThis is joint work with Danupon N
 anongkai.\n
URL:https://www.tcs.tifr.res.in/web/events/1063
DTSTART;TZID=Asia/Kolkata:20200609T140000
DTEND;TZID=Asia/Kolkata:20200609T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1064
DTSTAMP:20230914T125949Z
SUMMARY:Optimal Design of Queuing Systems via Compositional Stochastic Prog
 ramming
DESCRIPTION:Speaker: Ketan Rajawat (Department of Electrical Engineering\,\
 nIndian Institute of Technology\, Kanpur)\n\nAbstract: \nAbstract: Well-de
 signed queuing systems form the backbone of modern communications\, distri
 buted computing\, and content delivery architectures. Designs balancing in
 frastructure costs and user experience indices require tools from tele-tra
 ffic theory and operations research. A standard approach to designing such
  systems involves formulating optimization problems that strive to maximiz
 e the pertinent utility functions while adhering to quality-of-service and
  other physical constraints. In many cases\, formulating such problems nec
 essitates making simplistic assumptions on arrival and departure processes
  to keep the problem tractable.\n\nThis talks will introduce a stochastic 
 optimization framework for designing queuing systems where the exogenous p
 rocesses may have arbitrary and unknown distributions. We show that many s
 uch queuing design problems can generally be formulated as stochastic opti
 mization problems where the objective and constraints are non-linear funct
 ions of expectations. The compositional structure obviates the use of clas
 sical stochastic approximation approaches where the stochastic gradients a
 re often required to be unbiased. To this end\, a constrained stochastic c
 ompositional gradient descent algorithm is proposed that utilizes a tracki
 ng step for the expected value functions. The non-asymptotic performance o
 f the proposed algorithm is characterized by its iteration complexity. Fur
 ther improvements are proposed that build upon the primal-dual saddle poin
 t algorithm to result in zero constraint violation and O(T-0.25) optimalit
 y gap. Numerical tests allow us to validate the theoretical results and de
 monstrate the efficacy of the proposed algorithm.\n\nBio: Ketan Rajawat (S
 '06–M'12) received his B.Tech and M.Tech degrees in Electrical Engineeri
 ng from the Indian Institute of Technology (IIT) Kanpur\, India\, in 2007\
 , and his Ph.D. degree in Electrical and Computer Engineering from the Uni
 versity of Minnesota\, Minneapolis\, MN\, USA\, in 2012. He is currently a
 n Associate Professor in the Department of Electrical Engineering\, IIT Ka
 npur. His research interests are in the broad areas of signal processing\,
  robotics\, and communications networks\, with particular emphasis on dist
 ributed optimization and online learning. His current research focuses on 
 the development and analysis of distributed and asynchronous optimization 
 algorithms\, online convex optimization algorithms\, stochastic optimizati
 on algorithms\, and the application of these algorithms to problems in mac
 hine learning\, communications\, and smart grid systems. He is currently s
 erving as an Associate Editor with the IEEE Communications Letters and IEE
 E Transactions on Signal Processing. He is also the recipient of the 2018 
 INSA Medal for Young Scientists and the 2019 INAE Young Engineer Award.\n
URL:https://www.tcs.tifr.res.in/web/events/1064
DTSTART;TZID=Asia/Kolkata:20200616T140000
DTEND;TZID=Asia/Kolkata:20200616T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1065
DTSTAMP:20230914T125949Z
SUMMARY:Half-integral Duals\, Connectivity Augmentation and Multiflows in P
 lanar Graphs
DESCRIPTION:Speaker: Naveen Garg (Computer Science and Engineering\nIndian 
 Institute of Technology Delhi\nNew Delhi)\n\nAbstract: \nAbstract: Given a
 n edge weighted graph and a spanning tree\, $T$\, the {\\em tree augmentat
 ion problem} is to pick a minimum weight set of edges\, $F$\, such that $T
 \\cup F$ is 2-edge connected. Williamson et.al. gave a 2-approximation alg
 orithm for this problem using the primal-dual schema. We show that when ed
 ge weights are integral\, the WGMV procedure can be modified to obtain a h
 alf-integral dual.\n\nThe tree augmentation problem has an interesting con
 nection to routing flow in graphs where the union of supply and demand is 
 planar. The half-integrality of the dual leads to a tight 2-approximate ma
 x-half-integral-flow min-multicut theorem and a 4-approximate max-integral
  flow min-multicut theorem.\n(joint work with Nikhil Kumar and Andras Sebo
 )\n
URL:https://www.tcs.tifr.res.in/web/events/1065
DTSTART;TZID=Asia/Kolkata:20200623T140000
DTEND;TZID=Asia/Kolkata:20200623T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1066
DTSTAMP:20230914T125949Z
SUMMARY:Proof Complexity of MaxSAT Resolution
DESCRIPTION:Speaker: Gaurav Sood (Institute of Mathematical Sciences\nChenn
 ai\, Tamil Nadu)\n\nAbstract: \nZoom details:\nMeeting ID: 613 566 8340\nP
 assword: 183102\nAbstract: Boolean satisfiability (SAT) is the quintessent
 ial NP-complete problem. It has given rise to many areas of research wit
 hin theoretical computer science\, one of them being proof complexity. Gi
 ven a proof system for SAT\, we ask questions of the following form: is th
 ere a short proof that an unsatisfiable formula is unsatisfiable?\n\nMaxSA
 T is the related problem of determining the maximum number of satisfiable
  clauses\, and like SAT\, it has its own proof systems. In this talk\, we 
 will study a proof system for MaxSAT proposed by Bonet et al. in 2007\, an
 d compare it with proof systems for SAT. This is joint work with Yuval Fil
 mus\, Meena Mahajan and Marc Vinyals.\n
URL:https://www.tcs.tifr.res.in/web/events/1066
DTSTART;TZID=Asia/Kolkata:20200625T143000
DTEND;TZID=Asia/Kolkata:20200625T153000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1067
DTSTAMP:20230914T125949Z
SUMMARY:Theory of Field $\\mathbb{C} $ is Decidable
DESCRIPTION:Speaker: Prabhat Kumar Jha\n\nAbstract: \nZoom Details:\nLink: 
 https://zoom.us/j/98172222418?pwd=b0htSDQ5NDRKQ050K0d6cHJ3YnZXQT09\nMeetin
 g ID: 981 7222 2418\nPassword: studsem\nAbstract:  Many optimization pro
 blems reduce to finding truth value of quantified formulas over real or/an
 d complex numbers. In this talk we will cover a proof of decidability of t
 heories of real numbers and complex numbers due to Tarski. We will begin b
 y providing an algorithm to locate roots of multi-variable polynomials ove
 r these fields and then use quantifier elimination techniques to prove dec
 idability. If time permits\, we will discuss its applications to optimizat
 ion and verification problems.\nNote: There is no prerequisite from Mathem
 atical Logic or Computability theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1067
DTSTART;TZID=Asia/Kolkata:20200704T160000
DTEND;TZID=Asia/Kolkata:20200704T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1068
DTSTAMP:20230914T125949Z
SUMMARY:On Decision Tree Complexity of Boolean Functions
DESCRIPTION:Speaker: Swagato Sanyal (Indian Institute of Technology Kharagp
 ur\nKharagpur\, West Bengal)\n\nAbstract: \nTalk will be held on Zoom.\nAb
 stract: The decision tree model\, also known as the query model\, is a sim
 ple model of computation. Besides having an intuitive appeal\, and offerin
 g a natural paradigm for algorithm design\, it is often possible to theore
 tically nail down the exact complexity of many interesting algorithmic tas
 ks using currently available methods\, completely and unconditionally\; fo
 r more complex models of computation such an aspiration is currently a dis
 tant dream. In this talk we will first introduce and motivate query model\
 , and then present a recent work of ours on the query complexity of an imp
 ortant subclass of problems\, called composed functions. The latter part i
 s based on joint work with Dmitry Gavinsky\, Troy Lee and Miklos Santha wh
 ich has appeared in ICALP 2019.\n
URL:https://www.tcs.tifr.res.in/web/events/1068
DTSTART;TZID=Asia/Kolkata:20200707T140000
DTEND;TZID=Asia/Kolkata:20200707T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1069
DTSTAMP:20230914T125949Z
SUMMARY:On Realizable Distributions
DESCRIPTION:Speaker: Siddharth Bhandari\n\nAbstract: \nJoin Zoom Meeting\nh
 ttps://zoom.us/j/98172222418?pwd=b0htSDQ5NDRKQ050K0d6cHJ3YnZXQT09\nMeeting
  ID: 981 7222 2418\nPassword: studsem\nAbstract: Coupling arguments are co
 mmonplace in approximate and perfect sampling. A coupling is a joint distr
 ibution between RVs: it helps us relate and compare distributions of the R
 Vs.\n\nWe will study the following:\nGiven RVs X_1\, X_2\, X_3\, X_4\,....
 \, X_n each taking a value in $\\Omega$ and marginally distributed accordi
 ng to $\\mu_1\, \\mu_2\, ...\, \\mu_n$ on $\\Omega^n$\, we say a RV $Y$ di
 stributed according to $\\tau$ is realizable wrt to $X_1\,...\, X_n$ iff f
 or all joint distributions $\\mu$ of $X_1\,..\, X_n$ such that each $X_i~\
 \mu_i$ there exists a joint distribution  $\\mu'$ of $X_1\,...\, X_n\, Y$
  such that 1> $(X_1\, X_2\, ...\, X_n)~\\mu$  and $Y~\\tau$ 2> Pr_{\\mu
 '}[Y\\in {X_1\,...\, X_n}]=1.\nWe will show that  a distribution $\\tau$ 
 is realizable wrt to $\\mu_1\,..\, \\mu_n$ iff for all $S\\subseteq \\Omeg
 a$ we have: $\\mu_i(S)\\leq \\tau(S)\\leq \\mu_j (S)$ for some $i\,j\\in [
 n]$.\n
URL:https://www.tcs.tifr.res.in/web/events/1069
DTSTART;TZID=Asia/Kolkata:20200711T160000
DTEND;TZID=Asia/Kolkata:20200711T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1070
DTSTAMP:20230914T125949Z
SUMMARY:Approximating the Nash Social Welfare with Subadditive Valuations
DESCRIPTION:Speaker: Umang Bhaskar\n\nAbstract: \nAbstract:  How should o
 ne divide $m$ goods between $n$ agents\, given the utility each agent has 
 when allocated a subset of goods? Allocations which maximize the Nash Soci
 al Welfare --- the product of agent utilities for their allocation --- are
  known to possess a number of natural and agreeable properties. Unfortunat
 ely\, maximizing the Nash Social Welfare is known to be APX-hard\, even wh
 en agent utility functions are additive over the set of goods.\nWe present
  an algorithm that for the general case of subadditive utility functions f
 or the agents\, obtains an $O(n)$-approximation to the optimal Nash Social
  Welfare\, given value oracle access to the utility functions. This improv
 es upon a previous $O(n log n)$ algorithm for submodular utilities (SODA '
 20). Our approximation ratio is tight for subadditive utilities and for va
 lue oracle access.\nThis is joint work with Siddharth Barman\, Anand Krish
 na\, and Ranjani Sundaram.\n
URL:https://www.tcs.tifr.res.in/web/events/1070
DTSTART;TZID=Asia/Kolkata:20200717T140000
DTEND;TZID=Asia/Kolkata:20200717T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1071
DTSTAMP:20230914T125949Z
SUMMARY:The class of poly-sized Algebraic Branching Programs is closed unde
 r Factoring
DESCRIPTION:Speaker: Prerona  Chatterjee\n\nAbstract: \nTalk will be held i
 n Zoom.\nAbstract:  In the 1980s\, Kaltofen proved one of the most remar
 kable results in algebraic complexity theory. He showed that if a polynomi
 al can be computed by a "small" circuit\, then each of its factors can als
 o be computed by "small" circuits. In fact\, given a circuit for the origi
 nal polynomial\, he also gave an efficient algorithm for computing circuit
 s for the factors. This result has many applications\, one of which is the
  algebraic analogue of the "hardness vs randomness" question.\n\nHowever\,
  his proof did not extend to more restricted models of computation. Recent
 ly Amit Sinhababu and Thomas Thierauf showed a similar statement for the c
 lass of Algebraic Branching Programs (or ABPs). Formally\, they proved the
  following statement. If an n variate degree d polynomial f can be compute
 d by an ABP of size s\, then each of its factors can be computed by an ABP
  of size at most poly(s\, n\, d).\nIn this talk\, we will go over the proo
 f techniques used in the previous results of this kind\, and see an overvi
 ew of the modifications Sinhababu and Theirauf made to these techniques to
  get their result.\n\nNo background of the field will be assumed.\n
URL:https://www.tcs.tifr.res.in/web/events/1071
DTSTART;TZID=Asia/Kolkata:20200718T160000
DTEND;TZID=Asia/Kolkata:20200718T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1072
DTSTAMP:20230914T125949Z
SUMMARY:A Largish Sum-of-squares Implies Circuit Hardness (and Derandomizat
 ion)
DESCRIPTION:Speaker: Prof. Nitin Saxena (Indian Institute of Technology Kan
 pur\nKanpur\, Uttar Pradesh)\n\nAbstract: \nAbstract: We study the sum of
  squares (*SOS*) representation of polynomials\, i.e. f = \\sum_{i\\in s} 
 c_i f_i^2 \, where c_i are field elements and f_i(x_1\,\\ldots\,x_n) are p
 olynomials. We are interested in `measuring' the number of monomials that 
 appear across f_i's\; call this *support-sum* S(f). Let the degree of f be
  d and\, for simplicity of exposition\, fix n=1. We conjecture: For some *
 explicit* f and some constant \\epsilon > 1/2\, S(f) \\ge d^\\epsilon. We 
 prove that the conjecture implies VP\\ne VNP (& blackbox-PIT in QuasiP). A
  more sophisticated version of the conjecture\, for sum-of-cubes represent
 ation\, implies blackbox-PIT is in P.\n\nNote that S(f) \\ge d^{1/2} is tr
 ivially achieved. So\, compared to this\, a marginally better lower bound 
 in the SOS suffices to solve the major questions of algebraic complexity. 
 The *SOS-conjecture* is largely field independent\, and is itself supporte
 d by a dimension-based fact: It holds for a `randomly chosen' degree-d pol
 ynomial f(x).\nThis is ongoing work with Pranjal Dutta (CMI/IITK) and Thom
 as Thierauf (Ulm/Aalen).\n
URL:https://www.tcs.tifr.res.in/web/events/1072
DTSTART;TZID=Asia/Kolkata:20200723T140000
DTEND;TZID=Asia/Kolkata:20200723T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1073
DTSTAMP:20230914T125949Z
SUMMARY:Simple\, Credible\, and Approximately-Optimal Auctions
DESCRIPTION:Speaker: Santhoshini Velusamy (Harvard University\nCambridge\, 
 Massachusetts.)\n\nAbstract: \nAbstract:  We present a general framework
 \, applicable to both truthful and non-truthful auctions\, for designing a
 pproximately revenue-optimal mechanisms for multi-item additive auctions. 
 Given a (not necessarily truthful) single-item auction format satisfying c
 ertain technical conditions\, we run simultaneous item auctions augmented 
 with a personalized entry fee that each bidder must pay before accessing t
 he auction. The entry fee depends only on the prior distribution of bidder
  types\, and in particular\, is independent of the realized bids.\nWe boun
 d the revenue of the resulting two-part tariff mechanism using a novel geo
 metric lemma that enables us to provide revenue guarantees for many common
  non-truthful auctions that previously had none. Our framework can be used
  with many common auction formats\, such as simultaneous first-price\, sim
 ultaneous second-price\, and simultaneous all-pay auctions. For all-pay au
 ctions\, we prove that the resulting mechanism is also credible in the sen
 se that the auctioneer cannot benefit by deviating from the stated mechani
 sm after observing agent bids. This is the first static credible mechanism
  for multi-item additive auctions that guarantees a constant factor of the
  optimal revenue.\nA paper based on this joint work with Costis Daskalakis
 \, Maxwell Fishelson\, Brendan Lucier\, and Vasilis Syrgkanis was presente
 d at the Twenty-First ACM Conference on Economics and Computation (EC 2020
 ). The arXiv version of the paper is available at https://arxiv.org/abs/20
 02.06702\n
URL:https://www.tcs.tifr.res.in/web/events/1073
DTSTART;TZID=Asia/Kolkata:20200728T140000
DTEND;TZID=Asia/Kolkata:20200728T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1074
DTSTAMP:20230914T125949Z
SUMMARY:Average Sensitivity of Graph Algorithms
DESCRIPTION:Speaker: Nithin Varma (University of Haifa\, Israel)\n\nAbstrac
 t: \nAbstract:  In modern applications of graph algorithms\, where the gr
 aphs of interest are large and dynamic\, it is unrealistic to assume that 
 an input representation contains the full information of a graph being stu
 died. For example\, consider a social network\, where a vertex corresponds
  to a user and an edge corresponds to a friendship relation.\n\nIt is reas
 onable to assume that users do not always update new friendships on the so
 cial network\, and that sometimes they do not fully disclose their friends
 hip relations for security or privacy reasons.\n\nThis motivates the desig
 n of graph algorithms that\, in spite of being given only a (large) subgra
 ph as input\, output solutions that are close to the solutions output when
  the whole graph is available. In this talk\, I will introduce a notion of
  sensitivity of graph algorithms that formalizes this desirable feature. A
 fter discussing the basic properties of our sensitivity definition\, I wil
 l give an overview of our main results\, and present the key ideas used in
  the design of our algorithm with low sensitivity for the global minimum c
 ut problem.\n\nThis is a joint work with Yuichi Yoshida.\n
URL:https://www.tcs.tifr.res.in/web/events/1074
DTSTART;TZID=Asia/Kolkata:20200808T160000
DTEND;TZID=Asia/Kolkata:20200808T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1075
DTSTAMP:20230914T125949Z
SUMMARY:Coordination Over Networks: Shared Randomness\, Security\, and Inte
 raction
DESCRIPTION:Speaker: Gowtham Kuri (TIFR)\n\nAbstract: \nAbstract-In a coord
 ination problem\, users in a network observing correlated inputs collabora
 te to evaluate possibly randomized functions of the inputs. Problems of th
 is kind have been widely studied in the information theory literature. It 
 finds applications in several diverse areas such as in parallel processing
 \, cooperative game theory\, distributed control\, function computation in
  networks. The focus of many of the works in the literature has been on th
 e amount of communication needed to achieve coordination. In practice\, se
 veral other aspects are also of interest such as the amount and form of sh
 ared/correlated randomness available\, topology of the network used\, and 
 security.  \nIn this talk\, we present a systematic study of various suc
 h aspects\, namely\, shared randomness\, security\, and interaction in add
 ition to the amount of communication needed. To this end\, the first probl
 em we study is a distributed sampling problem where a set of processors wa
 nt to output correlated sequences of random variables with the help of a c
 oordinator which has access to several independent sources of randomness a
 nd each processor has access to a subset of these sources. We characterize
  optimal communication and/or shared randomness rates in various cases of 
 this setting.\nIn the second problem\, we study interactive secure functio
 n computation. The privacy requirement is that the communication should no
 t reveal to either user any extra information about the other user’s inp
 ut and output other than what can be inferred from the user’s own input 
 and output. We give single-letter expressions for the asymptotic rate regi
 ons. Further\, we analyse the role of common randomness and interaction. I
 n secure function computation\, in some settings\, it might be reasonable 
 to give away a certain amount of information about the inputs but not abou
 t some specific functions of the inputs which the users want to keep priva
 te. We study such settings also.\n
URL:https://www.tcs.tifr.res.in/web/events/1075
DTSTART;TZID=Asia/Kolkata:20200810T103000
DTEND;TZID=Asia/Kolkata:20200810T113000
LOCATION:Join Zoom Meeting https://zoom.us/j/98083276706?pwd=cm85dHNQU0tSKz
 c1SndzYlZKL3ZxZz09  Meeting ID: 980 8327 6706 Passcode: 468237
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1076
DTSTAMP:20230914T125949Z
SUMMARY:Identifying some necessary conditions for a function to be Boolean
DESCRIPTION:Speaker: Nikhil Mande (Georgetown University\, Washington\, D.C
 .)\n\nAbstract: \nThe seminar will happen via Google meet.\n\nAbstract:  E
 very Boolean function $f : \\mathbb{F}_2^n \\to \\{-1\, 1\\}$ has a unique
  Fourier representation\, that is\, $f = \\sum_{\\alpha \\in \\mathbb{F}_2
 ^n}\\hat{f}(\\alpha)\\chi_{\\alpha}$. One can obtain the following identit
 ies using elementary techniques.\n\n1) Parseval's identity: $\\sum_{\\alph
 a \\in \\mathbb{F}_2^n}\\hat{f}(\\alpha)^2 = 1$.\n2) For all $\\gamma \\ne
 q 0^n$\, we have $\\sum_{(\\alpha_1\, \\alpha_2) \\in \\mathbb{F}_2^n \\ti
 mes \\mathbb{F}_2^n : \\alpha_1+\\alpha_2=\\gamma}\\hat{f}(\\alpha_1)\\hat
 {f}(\\alpha_2)=0$. Henceforth\, we refer to these conditions as Titsworth'
 s conditions.\n\nLet $\\mathcal{S}$ denote the Fourier support of $f$\, th
 at is\, the set of elements of $\\mathbb{F}_2^n$ that have non-zero Fourie
 r coefficients. Titsworth's conditions can be seen to imply that for every
  pair $(\\alpha_1\, \\alpha_2)$ of elements in $\\mathcal{S}$\, there must
  exist at least one other pair $(\\beta_1\, \\beta_2)$ of elements in $\\m
 athcal{S}$ such that $\\alpha_1 \\oplus \\alpha_2 = \\beta_1 \\oplus \\bet
 a_2$. We investigate whether this condition in itself is sufficient for $\
 \mathcal{S}$ to be the Fourier support of a Boolean function.\n\nOnly basi
 c mathematical familiarity will be assumed. I will cover the required prer
 equisites from Fourier analysis of Boolean functions in the beginning of t
 he talk.\n\nBased on joint work with Swagato Sanyal (IIT Kharagpur). Link 
 to full paper: https://arxiv.org/abs/2008.00266\n
URL:https://www.tcs.tifr.res.in/web/events/1076
DTSTART;TZID=Asia/Kolkata:20200815T110000
DTEND;TZID=Asia/Kolkata:20200815T120000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1077
DTSTAMP:20230914T125949Z
SUMMARY:Guarding Polygons via CSPs
DESCRIPTION:Speaker: Akanksha Agrawal (Ben-Gurion University\, Israel)\n\nA
 bstract: \nAbstract: Introduced by Klee in 1973\, the Art Gallery problem 
 asks the following question. Given the top view of an art gallery in the f
 orm of a polygon\, how many guards does one need to place inside the art g
 allery so that each wall is visible to at least one of them? It is easy to
  see that for convex polygons\, one guard is always sufficient. The proble
 m becomes nontrivial when the polygon has reflex vertices (vertices whose 
 interior angle is more than 180 degrees).\n\nIn this talk\, we study some 
 variants of the Art Gallery problem. Using structural properties of almost
  convex polygons\, we reduce an Art Gallery variant to a CSP (Constraint S
 atisfaction Problem) whose constraints have arity two and involve monotone
  functions. We then obtain a polynomial-time algorithm for the CSP\, and c
 onsequently for the Art Gallery variant when parameterized by the number o
 f reflex vertices. This is joint work with Kristine Knudsen\, Daniel Loksh
 tanov\, Saket Saurabh\, and Meirav Zehavi.\n\n(A condensed version of this
  talk was presented at the TCS Women Spotlight Workshop at STOC 2020.)\n
URL:https://www.tcs.tifr.res.in/web/events/1077
DTSTART;TZID=Asia/Kolkata:20200821T171500
DTEND;TZID=Asia/Kolkata:20200821T181500
LOCATION:Zoom link: https://zoom.us/j/92834710011?pwd=WURSa3JsRVpJYWhONEExY
 TdDcENDQT09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1078
DTSTAMP:20230914T125949Z
SUMMARY:Communication Complexity and Quantum Machine Learning via Query Com
 plexity
DESCRIPTION:Speaker: Suhail Sherif\n\nAbstract: \nQuery algorithms are ever
 ywhere. Gradient Descent is a well-known algorithm that queries the gradie
 nt of a hidden function and moves towards the minimum of the function. Sho
 r's factoring algorithm is based on a quantum query algorithm for period f
 inding. Many interesting computational tasks are indeed query tasks. Howev
 er\, the study of query complexity of total functions also leads us to int
 eresting mathematical insights\, such as the degree of a function being po
 lynomially related to its query complexity.\n\nIn this thesis we show a fe
 w related results.\n\n1. In the context of randomized communication comple
 xity and randomized parity decision tree (RPDT) complexity\, we prove that
  the analogues of the mathematical insight stated above do not hold. This 
 disproves multiple long-standing conjectures in communication complexity.\
 n\n2. Our results above originated in the RPDT world and were then transla
 ted to the communication world. However\, we also have stronger results in
  the RPDT world that we could not translate yet. We pose a fundamental con
 jecture that would imply that the stronger results do hold in the communic
 ation world as well.\n\n3. We analyze the query complexity of minimizing a
  convex function in a bounded region when given access to function value a
 nd gradient oracles. Projected Gradient Descent is known to be optimal for
  deterministic and randomized query algorithms (although the randomized lo
 wer bound is for a limited range of parameters). We provide a randomized l
 ower bound that works for the optimal range of parameters. We also prove t
 hat projected gradient descent is optimal among quantum query algorithms.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1078
DTSTART;TZID=Asia/Kolkata:20200824T103000
DTEND;TZID=Asia/Kolkata:20200824T113000
LOCATION:Zoom link for the meeting.     https://zoom.us/j/96554737206?pwd=R
 zBsVE56TnV2dTZ0dlNmaFp5MFRzZz09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1079
DTSTAMP:20230914T125949Z
SUMMARY:An Asymptotic Study of Financial Systems - Algorithms and  Analysis
DESCRIPTION:Speaker: Anand Deo\n\nAbstract: \nOver the past few decades\, a
 symptotic study of financial systems has become an integral part of practi
 cal decision making and analytics. Realistic financial systems are complex
 \, and undesirable events in them are often rare. In order to gain more in
 sights into their behaviour\, it is important to develop structural simpli
 fications and efficient computational algorithms for rare event analysis. 
 In this talk\, we undertake a detailed study of these aspects\, and develo
 p structural insights on a number of financial systems of practical intere
 st.\n\nIn the first part\, we consider two problems related to rare event 
 analysis:\n\n1) The estimation of default probabilities of financial firms
  from data is an important problem which has received significant attentio
 n over the past two decades. We discuss the development of a closed form\,
  interpretable parameter estimation technique for predicting defaults of f
 inancial firms. Typically\, one uses Maximum Likelihood Estimation (MLE) f
 or predicting the firm default probabilities. We prove that our estimator 
 is almost as accurate as the MLE for a realistic sample of financial data.
  Further since our estimator is closed form\, it is significantly faster t
 han MLE. Finally\, we demonstrate that unlike the MLE our estimator also g
 ives interesting structural insights - specifically\, we show that from th
 e standpoint of default prediction\, collecting covariate data just before
  occurrence of default is sufficient to estimate probabilities.\n\n2) Buil
 ding upon the well established notions of multivariate regular variation a
 nd large deviations theory\, we derive a unified framework\, in which tail
  analysis of a large class of stochastic loss functions can be performed. 
 Within this framework\, assuming the underlying stochasticity is heavy tai
 led\, we develop a data-driven estimator for tail exceedences of a large c
 lass of financial losses\, and applying it to a tail risk-constrained port
 folio optimisation problem\, showcase superior performance over the state 
 of the art. Additionally\, assuming oracle access to the densities of loss
  causing covariates\, we develop a self-replicating\, provably accurate im
 portance sampling algorithm to estimate rare event probabilities over a va
 riety of covariate/loss structures.\n\nIn the latter part of the talk\, we
  develop a limiting representation for an interconnected banking network i
 n presence of partial information. Practical banking networks are large an
 d complicated\,  and one searches for simple limiting representations (as 
 the network size goes to infinity). We characterise the wealths of banks i
 n a large network in terms of a simple\, one dimensional distributional fi
 xed point\, which we show is amenable to simulation. While such fixed poin
 t representations have been well studied when the network is of a finite s
 ize\, to the best of our knowledge\, our work is the first to provide a si
 mplified limiting representation.\n
URL:https://www.tcs.tifr.res.in/web/events/1079
DTSTART;TZID=Asia/Kolkata:20200827T103000
DTEND;TZID=Asia/Kolkata:20200827T113000
LOCATION:Zoom link for meeting.         https://zoom.us/j/97134023137?pwd=b
 XJwTkFHNFQxcDkyR2JaMkVaTk5WQT09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1080
DTSTAMP:20230914T125949Z
SUMMARY:Directed Information and Pearl's Causal Calculus
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nThis will be a tweaked ver
 sion of my Qualifier talk. I will mostly focus on:\n1. The notion of inter
 ventional distributions (as defined by Judea Pearl) and how they can be us
 ed to identify causal linkages.\n2. How directed information can serve as 
 a measure of causality.\n3. How conditional directed information can be us
 ed to develop an information-theoretic version of Pearl's backdoor criteri
 on for identifying causality from passive observations.\n\nLink to the pap
 er: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6120270\n
URL:https://www.tcs.tifr.res.in/web/events/1080
DTSTART;TZID=Asia/Kolkata:20200828T171500
DTEND;TZID=Asia/Kolkata:20200828T181500
LOCATION:Zoom link: https://zoom.us/j/92834710011?pwd=WURSa3JsRVpJYWhONEExY
 TdDcENDQT09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1081
DTSTAMP:20230914T125949Z
SUMMARY:Minimizing the Sum of Age of Information and Transmission Cost unde
 r Stochastic Arrival Model
DESCRIPTION:Speaker: Kumar Saurav\n\nAbstract: \nWe consider a node-monitor
  pair\, where updates are generated stochastically (according to a known d
 istribution) at the node that it wishes to send to the monitor. The node i
 s assumed to incur a fixed cost for each transmission\, and the objective 
 of the node is to find the update instants so as to minimize a linear comb
 ination of AoI of information and average transmission cost. First\, we co
 nsider the Poisson arrivals case\, where updates have an exponential inter
 -arrival time for which we derive an explicit optimal online policy. Next\
 , for arbitrary distributions of inter-arrival time of updates\, we propos
 e a simple randomized algorithm that transmits any newly arrived update wi
 th a fixed probability (that depends on the distribution) or never transmi
 ts that update. The competitive ratio of the proposed algorithm is shown t
 o be a function of the variance and the mean of the inter-arrival time dis
 tribution. For some of the commonly considered distributions such as expon
 ential\, uniform\, and Rayleigh\, the competitive ratio bound is shown to 
 be 2.\n
URL:https://www.tcs.tifr.res.in/web/events/1081
DTSTART;TZID=Asia/Kolkata:20200904T171500
DTEND;TZID=Asia/Kolkata:20200904T181500
LOCATION:Zoom link:   https://zoom.us/j/92834710011?pwd=WURSa3JsRVpJYWhONEE
 xYTdDcENDQT09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1082
DTSTAMP:20230914T125949Z
SUMMARY:An algebraic algorithm for minimizing linearly representable submod
 ular functions
DESCRIPTION:Speaker: Rohit Gurjar (Indian Institute of Technology Bombay\nM
 umbai)\n\nAbstract: \nA set function f on the subsets of a set E is called
  submodular if it satisfies a natural diminishing returns property: for an
 y two subsets S \\subseteq T \\subseteq E and an element x outside T\, we 
 have f(T + x) - f(T) \\leq f(S+x) - f(S). \nSubmodular minimization proble
 m asks for finding the minimum value a given submodular function takes. Th
 ere are many combinatorial optimization problems that reduce to submodular
  minimization\, for example\, bipartite matching\, max flow min cut\, arbo
 rescences\, disjoint spanning trees etc. All these problems admit algebrai
 c algorithms\, i.e.\, algorithms involving matrix rank computations. One c
 an ask what is the most general class of submodular functions whose minimi
 zation admits an algebraic algorithm. Towards this\, we define the class o
 f 'linearly representable submodular functions (LRSF)'\, which is based on
  the rank functions of families of subspaces and captures all the above co
 mbinatorial examples.  We give an algebraic algorithm for minimizing LRSF.
 \n\nOur algebraic algorithm for this class of functions can be parallelize
 d\, and thus\, puts the problem of finding the minimizing set in the compl
 exity class randomized NC.  Further\, we derandomize our algorithm so that
  it needs only poly-logarithmic random bits. We also identify combinatoria
 l problems which are captured by LRSF minimization\, but any explicit alge
 braic algorithms were not given before.\n\nJoint work with Rajat Rathi.\n
URL:https://www.tcs.tifr.res.in/web/events/1082
DTSTART;TZID=Asia/Kolkata:20200915T144500
DTEND;TZID=Asia/Kolkata:20200915T154500
LOCATION:https://zoom.us/j/93694032340?pwd=WFh1dFFlZzhPUVlQelU5c3A2UUdTQT09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1083
DTSTAMP:20230914T125949Z
SUMMARY:Parity Games are solvable in quasipolynomial time
DESCRIPTION:Speaker: Ashutosh Shankar\n\nAbstract: \nA longstanding open pr
 oblem in computer science has been to show that parity games can be solved
  in polynomial time. In this talk\, I will be presenting a quasipolynomial
  time algorithm due to Parys (2019) which is a modification of Zielonka's 
 recursive algorithm (1998).\n
URL:https://www.tcs.tifr.res.in/web/events/1083
DTSTART;TZID=Asia/Kolkata:20200918T171500
DTEND;TZID=Asia/Kolkata:20200918T181500
LOCATION:https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1084
DTSTAMP:20230914T125949Z
SUMMARY:Mathematics of Neural Nets
DESCRIPTION:Speaker: Anirbit Mukherjee (Wharton School of the University of
  Pennsylvania\nPennsylvania\, United States.)\n\nAbstract: \nOne of the pa
 ramount mathematical mysteries of our times is to be able to explain the p
 henomenon of deep-learning i.e training neural nets. Neural nets can be ma
 de to paint while imitating classical art styles or play chess better than
  any machine or human ever and they seem to be the closest we have ever co
 me to achieving "artificial intelligence". But trying to reason about thes
 e successes quickly lands us into a plethora of extremely challenging math
 ematical questions - typically about discrete stochastic processes. Some o
 f these questions remain unsolved for even the smallest neural nets! In th
 is talk we will give a brief overview of the major themes of our work in t
 his direction in the last few years.\n \nFirstly we will give highlights o
 f some of our  major depth hierarchy theorems and landscape results about 
 neural nets. Then we will explain how for certain nets under mild distribu
 tional conditions our iterative algorithms like ``Neuro-Tron"\, which do n
 ot use a gradient oracle\, can be proven to train nets in the infinity-nor
 m loss - using as much time/sample complexity as expected from gradient ba
 sed methods but in regimes where usual algorithms like (S)GD remain unprov
 en. Our theorems include the particularly challenging regime of dealing wi
 th non-realizable data while the net is of finite size. Next we will brief
 ly look at our first-of-its-kind results about sufficient conditions for f
 ast convergence of a standard adaptive gradient deep-learning algorithm\, 
 the RMSProp. \n\nIn the second half of the talk\, we will focus on the rec
 ent rise of the PAC-Bayesian technology in being able to explain the low r
 isk of certain over-parameterized nets on standardized tests. We will pres
 ent our recent results in this domain which give bounds which empirically 
 supersede some of the existing theoretical benchmarks in this field and th
 is we achieve via our new proofs about the key property of noise resilienc
 e of nets. \n \nThis is joint work with Amitabh Basu (JHU)\, Ramchandran M
 uthukumar (JHU)\, Jiayao Zhang (UPenn)\, Dan Roy (UToronto\, Vector Instit
 ute)\, Pushpendre Rastogi (JHU\, Amazon)\, Soham De (DeepMind\, Google)\, 
 Enayat Ullah (JHU)\, Jun Yang (UToronto\, Vector Institute) and Anup Rao (
 Adobe).\n \nBio: Anirbit Mukherjee finished his Ph.D. in applied mathemati
 cs at the Johns Hopkins University advised by Prof. Amitabh Basu. He is no
 w a post-doc at Wharton (UPenn)\, Statistics with Prof. Weijie Su. He spec
 ializes in deep-learning theory and has been awarded 2 fellowships from JH
 U for this research - the Walter L. Robb Fellowship and the inaugural Math
 ematical Institute for Data Science Fellowship. Earlier\, he was a researc
 her in Quantum Field Theory\, while doing his undergrad in physics at the 
 Chennai Mathematical Institute (CMI) and masters in theoretical physics at
  the Tata Institute of Fundamental research (TIFR).\n
URL:https://www.tcs.tifr.res.in/web/events/1084
DTSTART;TZID=Asia/Kolkata:20200922T160000
DTEND;TZID=Asia/Kolkata:20200922T170000
LOCATION:Zoom meeting:   https://zoom.us/j/97246120231?pwd=OGhsUTY4Unpyblkr
 cUxHMnlvbGxmdz09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1085
DTSTAMP:20230914T125949Z
SUMMARY:Speed Scaling in Networks
DESCRIPTION:Speaker: Rahul Vaze\n\nAbstract: \nThe speed scaling problem ha
 s been widely studied in the literature\, where there is a single server o
 r a parallel bank of servers with variable speed. Choosing speed s\, incur
 s a power cost given by a convex function P(s)\, whose integral is the tot
 al energy consumed. The problem is to find the optimal service speed/rate 
 for servers that minimizes a linear combination of the flow time (total de
 lay) and total energy. In this work\, we take the first steps towards desi
 gning speed scaling algorithms for a network of servers. The network is de
 scribed by a directed acyclic graph\, where there are multiple sources tha
 t wish to send packets to their respective destinations. Algorithms are de
 rived for both the worst case and stochastic job arrivals setting\, whose 
 competitive ratio depends only on the power functions and path diversity i
 n the network\, but is independent of the workload\, and number of nodes o
 f the network.\n
URL:https://www.tcs.tifr.res.in/web/events/1085
DTSTART;TZID=Asia/Kolkata:20200925T113000
DTEND;TZID=Asia/Kolkata:20200925T123000
LOCATION:Zoom Meeting https://zoom.us/j/7418257209?pwd=SGhITU5nYVBHRWhhbjc4
 VXdrZjNYZz09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1086
DTSTAMP:20230914T125949Z
SUMMARY:The Kullback-Leibler Upper Confidence Bound (KLUCB) Algorithm for r
 egret minimization in K-armed bandits
DESCRIPTION:Speaker: Anirban Bhattacharjee\n\nAbstract: \nThe K-armed bandi
 t problem is a sequential decision making problem wherein one has to seque
 ntially sample from a given set of K probability distributions (belonging 
 to a known family) informally called 'arms of the bandit'. The goal is to 
 minimize the total opportunity cost of not selecting the arm with the high
 est expected reward\, called the regret. We shall look at the Kullback-Lei
 bler Upper Confidence Bound (KLUCB) Algorithm for regret minimization in K
 -armed bandits\, and see how it meets the lower bound on expected regret f
 or our problem.\n
URL:https://www.tcs.tifr.res.in/web/events/1086
DTSTART;TZID=Asia/Kolkata:20200925T171500
DTEND;TZID=Asia/Kolkata:20200925T181500
LOCATION:Zoom link:  https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0v
 c0ZHcEt0Zz09
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1087
DTSTAMP:20230914T125950Z
SUMMARY:Hardness Characterisations and Size-Width Lower Bounds for QBF Reso
 lution
DESCRIPTION:Speaker: Meena Mahajan (IMSc\, Chennai)\n\nAbstract: \nThis tal
 k will start with an overview of the relatively young field of QBF proof c
 omplexity\, explaining the QBF proof system QURes\, and an assessment of e
 xisting lower bound techniques. In the main part of the talk\, I will desc
 ribe a characterisation of QURes proof size in terms of a model in circuit
  complexity called term decision lists\, yielding very direct connections 
 between circuit lower bounds and QURes proof size lower bounds. Joint work
  with Olaf Beyersdorff\, Joshua Blinkhorn\, Tomáš Peitl.\nYouTube Live :
  https://www.youtube.com/watch?v=Zn7ZzaELF6A\n
URL:https://www.tcs.tifr.res.in/web/events/1087
DTSTART;TZID=Asia/Kolkata:20200929T160000
DTEND;TZID=Asia/Kolkata:20200929T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1088
DTSTAMP:20230914T125950Z
SUMMARY:Convex Set Disjointness\, Distributed Learning of Halfspaces\, and 
 Linear Programming
DESCRIPTION:Speaker: Shay Moran (Technion)\n\nAbstract: \nDistributed learn
 ing protocols are designed to train on distributed data without gathering 
 it all on a single centralized machine\, thus contributing to the efficien
 cy of the system and enhancing its privacy.\nWe study a central problem in
  distributed learning\, called Distributed Learning of Halfspaces:\nlet U 
 \\subset R^d be a known domain of size n and let h:R^d —> R be an unknow
 n target affine function. A set of examples {(u\,b)} is distributed betwee
 n several parties\, where u \\in U is a point and b = sign(h(u)) \\in {-1\
 , +1} is its label.\nThe parties' goal is to agree\, using minimum communi
 cation\, on a classifier f: U—>{-1\,+1} such that f(u)=b for every input
  example (u\,b). (In practice\, the finite domain U is defined implicitly 
 by the representation of d-dimensional vectors which is used in the protoc
 ol.)\nWe establish a (nearly) tight bound of ~θ(d*log n) on the communica
 tion complexity of the problem of distributed learning of halfspaces in th
 e two-party setting.\nSince this problem is closely related to the Convex 
 Set Disjointness problem in communication complexity and the problem of Di
 stributed Linear Programming in distributed optimization\, we are able to 
 derive upper and lower bounds of ~O(d^2\\log n) and ~Ω(d\\log n) for both
  of these basic problems as well.\nOur main technical contribution lies in
  the design and analysis of the protocols which imply the upper bounds.\nT
 o this end\, we introduce a technique called Halfspace Containers\, allowi
 ng for a compressed approximate representation of every halfspace.\nHalfsp
 ace containers may be of independent interest and are closely related to b
 racketing numbers in statistics and to hyperplane cuttings in discrete geo
 metry.\n
URL:https://www.tcs.tifr.res.in/web/events/1088
DTSTART;TZID=Asia/Kolkata:20201006T160000
DTEND;TZID=Asia/Kolkata:20201006T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1089
DTSTAMP:20230914T125950Z
SUMMARY:Diophantine Sets and Computability
DESCRIPTION:Speaker: Prabhat Kumar Jha\n\nAbstract: \nDiophantine sets are 
 defined using Diophantine equations. These sets are important and ubiquito
 us in number theory.\nRecursively enumerable sets are defined using models
  of computation (Lambda calculus\, Turing machines\, etc). These sets are 
 studied in computability/recursion theory.\nIn this talk\, we will see an 
 equivalance between these two kind of sets emerging from two different the
 ories. This result is due to Matiyasevich and is known as MRDP theorem.\nT
 here are many interesting corollaries of this result including Godel's inc
 ompleteness theorem and undecidability of Diophantine equations.\nZoom lin
 k: https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09.\n
URL:https://www.tcs.tifr.res.in/web/events/1089
DTSTART;TZID=Asia/Kolkata:20201009T171500
DTEND;TZID=Asia/Kolkata:20201009T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1090
DTSTAMP:20230914T125950Z
SUMMARY:Network Oblivious Transfer
DESCRIPTION:Speaker: Varun Narayanan\n\nAbstract: \nSecure message transmis
 sion and Byzantine agreement have been studied extensively in incomplete n
 etworks. However\, information theoretically secure multiparty computation
  (MPC) in incomplete networks is less well understood. In this paper\, we 
 characterize the conditions under which a pair of parties can compute obli
 vious transfer (OT) information theoretically securely against a general a
 dversary structure in an incomplete network of reliable\, private channels
 . We provide characterization for semi-honest model of corruption. A conse
 quence of our results is a complete characterization of networks in which 
 a given subset of parties can compute any functionality securely with resp
 ect to an adversary structure in the semi-honest case.\n
URL:https://www.tcs.tifr.res.in/web/events/1090
DTSTART;TZID=Asia/Kolkata:20201013T140000
DTEND;TZID=Asia/Kolkata:20201013T153000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1091
DTSTAMP:20230914T125950Z
SUMMARY:Some Derandomized Constructions in Quantum Information Processing
DESCRIPTION:Speaker: Aditya Nema\n\nAbstract: \nRandomness is a vital tool 
 and resource in both classical and quantum information processing. However
 \, constructing random bits is expensive\, and hence minimising their use 
 is desirable. Several tools have been developed in classical computing for
  this purpose. Two such tools are expanders and k-wise independent random 
 variables\, and they have already found many applications in classical com
 puting. In this thesis we investigate the quantum analogues of these two t
 ools for quantum information processing tasks.\nIn quantum information pro
 cessing\, algorithms are often modeled by unitary operators and randomness
  enters the picture from the choice of random unitary operators\, much lik
 e randomness in classical information processing. Existential proofs in in
 formation processing applications are almost always based on unitary matri
 ces drawn from the Haar probability measure on the unitary group (formalis
 ation of the uniform measure on the unitary group). However\, an n-qubit u
 nitary is described by 4^n real parameters\, and thus cannot be efficientl
 y approximated using a sub-exponential amount of time or randomness. This 
 has led to the construction of efficient pseudo-random ensembles\nof unita
 ries which emulate the Haar measure\, up to the first t-moments\, for cert
 ain applications [Harrow\, Low 2009]. Such constructions are referred to a
 s unitary t-designs. It is known that there are exact unitary 't'-designs 
 for any t [Kuperberg\, 2006]. The advantage of using these designs is that
  approximate unitary t-designs can be efficiently constructed for t = poly
 (log dimension) [Brandao et al. 2012\, Sen 2018].\nIn this thesis we apply
  these designs for the following tasks:\n1. Showing that the minimum outpu
 t Renyi p-entropy\, for all p >= 1\, of quantum channels is subadditive. R
 enyi 1-entropy is the well known von Neumann entropy and its subadditivity
  leads to quantum channels with superadditive classical Holevo capacity [S
 hor 2004]. We prove for the first time that approximate unitary n^{2/3}-de
 signs lead to a quantum channel with superadditive classical Holevo capaci
 ty\;\n2. Efficient estimation of average gate fidelity of a quantum logic 
 gate using few random bits\, better than the state of the art\;\n\n3. Conc
 entration of measure for non-catalytic decoupling theorem in quantum infor
 mation theory\, using an approximate t-design for a suitable value of t\, 
 beating the state of the art for relative thermalisation under certain rea
 sonable assumptions.\nAlthough the unitary t-designs used in the above wor
 ks have t larger than what is known to be efficiently implementable\, yet 
 in all cases they lead to significant savings in the number of random bits
  required vis-a-vis Haar random unitaries. Thus\, all the three works can 
 be thought of as steps towards their respective derandomisations.\n-------
 ------------\nZoom Meeting https://zoom.us/j/91958942801?pwd=QzdyN2RXbE1RQ
 ko1bVpMZGluYVdNUT09     Meeting ID: 919 5894 2801 Passcode: 631121\n
URL:https://www.tcs.tifr.res.in/web/events/1091
DTSTART;TZID=Asia/Kolkata:20201016T133000
DTEND;TZID=Asia/Kolkata:20201016T143000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1092
DTSTAMP:20230914T125950Z
SUMMARY:Partial Function Extension with Applications to Learning and Proper
 ty Testing
DESCRIPTION:Speaker: Gunjan Kumar\n\nAbstract: \nPartial function extension
  is a basic problem that underpins multiple research topics in optimizatio
 n\, including learning\, property testing\, and game theory. Here\, we are
  given a partial function consisting of $n$ points from a domain and a fun
 ction value at each point. Our objective is to determine if this partial f
 unction can be extended to a function defined on the domain\, that additio
 nally satisfies a given property\, such as linearity. We formally study pa
 rtial function extension for various complement-free functions.\n\nOur con
 tributions are twofold. Firstly\, for the properties studied\, we give a c
 ombinatorial characterization and bounds on the complexity of partial func
 tion extension.  Secondly\, we develop new connections between partial fun
 ction extension and learning and property testing\, and use these to give 
 new results for these problems.\n\nZoom link:  https://zoom.us/j/915860682
 03?pwd=Sjk1T1lhR1lYVUhidHN2VVRXeFJoZz09\n
URL:https://www.tcs.tifr.res.in/web/events/1092
DTSTART;TZID=Asia/Kolkata:20201020T140000
DTEND;TZID=Asia/Kolkata:20201020T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1093
DTSTAMP:20230914T125950Z
SUMMARY:Learning arithmetic circuits in the average case via lower bounds
DESCRIPTION:Speaker: Ankit Garg (Microsoft Research\, Bangalore)\n\nAbstrac
 t: \nThe problem of learning arithmetic circuits is the following: given a
  polynomial as a black box that is promised to have a small arithmetic cir
 cuit computing it\, can we find this arithmetic circuit? This problem is h
 ard in the worst case and so previous works have focused on regimes where 
 the NP-hardness doesn't kick in (e.g. constant top fan-in etc.). We focus 
 on the average case where one assumes certain non-degeneracy assumptions o
 n the circuit (formally these amount to assuming the circuit parameters li
 e outside a certain variety and hence if they are chosen randomly accordin
 g to any reasonable distribution\, the non-degeneracy condition is satisfi
 ed whp). Kayal and Saha gave a meta framework (in a rudimentary form) or d
 esigning these algorithms for circuit classes where we have lower bounds. 
 They carried this out for depth 3 circuits (sums of products of linear for
 ms) and we (in joint work with Kayal and Saha) streamline their meta frame
 work and carry it out for depth 4 powering circuits (sums of powers of low
  degree polynomials). I will talk about the meta framework and then about 
 our specific results. I will also talk about a potential application to le
 arning mixtures of general Gaussians.\nYouTube live: https://www.youtube.c
 om/watch?v=qP1M8jmXnzc\n
URL:https://www.tcs.tifr.res.in/web/events/1093
DTSTART;TZID=Asia/Kolkata:20201020T160000
DTEND;TZID=Asia/Kolkata:20201020T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1094
DTSTAMP:20230914T125950Z
SUMMARY:A Provably Convergent and Practical Algorithm for Min-max Optimizat
 ion with Applications to GANs
DESCRIPTION:Speaker: Sushant Vijayan\n\nAbstract: \nAlgorithms for finding 
 min-max equilibrium points in a zero sum game often exhibit cyclic behavio
 r and non-convergence. The authors define a new solution concept for the z
 ero sum game  played through stochastic gradient descent (and similar suc
 h methods) and propose an algorithm which converges with very high probabi
 lity. The equilibrium point is reached in time polynomial in dimension and
  smoothness parameters of the function. Importantly no convexity or concav
 ity in either players control is assumed and the convergence is independen
 t of the initialization point.\n\nZoom link:https://zoom.us/j/98132227553?
 pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1094
DTSTART;TZID=Asia/Kolkata:20201023T171500
DTEND;TZID=Asia/Kolkata:20201023T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1095
DTSTAMP:20230914T125950Z
SUMMARY:Forecasting and the complexity of randomized algorithms
DESCRIPTION:Speaker: Eric Blais (University of Waterloo)\n\nAbstract: \nRan
 domness is a remarkably powerful tool in the design of algorithms. By givi
 ng algorithms the ability to use random bits and letting them err with som
 e small  probability\, we can solve many computational problems with rema
 rkable efficiency. However\, even the most basic questions about randomize
 d algorithms have proven to be remarkably challenging\, and many of those 
 questions even remain open to this day.\nIn this talk\, we will explore th
 e notion of forecasting algorithms\, a slight variant on the usual model o
 f randomized algorithms where the algorithm must generate a confidence sco
 re along with its output. We will see how forecasting algorithms allow us 
 to bypass some of the inherent difficulties in the analysis of bounded-err
 or randomized algorithms\, and lead to new developments on some of fundame
 ntal problems related to the composition conjecture for query complexity a
 nd to the minimax lemma.\nThis talk will cover material from joint work wi
 th Shalev Ben-David that can be found at https://arxiv.org/abs/2002.10802 
 and https://arxiv.org/abs/2002.10809.\n
URL:https://www.tcs.tifr.res.in/web/events/1095
DTSTART;TZID=Asia/Kolkata:20201027T160000
DTEND;TZID=Asia/Kolkata:20201027T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1096
DTSTAMP:20230914T125950Z
SUMMARY:Math and Informatics\, ever more fruitful interactions
DESCRIPTION:Speaker: Gérard Berry (French Académie des sciences)\n\nAbstr
 act: \nThe relation between math and algorithmics is very old. In a sense\
 , one can even argue that mathematics was created to show that some alread
 y known algorithms worked in all cases and not only on some examples. Chur
 ch and Turing\, creators of the lambda-calculus and computability theory w
 ere mathematicians. Informatics was really born later with the introductio
 n of computers\, for which mathematicians played an important role. In the
  70's\, computer algebra was developed\, as well as the formal semantics o
 f programming languages and automatic program analysis techniques. But the
  cooperation between both sciences has deepened quickly in the last 20 yea
 rs\, with mutual enrichment. We will show this with a variety of examples 
 : the systematic development of randomized and probabilistic algorithms to
  handle massive data\, the use of boolean satisfiability (SAT) systems to 
 solve open problems in number theory\, the development of powerful proof a
 ssistants for mechanizing large mathematical proofs using rich logics (Fei
 t-Thompson theorem\, Kepler conjectures)\, and finally\, the use of the sa
 me tools to perform mathematical proofs of the correctness of safety-criti
 cal computerized systems. Bio: Gérard Berry\, member of the French Acadé
 mie des sciences and Gold Medal of CNRS in 2014\, studied at Ecole Polytec
 hnique and Corps des Mines in Paris. He was researcher at Ecole des Mines 
 and Inria from 1970 to 2001\, Chief Scientist of the Esterel Technologies 
 company from 2001 to 2009\, Director of Research at Inria from 2009 to 201
 2\, before being appointed as Full Professor at Collège de France in 2012
  on the Algorithms\, Programs and Machine Chair\; he had previously held t
 here two yearly chairs in 2007-2008 and 2009-2010. He officially retired i
 n 2001. His main scientific contributions concern the formal development o
 f programming languages in relation with mathematical logic\, parallel and
  real-time programming\, high-level design of computer circuits and system
 s\, and formal verification of programs and circuits. He is the creator of
  the Esterel synchronous reactive language. Through his courses\, books an
 d conferences\, he is also active in the dissemination to a general audien
 ce of the new algorithmic way of thinking and acting. This virtual session
  is in the framework of the Itinerant Chair in India created by the French
  Institute in India ( http://ifindia.in/all-events/ ) in collaboration wit
 h Collège de France ( https://www.college-de-france.fr/site/college/index
 .htm ). In the heart of Paris\, Collège de France is a highly reputed Fre
 nch higher education and research establishment. Since the 16th century\, 
 it has been a forum for cutting-edge research and education in all fields 
 of knowledge\, from mathematical and natural sciences to social sciences a
 nd humanities. To know more about the Itinerant Chair in India : https://i
 findia.in/college-de-france/\nYouTube Live : https://youtu.be/cIfE0pSWU0E
 \n
URL:https://www.tcs.tifr.res.in/web/events/1096
DTSTART;TZID=Asia/Kolkata:20201103T160000
DTEND;TZID=Asia/Kolkata:20201103T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1097
DTSTAMP:20230914T125950Z
SUMMARY:Unravelling Dataset Biases
DESCRIPTION:Speaker: Mohit Lamba (Indian Institute of Technology\, Madras\n
 Chennai)\n\nAbstract: \nAs scientists and engineers\, we have long aimed a
 t solving real-time problems such as detecting and localizing objects seen
  by our video recorder or at least something like Pokemon's Animedex. But 
 in recent times\, this has translated to publishing slapdash papers wherei
 n the only gold standard is to beat some metric defined for a selected pro
 blem as seen in the Imagenet and Pascal VOC challenge. But how good the so
 -called incredible performance in such contrived situations generalizes in
  a real-world setting?  In this short talk\, we shall discuss several data
 set biases that occur in collecting a dataset aiming to emulate the real w
 orld and its consequence in narrowing down the research community's focus.
  Though we shall take specific case studies from the Computer Vision commu
 nity\, the hope is that the message will be equally relevant to all the di
 sciples and generate curiosity to question if we have lost our original pu
 rpose in a bid to break the previous benchmarks.\n\nZoom Link: https://zoo
 m.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1097
DTSTART;TZID=Asia/Kolkata:20201106T171500
DTEND;TZID=Asia/Kolkata:20201106T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1098
DTSTAMP:20230914T125950Z
SUMMARY:Fair Cake Division Under Monotone Likelihood Ratios
DESCRIPTION:Speaker: Siddharth Barman (Indian Institute of Science\nBangalo
 re)\n\nAbstract: \nThe cake-cutting problem provides a model for addressin
 g fair allocation of a divisible resource (metaphorically\, the cake) amon
 g agents with distinct preferences. Classic results of Stromquist (1980) a
 nd Su (1999) show that envy-free (fair) cake divisions are guaranteed to e
 xist under mild conditions. These strong existential results essentially f
 ollow from fixed-point theorems and stand without an algorithmic counterpa
 rt\; Stromquist (2008) has shown that an envy-free cake division with cont
 iguous pieces cannot be computed in bounded time. \n\nIn this talk I will 
 present a result which complements these existential (and non-constructive
 ) guarantees by way of developing efficient cake-cutting algorithms for a 
 broad class of valuations. In particular\, our algorithmic result holds wh
 en the agents' valuations are induced by linear translations of any log-co
 ncave function\, such as Gaussian\, exponential\, linear\, or binomial.\n\
 nJoint work with Nidhi Rathi. \n\nhttps://arxiv.org/abs/2006.00481\n\nhttp
 s://www.youtube.com/watch?v=uzc2ht4xPFU\n
URL:https://www.tcs.tifr.res.in/web/events/1098
DTSTART;TZID=Asia/Kolkata:20201110T160000
DTEND;TZID=Asia/Kolkata:20201110T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1099
DTSTAMP:20230914T125950Z
SUMMARY:Robust Algorithms for recovering planted structures in Semi-random 
 instances
DESCRIPTION:Speaker: Yash Khanna (Indian Institute of Science\, Bangalore)\
 n\nAbstract: \nIn this work\, we design algorithms for two fundamentally i
 mportant and classical graph problems in the planted setting. Both of thes
 e problems are NP-hard and the bounds known from the algorithmic front are
  either not fully understood\, or not much progress can be made because of
  tight lower bounds. Thus it is natural to consider semi-random models for
  these problems. These models are inspired from the seminal paper of Feige
  and Killian [FK01] and have been studied in numerous follow-up works with
  the latest ones by Steinhardt\, and McKenzie et al. [Ste17\, MMT20]. The 
 construction of our instance starts with an empty graph\, then an arbitrar
 y set of vertices (S) is chosen and either a dense graph or a clique (or a
 n independent set) is planted on it\, the subgraph on S x V-S is a random 
 graph\, while the subgraph on V-S might be a random\, arbitrary\, or some 
 special graph (depending on the model). Our algorithms are based on roundi
 ng semi-definite programs and our primary focus is on recovering (complete
 ly or partially) the planted structure (S) with high probability (over the
  randomness of the input). We give algorithms that exploit the geometry of
  the corresponding vectors (from the SDP) and are easy to design/analyse. 
 \n\nThe two problems which we study are:\n1. Densest k-Subgraph/Clique\nGi
 ven an undirected graph G\, the Densest k-Subgraph problem (DkS) asks to c
 ompute a subset S of V of cardinality k such that the weight of edges insi
 de S is maximized. This is a fundamental NP-hard problem whose approximabi
 lity\, inspite of many decades of research\, is yet to be settled. There i
 s a significant gap between the best known worst-case approximation factor
  of this problem [BCC+10] and the hardness of approximation for it (assumi
 ng the Exponential Time Hypothesis) [Man17]. We ask what are some easier i
 nstances of this problem? We propose some natural semi-random models of in
 stances with a planted dense subgraph\, and study approximation algorithms
  for computing the densest subgraph in them. There are many such random an
 d semi-random models which have been studied in the literature [BCC+10\, A
 me15\, HWX16\, BA19 etc.].\n2. Independent Set in Hypergraphs\nThe indepen
 dent set problem in graphs poses the following question: given a graph\, a
 nd a subset of vertices such that any two vertices of the set do not have 
 an edge between them. The maximization version of this problem features as
  one of the Karp's original twenty-one NP-complete problems ([Kar72]\, the
  clique problem instead of its complement\, the  independent set problem).
  The independent set problem is relatively well understood and by the famo
 us result of Håstad [Hås99]\, the lower and upper bounds of this problem
  are tight. Hypergraphs are a natural extension of graphs\, where each edg
 e is formed across a tuple of distinct vertices. For a graph\, each tuple 
 has a size\, two. To the best of our knowledge\, semi-random models on hyp
 ergraphs have not been studied so far. Studying classical problems like th
 ese on hypergraphs is naturally of theoretical as well as practical intere
 st. We study the algorithmic problems studied in McKenzie et al. [MMT20] a
 nd develop algorithms for them in the case of hypergraphs.\n\nNote: This i
 s joint work with Anand Louis and Rameesh Paul. Both of these e-prints wil
 l be up on arXiv soon.\n\nSpeaker Bio: Yash Khanna is a third (and final) 
 year M.Tech (Research) student in the Theory Group of CSA\, IISc Bangalore
 . His research interests include Algorithms and Complexity. He previously 
 graduated from BITS Pilani.\n-----------------\nZoom meeting link : https:
 //zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1099
DTSTART;TZID=Asia/Kolkata:20201113T171500
DTEND;TZID=Asia/Kolkata:20201113T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1100
DTSTAMP:20230914T125950Z
SUMMARY:Hitting Sets for Some Algebraic Models - Constructions and Conseque
 nces
DESCRIPTION:Speaker: Anamay Tengse\n\nAbstract: \nWe study the question of 
 constructing _hitting sets_ for polynomials computed by several algebraic 
 models. For a class of polynomials C\, hitting sets for C capture the prob
 lem of _deterministic_ blackbox PIT for C - checking if a polynomial from 
 C is zero by querying it on a few points. Formally\, a hitting set for a c
 lass C is a set H such that for every nonzero f in C\, there is some point
  h in H for which f(h) is nonzero. Owing to its close connections to the s
 earch of explicit hard polynomials\, finding efficient hitting sets for va
 rious classes of polynomials is a central question in algebraic complexity
  theory.\nOur contributions towards this question are as follows. The firs
 t set of our results extend the scope of known hitting set constructions t
 o other well studied algebraic models. Next\, we show that for any general
  enough algebraic model\, like circuits or formulas\, even a mild improvem
 ent to the trivial hitting sets for the model leads to almost efficient hi
 tting sets for it. Lastly\, we explore how hitting sets for a class of pol
 ynomials can assist us in _proving_ lower bounds against that class.\n
URL:https://www.tcs.tifr.res.in/web/events/1100
DTSTART;TZID=Asia/Kolkata:20201123T111500
DTEND;TZID=Asia/Kolkata:20201123T121500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1101
DTSTAMP:20230914T125950Z
SUMMARY:Optimal Control Problems with Symmetry Breaking Cost Functions
DESCRIPTION:Speaker: Rohit Gupta (University of Michigan)\n\nAbstract: \nSy
 mmetry reduction is a well studied subject in geometric mechanics\, where 
 symmetries are usually described as an invariance under an action of a Lie
  group. Symmetry breaking is also common in several physical contexts\, fr
 om classical mechanics to particle physics and in certain cases\, it is st
 ill possible to carry out symmetry reduction. The simplest example is the 
 heavy top dynamics (the motion of a rigid body with a fixed point in a gra
 vitational field)\, where due to the presence of gravity\, we get a Lagran
 gian that is SO(2)-invariant but not SO(3)-invariant\, contrary to what ha
 ppens for the free rigid body. Based on the ideas of symmetry reduction st
 udied in geometric mechanics\, symmetry reduction of optimal control probl
 ems (OCPs) for left-invariant control systems on Lie groups has been studi
 ed extensively over the past couple of decades and by exploiting these sym
 metries\, the system can be reduced to a lower-dimensional one or decouple
 d into subsystems. In this talk\, I will discuss symmetry reduction of OCP
 s for left-invariant control affine systems on Lie groups with partially b
 roken symmetries\, more specifically\, cost functions that break some but 
 not all of the symmetries. I will illustrate the theory with the motion pl
 anning problem of a controlled unicycle (a popular model used in robotics)
  in the presence of an obstacle\, where the symmetry breaking appears natu
 rally in the form of a barrier function.\n\nBio: Rohit Gupta received the 
 M.S.E. degree in Mechanical Engineering and the Ph.D. degree in Aerospace 
 Engineering from the University of Michigan in 2012 and 2016\, respectivel
 y. From January 2016 to August 2017\, he was a postdoctoral research assoc
 iate at the Institute for Mathematics and its Applications (IMA) at the Un
 iversity of Minnesota. From August 2017 to August 2018\, he was a postdoct
 oral research associate in the department of Mathematics at Michigan State
  University. From September 2018 to August 2019\, he was a postdoctoral re
 search fellow in the department of mechanical engineering at the Universit
 y of Michigan. From September 2019 to August 2020\, he was a postdoctoral 
 research fellow in the department of electrical engineering and computer s
 cience at the University of Michigan. His research interests include geome
 tric mechanics\, geometric control\, optimal control and optimization.\n
URL:https://www.tcs.tifr.res.in/web/events/1101
DTSTART;TZID=Asia/Kolkata:20201124T140000
DTEND;TZID=Asia/Kolkata:20201124T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1102
DTSTAMP:20230914T125950Z
SUMMARY:Degree vs Approximate Degree for Boolean Functions
DESCRIPTION:Speaker: Suhail Sherif\n\nAbstract: \nThe field of researching 
 Boolean functions can be summed up as\nBoolean functions: *exist*\nResearc
 hers: find out EVERYTHING\nThis has led to it being a very happening field
  with many elegant results and fascinating stories. The algebraic properti
 es of degree and approximate degree have played prominent roles in many of
  these. A couple of years before I was born\, Gotsman and Linial showed a 
 purely combinatorial reformulation of the `degree vs sensitivity' question
 .\nLast year Hao Huang shocked the world by proving this combinatorial sta
 tement with a linear algebraic argument that fits in a tweet.\nCome this y
 ear and the team of Scott Aaronson\, Shalev Ben-David\, Robin Kothari\, Sh
 ravas Rao and Avishay Tal have delved into this linear algebraic argument 
 and proved many other implications of it\, the one most interesting to me 
 being\napprox-degree(f) ≥ Ω(√degree(f))\nIt is a quite elementary pro
 of taking advantage of intuitive linear algebraic manipulations. This is w
 hat I intend to present in this student seminar.\n\nZoom Link:\nhttps://zo
 om.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1102
DTSTART;TZID=Asia/Kolkata:20201127T171500
DTEND;TZID=Asia/Kolkata:20201127T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1103
DTSTAMP:20230914T125950Z
SUMMARY:SNARGs and PPAD Hardness from Sub-exponential LWE
DESCRIPTION:Speaker: Prof. Dakshita Khurana (University of Illinois at Urba
 na-Champaign)\n\nAbstract: \nWe construct a succinct non-interactive publi
 cly-verifiable delegation scheme for any logspace uniform circuit under th
 e sub-exponential Learning With Errors (LWE) assumption. For a circuit C :
  {0\, 1}^N -> {0\, 1} of size S and depth D\, the prover runs in time poly
 (S)\, the communication complexity is D * polylog(S)\, and the verifier ru
 ns in time (D + N) * polylog(S). To obtain this result\, we introduce a ne
 w cryptographic primitive: lossy correlation-intractable hash functions. W
 e use this primitive to soundly instantiate the Fiat-Shamir transform for 
 a large class of interactive proofs\, including the interactive sum-check 
 protocol and the GKR protocol\, assuming the sub-exponential hardness of L
 WE. By relying on the result of Choudhuri et al. (STOC 2019)\, we also est
 ablish the sub-exponential average-case hardness of PPAD\, assuming the su
 b-exponential hardness of LWE. This is based on joint work with Ruta Jawal
 e\, Yael Tauman Kalai and Rachel Zhang.\nYouTube Link- https://www.youtube
 .com/watch?v=H7zwkYuILiQ\n
URL:https://www.tcs.tifr.res.in/web/events/1103
DTSTART;TZID=Asia/Kolkata:20201208T173000
DTEND;TZID=Asia/Kolkata:20201208T183000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1104
DTSTAMP:20230914T125950Z
SUMMARY:Optimization for scheduling and beyond\, a set covering view of sch
 eduling
DESCRIPTION:Speaker: Jatin Batra (CWI Amsterdam\, Netherlands)\n\nAbstract:
  \nScheduling provides an interesting context for optimization methods. Th
 is talk is about how a set covering viewpoint can provide powerful insight
 s into scheduling in many settings - minimizing response times on a single
  machine\, heterogenous scheduling on multiple machines\, diversification 
 in information retrieval etc. Along the way\, I will also illustrate conne
 ctions and improvements to classic set covering problems in the context of
  knapsacks\, geometric set cover and minimum-cuts. Along the way\, I will 
 show how Chernoff bounds can be improved for lower tails of Bernoulli dist
 ributions.\n
URL:https://www.tcs.tifr.res.in/web/events/1104
DTSTART;TZID=Asia/Kolkata:20201210T160000
DTEND;TZID=Asia/Kolkata:20201210T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1105
DTSTAMP:20230914T125950Z
SUMMARY:Off-policy evaluation in Reinforcement Learning using Linear Regres
 sion
DESCRIPTION:Speaker: Anirban Bhattacharjee\n\nAbstract: \nIn Reinforcement 
 Learning\, one often needs to evaluate a given policy using rewards observ
 ed by following another policy. This is called off-policy evaluation in Le
 arning Theory parlance. The traditional methods for off-policy evaluation 
 involve importance sampling\, which comes with certain drawbacks. We shall
  look at these drawbacks and how linear regression may be used instead to 
 overcome the same.\n\nZoom link: https://zoom.us/j/98132227553?pwd=K2cyQll
 KVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1105
DTSTART;TZID=Asia/Kolkata:20201211T171500
DTEND;TZID=Asia/Kolkata:20201211T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1106
DTSTAMP:20230914T125950Z
SUMMARY:Formalizing Finite Set Combinatorics in Type Theory
DESCRIPTION:Speaker: Abhishek Singh\n\nAbstract: \nMathematical proofs when
  written in conventional ways often contain imprecise definitions\, unstat
 ed background assumptions\, and inferential gaps in reasoning. In such cir
 cumstances\, it becomes difficult for a reviewer to determine whether the 
 given proof is correct or not.  Even if the theorem statement turns out t
 o be true\, judging it to be so could take a long time. A possible solutio
 n to this problem is to formalize mathematical results using Proof Assista
 nts. Proof Assistants are software tools built on top of a small and trust
 ed kernel that provides a formal language for writing mathematical stateme
 nts and their proofs. Hence\, formally verifying a mathematical theory usi
 ng a Proof Assistant can increase our confidence in the verified results. 
 However\, the task of formalizing mathematics using Proof Assistants prese
 nts some unique challenges\; both practical as well as theoretical. Theore
 tical challenges mostly arise because some trivially assumed axioms of cla
 ssical mathematics may not be provable in the core logic of the Proof Assi
 stant. On the other hand\, the practical difficulties of formalization mos
 tly arise because the machine-checkable proofs are significantly more deta
 iled than the corresponding paper proofs. In this talk\, we will address b
 oth these issues while presenting formal proofs of some key results from f
 inite set combinatorics. More precisely\, we present formalized libraries 
 of definitions and results on two important mathematical structures from c
 ombinatorics: (i) finite partially ordered sets\, and (ii) finite simple g
 raphs. These libraries have been formalized in the type theory of Coq Proo
 f Assistant.\n\nZoom Link:\nhttps://zoom.us/j/95365190349?pwd=ZENsRG1pbmVp
 V01nQ3BPRGJVZmZPdz09\nMeeting ID: 953 6519 0349\nPasscode: 993493\n
URL:https://www.tcs.tifr.res.in/web/events/1106
DTSTART;TZID=Asia/Kolkata:20201214T103000
DTEND;TZID=Asia/Kolkata:20201214T113000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1107
DTSTAMP:20230914T125950Z
SUMMARY:Accelerating Black Box Estimation of Distribution Tails Using Self 
 structuring Importance Samplers
DESCRIPTION:Speaker: Anand Deo\n\nAbstract: \nMotivated by the increasing a
 doption of models which facilitate greater automation in risk management a
 nd decision-making\, this talk presents a novel Importance Sampling (IS) s
 cheme for estimating distribution tails for a rich class of objectives mod
 elled with tools such as mixed integer linear programs\, deep neural netwo
 rks\, etc. A key challenge with the conventional efficient sampling approa
 ches in these settings is the need to intricately tailor the samplers base
 d on the underlying probability distribution and the objective. This chall
 enge is overcome in the proposed black-box scheme by automating the select
 ion of an effective IS density with a transformation that implicitly learn
 s and replicates the concentration properties observed in less rare sample
 s.  Despite its simple and scalable implementation\, this self structuring
  IS scheme achieves asymptotically optimal variance reduction across a spe
 ctrum of multivariate distributions involving light as well as heavy tails
 .\n\nThis approach is guided by a large deviations principle that brings o
 ut the phenomenon of self-similarity of optimal IS distributions in consid
 erable generality.  In addition to helping certify variance reduction\, th
 e large deviations principle serves as a tool for readily yielding new tai
 l risk asymptotics and algorithms in settings such as distribution network
 s.\n\nThis is joint work with Karthyek Murthy (SUTD).\n\nZoom link: https:
 //zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1107
DTSTART;TZID=Asia/Kolkata:20201218T171500
DTEND;TZID=Asia/Kolkata:20201218T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1108
DTSTAMP:20230914T125950Z
SUMMARY:Algebraic Natural Proofs: the plot thickens
DESCRIPTION:Speaker: Anamay Tengse\n\nAbstract: \nIn the late 1990s\, a pap
 er by Razborov and Rudich pointed out a barrier towards proving boolean ci
 rcuit lower bounds. They observed that almost all of the then known lower 
 bounds could be proved using a specific template: the 'natural proofs fram
 ework'. They further showed that any 'natural proof' for P/poly (poly-size
 d boolean circuits) would contradict the existence of One-Way-Functions: a
  crucial primitive in modern day cryptography. Thus\, their paper essentia
 lly ruled out "natural" techniques for proving strong boolean circuit lowe
 r bounds.\n\nAbout two decades later\, two groups: Grochow\, Kumar\, Saks 
 and Saraf (2017)\, and Forbes\, Shpilka and Volk (2018)\, independently pr
 oposed the framework of 'algebraically natural proofs' for algebraic circu
 its. They observed that most of the known lower bounds against algebraic c
 ircuit models fit in this framework\, and showed that 'algebraically natur
 al proofs' do not exist for VP (poly-sized algebraic circuits)\, under a (
 non-standard) derandomisation assumption. Forbes\, Shpilka and Volk (2018)
  also provided some evidence that suggested that the derandomisation assum
 ption might indeed be true.\n\nThis year\, in joint works with Chatterjee\
 , Kumar\, Ramya and Saptharishi\, we observed the following seemingly cont
 radictory facts about algebraically natural proofs.\n1. Algebraically natu
 ral proofs (kind of) *exist* for all "interesting" polynomials in VP and V
 NP (algebraic P and NP).\n2. Algebraically natural proofs *do not exist* f
 or VNP (algebraic NP)\, if permanent is exponentially hard.\nIn this talk\
 , we will first understand the algebraically natural proofs framework\, an
 d then try to make sense of our recent findings.\n\nZoom link: https://zoo
 m.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1108
DTSTART;TZID=Asia/Kolkata:20210101T171500
DTEND;TZID=Asia/Kolkata:20210101T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1109
DTSTAMP:20230914T125950Z
SUMMARY:Singularly Optimal Randomized Leader Election
DESCRIPTION:Speaker: William K. Moses Jr. (University of Houston\, USA)\n\n
 Abstract: \nThis paper concerns designing  distributed algorithms that ar
 e singularly optimal\, i.e.\, algorithms that are simultaneously time and 
 message optimal\, for the  fundamental leader election problem in network
 s. Our main result is a randomized distributed leader election algorithm f
 or asynchronous complete networks that is essentially (up to a polylogarit
 hmic factor) singularly optimal. Our algorithm uses O(n) messages with hig
 h probability and runs in O(\\log^2 n) time (with high probability) to ele
 ct a unique leader. The O(n) message complexity should be contrasted with 
 the \\Omega(n \\log n) lower bounds for the deterministic message complexi
 ty of leader election algorithms (regardless of time)\, proven by Korach\,
  Moran\, and Zaks (TCS\, 1989) for asynchronous algorithms and by Afek and
  Gafni (SIAM J. Comput.\, 1991) for synchronous networks. Hence\, our resu
 lt also separates the message complexities of randomized and deterministic
  leader election. More importantly\, our (randomized) time complexity of O
 (\\log^2 n) for obtaining the optimal O(n) message complexity is significa
 ntly smaller than the long-standing \\tilde{\\Theta}(n) time complexity ob
 tained by Afek and Gafni and by Singh (SIAM J. Comput.\, 1997)  for messa
 ge optimal (deterministic) election in asynchronous networks. Afek and Gaf
 ni also conjectured that \\tilde{\\Theta}(n) time would be optimal for mes
 sage-optimal asynchronous algorithms. Our result shows that randomized alg
 orithms are significantly faster.\nTurning to synchronous complete network
 s\, Afek and Gafni showed an essentially singularly optimal deterministic 
 algorithm with O(\\log n) time and O(n \\log n) messages. Ramanathan et al
 . (Distrib. Comput. 2007) used randomization to improve the message comple
 xity\, and showed a randomized algorithm with O(n) messages but still with
  O(\\log n) time (with failure probability O(1 / \\log^{\\Omega(1)}n)). Ou
 r second result shows that synchronous complete networks admit a tightly s
 ingularly optimal randomized algorithm\, with O(1) time and O(n) messages 
 (both bounds are optimal). Moreover\, our algorithm's time bound holds wit
 h certainty\, and its message bound holds with high probability\, i.e.\, 1
 -1/n^c for constant c.\nOur results demonstrate that leader election can b
 e solved in a simultaneously message and time-efficient manner in asynchro
 nous complete networks using randomization. It is open whether this is pos
 sible in asynchronous general networks.\nThis talk is based on joint work 
 with Shay Kutten\, Gopal Pandurangan\, and David Peleg which was published
  at DISC 2020.\nBio: William K. Moses Jr. is currently a postdoc at the U
 niversity of Houston in Houston\, USA\, where he is hosted by Gopal Pandur
 angan. Prior to that\, he was a postdoc at the Technion and received his P
 hD from IIT Madras in 2018. He is interested in the theory of distributed 
 computing with a focus on distributed algorithms. His three current areas 
 of focus are problems in general graphs\, programmable matter\, and mobile
  robots. He has in the past worked on problems related to SINR networks an
 d load balancing. His profile can be accessed here:  https://sites.google
 .com/view/wkmjr/home\nZoom link:\nhttps://zoom.us/j/98132227553?pwd=K2cyQl
 lKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1109
DTSTART;TZID=Asia/Kolkata:20210109T100000
DTEND;TZID=Asia/Kolkata:20210109T110000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1110
DTSTAMP:20230914T125950Z
SUMMARY:Hardness of Recognizing Geometric Intersection Graphs
DESCRIPTION:Speaker: Kshitij Gajjar (Technion - Israel Institute of Technol
 ogy\nHaifa\, Israel.)\n\nAbstract: \nMany graph problems that are NP-hard 
 for general graphs can be solved in polynomial time for planar graphs. We 
 explore the domain of "almost" planar graphs. These are graphs that can be
  made planar by removing one or two vertices from them. We show that recog
 nition of intersection graphs for several different types of geometric obj
 ects in the plane (e.g.\, line segments\, elliptical disks\, rectangles\, 
 simple curves\, etc.) is NP-hard\, even if the inputs are restricted to al
 most planar graphs.\n\nNo background other than high school geometry will 
 be assumed for this talk.\nThis is joint work with Dibyayan Chakraborty.\n
 \nZoom link:\nhttps://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcE
 t0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1110
DTSTART;TZID=Asia/Kolkata:20210115T171500
DTEND;TZID=Asia/Kolkata:20210115T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1111
DTSTAMP:20230914T125951Z
SUMMARY:Secure Multiparty Computation with Limited Connectivity
DESCRIPTION:Speaker: Varun Narayanan\n\nAbstract: \nInformation theoretical
 ly secure multiparty computation (MPC) is a central primitive in modern cr
 yptography.\nIt enables mutually distrusting parties to collaboratively pe
 rform computations on their combined data by ensuring that each party's da
 ta is kept private from the others.\nThis is achieved by designing communi
 cation protocols which allow the parties to collectively simulate an incor
 ruptible trusted party\, who privately receives inputs from the parties\, 
 computes the pre-agreed functionality\, and delivers the outputs to the ap
 propriate parties privately.\nThe subject of this dissertation is MPC when
  there is limited connectivity in the communication network available to t
 he participants.\nOur motivations and the progress we made in addressing t
 hem follows:\n- In many practical scenarios\, the parties may only have ac
 cess to a communication network with limited connectivity\, in that\, not 
 every pair of parties can communicate privately and reliably with each oth
 er.\nWe characterize the conditions under which a pair of parties can comp
 ute any functionality with information theoretic security in an incomplete
  network of reliable\, private links.\nSeparate characterizations are obta
 ined for honest-but-curious and malicious modes of corruption with securit
 y against general adversary structures.\n- Many cryptographic tasks can be
  modelled as secure 2-party computation (2PC) using only one-directional c
 ommunication.\nGarg et al. (Crypto 15) initiated the study of non-interact
 ive 2PC over noisy channels with one-way communication\, namely when only 
 one party speaks.\nA major question left open by that work was the complet
 eness of finite channels in this model of secure computation.\nWe show tha
 t bit-ROT (i.e.\, Randomized Oblivious Transfer) channel\, which erases on
 e of the two input bits uniformly at random\, can compute any functionalit
 y with inverse polynomial security error (in the number of channel uses) i
 n this model against a computationally unbounded adversary.\nFurther\, ass
 uming ideal obfuscation\, realizable using tamper-proof hardware tokens\, 
 naturally occurring channels such as binary symmetric channel (BSC) and bi
 nary erasure channel (BEC) are complete in this sense with inverse polynom
 ial security error against a computationally bounded adversary.\nTo comple
 ment this\, we show that no channel with finite alphabet is complete in th
 is model with negligible security error even against a computationally bou
 nded adversary.\nFinally\, we characterize the channels that enable zero-k
 nowledge proofs in this model\; the previous result work had presented con
 struction of zero-knowledge proofs using BEC/BSC channels.\n- Studying sec
 ure computation with limited interaction tends to reveal new frontiers to 
 approach the problem of complexity of several information theoretic primit
 ives: a notoriously hard problem in cryptography.\nWe introduce a new prim
 itive in information-theoretic cryptography\, namely zero-communication re
 ductions (ZCR)\, with varying levels of security\, and relate it with seve
 ral other important primitives.\nUsing these connections\, we obtain new u
 pper bounds and lower bounds for complexity of several cryptographic primi
 tives.\n- MPC provides a meaningful and robust definition of security that
  can be used for modelling security guarantees for existing models in netw
 ork information theory.\nIndex coding is a well studied problem\, in which
  a server wants to efficiently broadcast n messages intended for n users\,
  each with access to a subset of these messages as side information.\nWe i
 ntroduce a notion of privacy in index coding\, where the receivers do not 
 learn anything more than the message they want from the server and those t
 hey have as side information\, and study various aspects of its transmissi
 on rate and secret consumption rate.\n
URL:https://www.tcs.tifr.res.in/web/events/1111
DTSTART;TZID=Asia/Kolkata:20210118T110000
DTEND;TZID=Asia/Kolkata:20210118T120000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1112
DTSTAMP:20230914T125951Z
SUMMARY:Approximating a polynomial as a sum of simple polynomials
DESCRIPTION:Speaker: Neeraj Kayal (Microsoft Research)\n\nAbstract: \nIn th
 is talk\, we will consider algorithmic problems which follow the following
  template: given a real-valued multivariate polynomial f(x) of degree d\, 
 is it approximately equal to a sum of a few "simple" polynomials\, i.e Is 
 f ~= g_1(x) + g_2(x) + ... + g_r(x)? Examples/special cases of this proble
 m template are low-rank approximation of a matrix and tensor decomposition
 . We will see many applications including independent component analysis\,
  subspace clustering\, Learning Gaussian mixture models and (language) top
 ic modelling. In the next part\, we will see how techniques from algebraic
  complexity can potentially be used to algorithmically solve such problems
  efficiently. We will formulate some conjectures in this regard. We resolv
 e one such conjecture which leads to a more noise-resilient algorithm for 
 the relatively well-studied problem of tensor decomposition.\nYouTube Link
  - https://www.youtube.com/watch?v=ZCU74TXmG9o\n
URL:https://www.tcs.tifr.res.in/web/events/1112
DTSTART;TZID=Asia/Kolkata:20210126T160000
DTEND;TZID=Asia/Kolkata:20210126T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1113
DTSTAMP:20230914T125951Z
SUMMARY:An Introduction to Chordal  Graphs And Clique Trees
DESCRIPTION:Speaker: Vidya Sagar Sharma\n\nAbstract: \nAn undirected graph 
 is chordal if every cycle of length greater than three has a chord: namely
 \, an edge connecting two nonconsecutive vertices on the cycle.  A clique
  of a graph $G$ is any maximal set of vertices that is complete in $G$.  
 Let $G$ be a chordal graph and $K_G = \\{ K_1\, K_2\, ...\, K_m \\}$  den
 otes the set containing the cliques of $G$\, then a tree with vertex set $
 K_G$ is said to be a clique tree of the chordal graph $G$ if it follows th
 e clique intersection property: For every pair of distinct cliques $K\,K' 
 \\in K_G$\, the set $K \\cap K'$ is contained in every clique on the path 
 connecting $K$ and $K'$ in the tree.\n\nIn this talk\, we will see a few p
 roperties of the chordal graphs and the clique trees of the chordal graphs
 .\nReference: link.springer.com/content/pdf/10.1007%2F978-1-4613-8369-7_1.
 pdf\n\nZoom Link : https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc
 0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1113
DTSTART;TZID=Asia/Kolkata:20210130T171500
DTEND;TZID=Asia/Kolkata:20210130T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1114
DTSTAMP:20230914T125951Z
SUMMARY:Differential Games in Spread of Diseases.
DESCRIPTION:Speaker: Sushant Vijayan\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1114
DTSTART;TZID=Asia/Kolkata:20210205T093000
DTEND;TZID=Asia/Kolkata:20210205T103000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1115
DTSTAMP:20230914T125951Z
SUMMARY:An Exploration of R ́enyi Divergence Based Upper Bounds on General
 ization Error
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1115
DTSTART;TZID=Asia/Kolkata:20210205T103000
DTEND;TZID=Asia/Kolkata:20210205T113000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1116
DTSTAMP:20230914T125951Z
SUMMARY:Paper: Pseudorandom Generators from Polarizing Random Walks by Esha
 n Chattopadhyay\, Pooya Hatami\, Kaave Hosseini\, and Shachar Lovett
DESCRIPTION:Speaker: Ashutosh Shankar\n\nAbstract: \nhttps://theoryofcomput
 ing.org/articles/v015a010/\n
URL:https://www.tcs.tifr.res.in/web/events/1116
DTSTART;TZID=Asia/Kolkata:20210205T113000
DTEND;TZID=Asia/Kolkata:20210205T123000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1117
DTSTAMP:20230914T125951Z
SUMMARY:Element distinctness using arbitrary binary gates
DESCRIPTION:Speaker: Siddharth Bhandari\n\nAbstract: \nWe will study the De
 cision-Tree complexity of element distinctness using arbitrary binary gate
 s (an instance of which is comparison gates). Concretely\, let $m$ and $n$
  be natural numbers with $m>n$. Suppose\, we are given an array $A[1]\,A[2
 ]\,\\ldots\,A[n]$ where each $A[i]\\in [m]$. At each step we are allowed t
 o pick two indices $i$ and $j$ in $[n]$ and an arbitrary function $f:\\N \
 \times \\N \\to \\{0\,1\\}$\, and ask for the value of $f(A[i]\,A[j])$. At
  the end of the procedure we must be able to tell whether all the entries 
 of $A$ were distinct or not. Define by $S(m\,n)$ the minimum number of ste
 ps needed in such a procedure. We are interested in understanding the asym
 ptotics of $S(m\,n)$.\nIn the specific case when we are restricted to use 
 only comparison gates\, i.e.\, $f(a\,b)=[a>b]$ we will see that $S(m\,n)=\
 \Theta(n \\log n)$ for all $m\\geq n$.\nIn the more general setting where 
 we are allowed to use arbitrary gates\, we will see that when $m>>n$ then 
 $S(m\,n)=\\Theta(n \\log n)$. However\, when $m=n$ our understanding is in
 complete: $S(m\,n)=\\Omega(n \\sqrt(\\log n))$. (This is a result of Ravi 
 Boppana https://www.sciencedirect.com/science/article/pii/0020019094001545
 ?via%3Dihub). If time permits we might discuss a few ideas to bridge this 
 gap.\nZoom link:\nhttps://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0
 ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1117
DTSTART;TZID=Asia/Kolkata:20210212T171500
DTEND;TZID=Asia/Kolkata:20210212T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1118
DTSTAMP:20230914T125951Z
SUMMARY:Banach-Tarski Paradox
DESCRIPTION:Speaker: Abhishek Khetan\n\nAbstract: \nIn this talk we will gi
 ve a proof of the fact that the two dimensional sphere can be partitioned 
 into finitely many pieces in such a way that a rearrangement of the pieces
  produces two disjoint copies of the original sphere.\nZoom link:\nhttps:/
 /zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1118
DTSTART;TZID=Asia/Kolkata:20210219T171500
DTEND;TZID=Asia/Kolkata:20210219T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1119
DTSTAMP:20230914T125951Z
SUMMARY:Existence of Strategy in Games
DESCRIPTION:Speaker: Prabhat Kumar Jha\n\nAbstract: \nGames are used to mod
 el many instances arising from interaction of more than one computational 
 agent. In program synthesis\, existence of strategy is the key in deciding
  the existence of a program with a given set of specifications.\n\nIn this
  talk\, we will observe Martin's proof of the existence of strategy in a c
 lass of two-player infinite games with perfect information (namely Borel g
 ames). One instance of this result is that in the initial stage of a game 
 of chess\, at least one of the players has a strategy to prevent from losi
 ng.\n\nLink of the paper: https://www.jstor.org/stable/pdf/1971035.pdf?ref
 reqid=excelsior%3Aed93a87cd71602b5a789b6280bf1a5a6\n
URL:https://www.tcs.tifr.res.in/web/events/1119
DTSTART;TZID=Asia/Kolkata:20210226T150000
DTEND;TZID=Asia/Kolkata:20210226T160000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1120
DTSTAMP:20230914T125951Z
SUMMARY:Tensor Rank and Algebraic Formula Lower Bounds
DESCRIPTION:Speaker: Prerona  Chatterjee\n\nAbstract: \nTensor are higher d
 imensional analogues of matrices and there is a notion of the rank of a te
 nsor (similar to matrices). However\, unlike matrices\, finding the rank o
 f a tensor is NP-hard and it is a big open problem to find explicit tensor
  of large rank. Raz showed that in certain regimes\, finding such an expli
 cit tensor would yield lower bounds against algebraic formulas (a natural 
 model for computing polynomials). In this talk\, we will introduce tensors
  and view them as some structured polynomials. We will then go over the pr
 oof idea of the statement mentioned above and completely prove one of the 
 main structural lemmas used. The talk is based on the presentation of Raz'
 s paper (https://dl.acm.org/doi/10.1145/2535928) as given in chapter 16 of
  Ramprasad's survey (https://github.com/dasarpmar/lowerbounds-survey/relea
 ses/download/v8.0.7/fancymain.pdf). Zoom link: https://zoom.us/j/981322275
 53?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1120
DTSTART;TZID=Asia/Kolkata:20210312T171500
DTEND;TZID=Asia/Kolkata:20210312T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1121
DTSTAMP:20230914T125951Z
SUMMARY:STCS Annual Symposium
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1121
DTSTART;TZID=Asia/Kolkata:20210319T090000
DTEND;TZID=Asia/Kolkata:20210320T180000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1122
DTSTAMP:20230914T125951Z
SUMMARY:Chasing Convex Functions
DESCRIPTION:Speaker: Anupam Gupta (Carnegie Mellon University)\n\nAbstract:
  \nThe problem of chasing convex functions is easy to state: faced with a 
 sequence of convex functions {f_t}\, the goal of the algorithm is to outpu
 t a point x_t at each time\, so that the sum of the function costs f_t(x_t
 )\, plus the movement costs || x_t - x_{t-1} || is minimized. This general
  problem generalizes several classic questions in online algorithms\, such
  as caching and the k-server problem.\nThe question of getting an algorith
 m whose total cost is comparable to the optimal cost in hindsight was pose
 d by Friedman and Linial in 1994. This was finally (mostly) resolved last 
 year\, using a combination of ideas from online algorithms and convex geom
 etry. In this talk we will survey the results and ideas.\nThis is based on
  works with C.J.Argue\, S.Bubeck\, M.B.Cohen\, G.Guruganesh\, Y. T.Lee\, a
 nd Z.Tang.\nYouTube link : https://www.youtube.com/watch?v=TMilw8CX1Yg\n
URL:https://www.tcs.tifr.res.in/web/events/1122
DTSTART;TZID=Asia/Kolkata:20210323T160000
DTEND;TZID=Asia/Kolkata:20210323T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1123
DTSTAMP:20230914T125951Z
SUMMARY:Generalization and Guessing
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nAbstract: Generalization e
 rror is the gap between an algorithm's performance on the true data distri
 bution (unknown to us) and its performance on the given dataset (known to 
 us). Thus\, establishing upper bounds on generalization error is naturally
  of interest. In 2020\, Steinke and Zakynthinou derived their bound in ter
 ms of the ability to guess an algorithm's input by observing its output. I
 n this talk\, we will try to go over the proof of this result.\nLink to th
 e paper: https://arxiv.org/abs/2001.09122\n\nZoom link:\nhttps://zoom.us/j
 /98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1123
DTSTART;TZID=Asia/Kolkata:20210326T171500
DTEND;TZID=Asia/Kolkata:20210326T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1124
DTSTAMP:20230914T125951Z
SUMMARY:Two-and-a-half proofs of "the duality trick"
DESCRIPTION:Speaker: Anamay Tengse\n\nAbstract: \nThe fact that the polynom
 ial (x1+...+xn)^d can be written as a poly(n\,d)-sum of products of univar
 iates is a consequence of what is popularly known as 'the duality trick' i
 n the algebraic complexity circles. The actual identity is much more gener
 al\, and in particular\, applies to any linear form raised to an arbitrary
  power. Saxena (2008) famously used this duality to derive identity testin
 g algorithms for polynomials that are poly(n\,d)-sums of powers of linear 
 forms. This model (AKA sum-power-sum) coincides with the well-studied noti
 on of Waring rank in mathematics.\n\nIn this talk\, we will see two proofs
  of the duality trick due to Saxena and Shpilka respectively. Both these p
 roofs use fairly elementary ideas about polynomials. We shall then see a d
 ifferent proof of correctness of Saxena's construction that uses mildly no
 n-elementary algebraic geometry.\n\nZoom link: https://zoom.us/j/981322275
 53?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1124
DTSTART;TZID=Asia/Kolkata:20210409T171500
DTEND;TZID=Asia/Kolkata:20210409T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1125
DTSTAMP:20230914T125951Z
SUMMARY:Network Coding Conjecture implies Data Structure Lower Bounds
DESCRIPTION:Speaker: Pavel Dvorak (Charles University\, Prague)\n\nAbstract
 : \nNetwork coding conjecture (NCC) by Li and Li asserts that network codi
 ng for undirected graphs does not bring any advantage over multicommodity 
 flows. Recently\, NCC was used to prove a conditional lower bound for sort
 ing algorithms with external memory [Farhadi et al.\, STOC 2019]\, circuit
 s for multiplication [Afshani et al.\, ICALP 2019]\, and circuits for sort
 ing [Asharov et al.\, SODA 2021]. We use a technique of Farhadi et al. to 
 prove an NCC-based lower bound for non-adaptive data structures for functi
 on inversion\, polynomial evaluation\, and polynomial interpolation. This 
 is a joint work with Michal Koucký\, Karel Král and Veronika Slívová.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1125
DTSTART;TZID=Asia/Kolkata:20210415T174500
DTEND;TZID=Asia/Kolkata:20210415T184500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1126
DTSTAMP:20230914T125951Z
SUMMARY:Fair Cake Division
DESCRIPTION:Speaker: Nidhi Rathi (IISc Bangalore)\n\nAbstract: \nThe theory
  of Fair Division addresses the fundamental problem of allocating goods am
 ong agents with equal entitlements but distinct preferences. The classic c
 ake-cutting problem provides a model for addressing fair and efficient all
 ocation of a divisible\, heterogeneous resource (metaphorically\, the cake
 ) among agents with varied preferences. Classic results of Stromquist (198
 0) and Su (1999) show that envy-free (fair) cake divisions (with contiguou
 s pieces) are guaranteed to exist under mild conditions. These strong exis
 tential results follow from fixed-point theorems and stand without an algo
 rithmic counterpart.\n\nIn this talk\, I will present two of the recent re
 sults that complements the existential (and non-constructive) guarantees a
 nd various hardness results either by developing polynomial-time approxima
 tion algorithms or by identifying computationally tractable instances for 
 fair cake division. Our work identifies a broad class of cake division ins
 tances that essentially admits a polynomial time algorithm for computing f
 air and efficient allocations. In particular\, our algorithmic result hold
 s when (all) agents' valuations are induced either by linear translations 
 of any log-concave function\, Gaussian\, exponential\, linear\, or binomia
 l distributions.\n\nJoint work with Siddharth Barman\, Eshwar Ram Arunchal
 eswaran and Rachitesh Kumar.\n\nhttps://arxiv.org/abs/2006.00481\nhttps://
 arxiv.org/abs/1907.11019\n\nZoom link: https://zoom.us/j/98132227553?pwd=K
 2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1126
DTSTART;TZID=Asia/Kolkata:20210416T171500
DTEND;TZID=Asia/Kolkata:20210416T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1127
DTSTAMP:20230914T125951Z
SUMMARY:Singly Connected Vertex Deletion Problem
DESCRIPTION:Speaker: Avinandan Das (Institut de Recherche en Informatique F
 ondamentale\, Paris)\n\nAbstract: \nIn this talk\, I am going to present t
 he Singly Connected Vertex Deletion Problem (SCVD).\nA digraph D is singly
  connected if for all ordered pairs of vertices u\, v ∈ V (D)\, there is
  at most one path in D from u to v. In this paper\, we study the Singly Co
 nnected Vertex Deletion (SCVD) problem: Given an n-vertex digraph D and a 
 positive integer k\, does there exist a set S ⊆ V (D) such that |S| ≤ 
 k and D − S is singly connected? This problem may be seen as a directed 
 counterpart of the (Undirected) Feedback Vertex Set problem\, as an undire
 cted graph is singly connected if and only if it is acyclic. SCVD is known
  to be NP-hard on general digraphs. We study the complexity of SCVD on var
 ious classes of digraphs such as tournaments\, and various generalisations
  of tournaments such as digraphs of bounded independence number\, in- and 
 out-tournaments and local tournaments. We show that unlike the Feedback Ve
 rtex Set on Tournaments (FVST) problem\, SCVD is polynomial-time solvable 
 on tournaments. In addition\, we show that SCVD is polynomial-time solvabl
 e on digraphs of bounded independence number\, and on the class of acyclic
  local tournaments. We also study the parameterized complexity of SCVD\, w
 ith k as the parameter\, on the class of in-tournaments. And we show that 
 on in-tournaments\, SCVD admits a fixed-parameter tractable algorithm and 
 a quadratic kernel.\n\nWe also show that on the class of local tournaments
 \, which is a sub-class of in-tournaments\, SCVD admits a linear kernel.\n
 \nZoom link: https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt
 0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1127
DTSTART;TZID=Asia/Kolkata:20210423T171500
DTEND;TZID=Asia/Kolkata:20210423T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1128
DTSTAMP:20230914T125951Z
SUMMARY:A Tale of Turing Machines\, Quantum-Entangled Particles\, and Opera
 tor Algebras
DESCRIPTION:Speaker: Henry Yuen (University of Toronto)\n\nAbstract: \nBelo
 w event would be a screening of a past talk by Henry Yuen (available on Yo
 uTube) with the same title.\n\nIn a recent result known as "MIP* = RE\," i
 deas from three disparate fields of study — computational complexity the
 ory\, quantum information\, and operator algebras — have come together t
 o simultaneously resolve long-standing open problems in each field\, inclu
 ding a 44-year old mystery in mathematics known as Connes’ Embedding Pro
 blem. In this talk\, I will describe the evolution and convergence of idea
 s behind MIP* = RE: it starts with three landmark discoveries from the 193
 0s (Turing’s notion of a universal computing machine\, the phenomenon of
  quantum entanglement\, and von Neumann’s theory of operators)\, and end
 s with some of the most cutting-edge developments from theoretical compute
 r science and quantum computing.\n\nThis talk is aimed at a general scient
 ific audience\, and will not assume any specialized background in complexi
 ty theory\, quantum physics\, or operator algebras.\n\nZoom link:  https:/
 /zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1128
DTSTART;TZID=Asia/Kolkata:20210430T171500
DTEND;TZID=Asia/Kolkata:20210430T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1129
DTSTAMP:20230914T125951Z
SUMMARY:Eluder dimension and sample complexity of Optimistic exploration
DESCRIPTION:Speaker: Sushant Vijayan\n\nAbstract: \nI will present the 2013
  NIPS paper by Dan Russo and Van Roy where they introduce the notion of El
 uder dimension and use it to analyse the UCB and Thompson Sampling algorit
 hms.\n\nZoom link: https://zoom.us/j/98132227553?pwd=K2cyQllKVjExdUhlRm0vc
 0ZHcEt0Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1129
DTSTART;TZID=Asia/Kolkata:20210507T171500
DTEND;TZID=Asia/Kolkata:20210507T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1130
DTSTAMP:20230914T125951Z
SUMMARY:Communication Complexity and Quantum Optimization Lower Bounds via 
 Query Complexity
DESCRIPTION:Speaker: Suhail Sherif\n\nAbstract: \nThe query model is a simp
 le model of computation that has led to many deep results. One such class 
 of results relates computational complexity measures such as query complex
 ity/communication complexity to algebraic measures such as degree/rank. Th
 e first part of this thesis deals with such relations. The results of this
  part of the thesis are given below.\n\n1. In the context of randomized co
 mmunication complexity and randomized parity decision tree (RPDT) complexi
 ty\, we prove that the relevant computational measures and algebraic measu
 res are not closely related. This disproves multiple long-standing conject
 ures in communication complexity.\n\n2. We try to quantitatively strengthe
 n the above result. We do manage to do so in the context of RPDTs\, but th
 ere are challenges in translating this strengthening to the context of ran
 domized communication complexity. We pose a fundamental conjecture that wo
 uld imply that the strengthening holds in the communication world as well.
 \n\nIn the second part of the thesis\, we look at convex optimization. The
  goal is to optimize a convex function in a bounded region when you can on
 ly learn about the function through function value and gradient queries. W
 e want to use as few queries as possible. Projected gradient descent (PGD)
  is a well-known algorithm that optimally solves this task when the dimens
 ion of the function's domain is large. In the second part of the thesis we
  add to the optimality results of PGD.\n\n3. (a) In the case of quantum al
 gorithms it was open whether there is a quadratic speedup over PGD when th
 e dimension is large. We show that this is not so\, that PGD is optimal up
  to constant factors.\n(b) In the case of randomized algorithms we show a 
 simple argument bettering the range of dimensions where PGD is known to be
  optimal up to constant factors.\n\nWe end with a few open problems.\n\nJo
 in Zoom Meeting\nhttps://zoom.us/j/93580606744?pwd=L1pCek1pSy91a0JOOXpXdjI
 0Z2EyQT09\nMeeting ID: 935 8060 6744\nPasscode: 335095\n
URL:https://www.tcs.tifr.res.in/web/events/1130
DTSTART;TZID=Asia/Kolkata:20210517T170000
DTEND;TZID=Asia/Kolkata:20210517T180000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1131
DTSTAMP:20230914T125951Z
SUMMARY:Colloquia on the 2021 Abel Prize in Mathematics
DESCRIPTION:Speaker: Prof. Arkadev Chattopadhayay (TIFR)\, Prof. Prahladh H
 arsha (TIFR)\, Prof. Mahan Maharaj (TIFR)\, Prof. Hariharan Narayanan (TIF
 R)\, Prof. Jaikumar Radhakrishnan (TIFR) (School of Technology and Compute
 r Science\,\nTIFR\, Mumbai.)\n\nAbstract: \nCovering Contributions of Abel
  Laureate Avi Wigderson\n\nArkadev Chattopadhyay "Games Avi Plays To Prove
  Hardness"\n\nPrahlad Harsha "How Avi copes with Difficulty: A computation
 al perspective on randomness and knowledge"\n\nCovering Contributions of A
 bel Laureate László Lovász\n\nMahan Maharaj "Graph limits"\n\nHariharan
  Narayanan "Volume Computation for Convex bodies"\n\nJaikumar Radhakrishna
 n "The Lovasz Local Lemma"\n\nAt Online through ZOOM webinar ( Zoom link: 
 https://zoom.us/j/97963259354?pwd=ZFZsa2xqWGJSZW5pUjZPNkNqeGlEZz09 )\nMeet
 ing ID: 979 6325 9354 Pass code: 04072020\n
URL:https://www.tcs.tifr.res.in/web/events/1131
DTSTART;TZID=Asia/Kolkata:20210519T160000
DTEND;TZID=Asia/Kolkata:20210519T173000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1132
DTSTAMP:20230914T125951Z
SUMMARY:Hitting Sets for Orbits of Circuit Classes
DESCRIPTION:Speaker: Vishwas Bhargava (Ph.D. student at Rutgers)\n\nAbstrac
 t: \nThe \\emph{orbit} of an n-variate polynomial f(\\var x) over a field 
 \\F\, denoted by \\orbit{f}\, is the set of polynomials obtained by applyi
 ng invertible affine transformations on the variables of f(\\var x)\, and 
 the orbit of a polynomial class is the union of orbits of all the polynomi
 als in it.\n\nIn this talk\, we will discuss recent progress on designing 
 hitting sets for orbits of various circuit classes. In particular\, we wil
 l discuss improved construction of hitting-sets for the orbit of read-once
  oblivious algebraic branching programs (ROABPs).\n\nJoint work with Sumat
 a Ghosh (IIT-B).\n\nZoom link:\nhttps://zoom.us/j/93889521556?pwd=eEFJWVRt
 RHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1132
DTSTART;TZID=Asia/Kolkata:20210528T171500
DTEND;TZID=Asia/Kolkata:20210528T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1133
DTSTAMP:20230914T125951Z
SUMMARY:Communication with Adversary Identification in Byzantine Multiple A
 ccess channels
DESCRIPTION:Speaker: Neha Sangwan\n\nAbstract: \nIn this talk\, I will intr
 oduce the problem of determining the identity of a byzantine user (interna
 l adversary) in a communication system. We will consider a two-user discre
 te memoryless multiple access channel where either user may deviate from t
 he prescribed behaviour. Owing to the noisy nature of the channel\, it may
  be overly restrictive to attempt to detect all deviations. In our formula
 tion\, we only require detecting deviations which impede the decoding of t
 he non-deviating user's message. When neither user deviates\, correct deco
 ding is required. When one user deviates\, the decoder must either output 
 a pair of messages of which the message of the non-deviating user is corre
 ct or identify the deviating user. The users and the receiver do not share
  any randomness. The results include a characterization of the set of chan
 nels where communication is feasible\, and an inner and outer bound on the
 \ncapacity region.\nThe talk should be easy to follow for everyone\, inclu
 ding the first years.\nZoom link:\nhttps://zoom.us/j/93889521556?pwd=eEFJW
 VRtRHNpNlpZWmhNYTJGQTF6Zz09\n \n
URL:https://www.tcs.tifr.res.in/web/events/1133
DTSTART;TZID=Asia/Kolkata:20210604T171500
DTEND;TZID=Asia/Kolkata:20210604T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1134
DTSTAMP:20230914T125951Z
SUMMARY:Hitting Sets for Algebraic Models: Constructions and Consequences
DESCRIPTION:Speaker: Anamay Tengse\n\nAbstract: \nWe study hitting sets for
  polynomials computed by several algebraic models. For a class of polynomi
 als C\, hitting sets for C capture the problem of deterministic blackbox P
 IT for C: checking if a polynomial f from C is zero by querying f on a few
  points. Formally\, H is a hitting set for a class C\, if for every nonzer
 o f in C\, there is some point h in H for which f(h) is nonzero. Owing to 
 its close connections to the search of explicit hard polynomials\, finding
  small\, explicit hitting sets for various classes of polynomials is a cen
 tral question in algebraic complexity theory.\n\nOur contributions towards
  the study of hitting sets are as follows. We provide two explicit constru
 ctions of hitting sets: quasipolynomial sized hitting sets for 'UPT circui
 ts'\, and poly-sized hitting sets for log-variate 'depth-3-powering circui
 ts'. Next\, we show that for any general enough algebraic model\, like cir
 cuits or formulas\, even a mild improvement to the trivial hitting sets fo
 r the model leads to almost efficient\, explicit hitting sets for that mod
 el. Lastly\, we explore how non-trivial hitting sets for a class of polyno
 mials help us in proving lower bounds against that class.\n\nThe talk will
  be based on my joint works with Prerona Chatterjee (TIFR)\, Mrinal Kumar 
 (IITB)\, C. Ramya (TIFR) and Ramprasad Saptharishi (TIFR).\n\nZoom link: h
 ttps://zoom.us/j/92326426336?pwd=V2h0WGpUeklMd01Mak1sVGpvTm9QUT09\n
URL:https://www.tcs.tifr.res.in/web/events/1134
DTSTART;TZID=Asia/Kolkata:20210609T143000
DTEND;TZID=Asia/Kolkata:20210609T153000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1135
DTSTAMP:20230914T125951Z
SUMMARY:Arithmetic Circuit Complexity of Division and Truncation
DESCRIPTION:Speaker: Gorav Jindal (TU Berlin\, Germany.)\n\nAbstract: \nGiv
 en n-variate polynomials f\,g\,h such that f=g/h\, where both g and h are 
 computable by arithmetic circuits of size s\, we show that f can be comput
 ed by a circuit of size poly(s\, deg(h)). This solves a special case of di
 vision elimination for high-degree circuits (Kaltofen'87 & WACT'16). This 
 result is an exponential improvement over Strassen's classic result (Stras
 sen'73) when deg(h) is poly(s) and deg(f) is exp(s)\, since the latter giv
 es an upper bound of poly(s\, deg(f)).\nThe second part of this work deals
  with the complexity of computing the truncations of uni-variate polynomia
 ls or power series. We first show that the truncations of rational functio
 ns are easy to compute.  We also prove that the truncations of even very 
 simple algebraic functions are hard to compute\, unless integer factoring 
 is easy.\nThis is a joint work with Pranjal Dutta\, Anurag Pandey and Amit
  Sinhababu. A pre-print can be found at https://eccc.weizmann.ac.il/report
 /2021/072/ .\nZoom Link: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlp
 ZWmhNYTJGQTF6Zz09\n \n
URL:https://www.tcs.tifr.res.in/web/events/1135
DTSTART;TZID=Asia/Kolkata:20210611T171500
DTEND;TZID=Asia/Kolkata:20210611T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1136
DTSTAMP:20230914T125952Z
SUMMARY:Approximate Polymorphisms
DESCRIPTION:Speaker: Nitin Saurabh (Technion-IIT\, Haifa\, Israel)\n\nAbstr
 act: \nA Boolean function f on n variables is called a polymorphism of ano
 ther Boolean function g on m variables if their operations commute. That i
 s\, for all {0\,1}-matrix Z of dimension (n x m)\, f(g(row1(Z))\, g(row2(Z
 ))\, ...\, g(rown(Z))) = g(f(col1(Z))\, f(col2(Z))\, ...\,f(colm(Z))). The
  function f is called an approximate polymorphism if this equality holds w
 ith probability close to 1 when Z is sampled uniformly.\nThe problem of ch
 aracterizing the structure of exact or approximate polymorphisms appears i
 n several different contexts\, namely in understanding the complexity of C
 SPs\, property testing\, and social choice theory.\nIn this talk\, we will
  give a characterization of exact polymorphisms\, and also show that appro
 ximate polymorphisms must be close to exact polymorphisms. Our results gen
 eralize the classical linearity testing result of Blum et al. as well as t
 he recent AND testing result of Filmus et al.\nThis is based on a joint wo
 rk with Gilad Chase\, Yuval Filmus and Dor Minzer.\nZoom link: https://zoo
 m.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1136
DTSTART;TZID=Asia/Kolkata:20210618T171500
DTEND;TZID=Asia/Kolkata:20210618T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1137
DTSTAMP:20230914T125952Z
SUMMARY:Machine Learning: What is it and Why should we care?
DESCRIPTION:Speaker: Preethi Jyothi (Indian Institute of Technology Bombay\
 nMumbai\, Maharashtra.)\n\nAbstract: \nArtificial Intelligence\, specifica
 lly machine learning (ML)\, has increasingly been making inroads into soci
 ety and our lives over the last decade. We are entering an era where users
  are likely to take advantage of ML-driven technologies in all walks of li
 fe\, by interacting seamlessly with digital systems. But\, what is machine
  learning? What are the main milestones achieved in the last decade? What 
 are the challenges involved with building machine learning systems? I will
  aim to throw some light on these questions and also describe how ML shape
 s my research on speech and language.\nYoutube link: https://youtu.be/OGKW
 DcJNF7w\n
URL:https://www.tcs.tifr.res.in/web/events/1137
DTSTART;TZID=Asia/Kolkata:20210622T180000
DTEND;TZID=Asia/Kolkata:20210622T190000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1138
DTSTAMP:20230914T125952Z
SUMMARY:Great Ideas in Coding Theory: From Theory to Practice
DESCRIPTION:Speaker: Lalitha Vadlamani (International Institute of Informat
 ion Technology Hyderabad\nHyderabad\, Telangana.)\n\nAbstract: \nIn 1948\,
  Claude Shannon wrote his landmark paper on "A mathematical theory of comm
 unication"\, which paved way to the field of information theory. He introd
 uced the term entropy to measure information and also determined the funda
 mental limits of source compression and communication over a noisy channel
  (known as channel capacity). In his work\, he proved the existence of cod
 es which achieve the channel capacity. In 1950\, Richard Hamming discovere
 d the first-ever error correcting code which is single-error correcting. C
 oding theorists have contributed to designing codes which achieve the chan
 nel capacity in the decades to come. Low density parity check (LDPC) codes
  invented by Gallager in 1960s and rediscovered in 1990s proved to be very
  effective codes due to their low decoding complexity requirements at larg
 e block lengths. In 2009\, Erdal Arikan proposed polar codes which are the
  first class of codes provably capacity achieving for a class of binary in
 put discrete memoryless channels. There are several applications of coding
  theory\, apart from channel coding\, including storage devices\, distribu
 ted storage systems etc. Reed-Solomon and BCH codes have been conventional
 ly used in storage devices. More recently in 2012\, locally repairable cod
 es (LRC) were introduced by researchers in Microsoft to solve the repair p
 roblem in distributed storage systems.\nYoutube link: https://youtu.be/_Jp
 MoMdX7W4\n
URL:https://www.tcs.tifr.res.in/web/events/1138
DTSTART;TZID=Asia/Kolkata:20210624T180000
DTEND;TZID=Asia/Kolkata:20210624T190000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1139
DTSTAMP:20230914T125952Z
SUMMARY:Leveraging the Invariance Principle for Out-of-Distribution General
 ization
DESCRIPTION:Speaker: Karthikeyan Shanmugan (IBM Research AI\nT.J. Watson Ce
 nter\, NY.)\n\nAbstract: \nOne of the fundamental issues facing deployment
  of supervised learning models in real life applications is the issue of o
 ut-of-distribution (OOD) generalization. Models trained using the standard
  Empirical Risk Minimization (ERM) on multiple training data sources suffe
 r from fitting to spurious features that correlate with label which does n
 ot hold in unseen test environments. ERM’s sole focus on optimizing aver
 age risk contributes to this problem. Invariance Principle\, in Pearlian C
 ausal Models\, has long been used to infer causal relationships from inter
 ventional data.\nInvariant Risk Minimization (IRM) is a recent paradigm th
 at proposes to leverage the invariance principle in an optimization framew
 ork for OOD problems. This paradigm views different training distributions
  and the unseen test as intervened versions of a common but unknown causal
  model. IRM seeks to identify that transformation of data such that the cl
 assifier trained on top of it is invariant across training domains apart f
 rom optimizing risk. Due to a challenging bilevel optimization\, a previou
 s proposal was limited to handling linear classifiers. We propose a novel 
 game theoretic learning paradigm – called Ensemble Invariant Risk Minimi
 zation (EIRM Game) whose Nash Equilibria is provably equivalent to invaria
 nt solutions for a very general class of non-linear classifiers and transf
 ormations. For least squares regression under unobserved confounding\, wit
 h a modified game we provide the first convergence guarantees\, known for 
 this problem in any setting\, to approximate invariant solutions (this par
 t may be discussed if time permits).\n\nBio: Karthikeyan Shanmugam is a Re
 search Staff Member with the IBM Research AI group in NY in the Trustworth
 y AI Department since 2017. Previously\, he was a Herman Goldstine Postdoc
 toral Fellow in the Mathematical Sciences Division at IBM Research\, NY. H
 e obtained his Ph.D. in Electrical and Computer Engineering from UT Austin
  in 2016\, MS degree in Electrical Engineering from USC in 2012 and B.Tech
 \, M.Tech degrees in Electrical Engineering from IIT Madras in 2010.\nHis 
 research interests broadly lie in Statistical Machine Learning (ML)\, Opti
 mization\, Graph Algorithms\, and Information Theory. In ML\, his focus is
  on causal inference\, online learning\, transfer learning and explainable
  ML. He has won several awards in IBM for his contributions to explainable
  AI and Causal Inference including the Corporate Technical Award in 2021\,
  the highest technical award in IBM. His works have appeared regularly in 
 top AI/ML venues like NeurIPS\, ICML\, AISTATS and ICLR.\n
URL:https://www.tcs.tifr.res.in/web/events/1139
DTSTART;TZID=Asia/Kolkata:20210628T090000
DTEND;TZID=Asia/Kolkata:20210628T100000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1140
DTSTAMP:20230914T125952Z
SUMMARY:Cryptography: The Jugalbandi (duet) of Structure and Randomness
DESCRIPTION:Speaker: Shweta Agrawal (Indian Institute of Technology Madras\
 nChennai\, Tamil Nadu.)\n\nAbstract: \nCryptography is a beautiful branch 
 of theoretical computer science that seeks to provide guarantees to the ar
 t of secret keeping. The questions it poses are fundamental --  does the 
 universe permit asymmetry of computation? It's practical utility requires 
 no argument -- ad-hoc security solutions repeatedly fall prey to attack an
 d crime is increasingly digital. Its scientific charm lies in its deeply p
 aradoxical nature – among its early successes is the ability for two str
 angers to meet\, generate a secret key and communicate privately\, all of 
 these from within a crowd!\nIn this talk\, we will take a closer look at t
 his fascinating field\, paying special attention to the many apparent para
 doxes it enables. Via examples such as zero knowledge proofs\, fully homom
 orphic encryption and deniable encryption\, I hope to show you how it is t
 he perennial jugalbandi\, or duet between structure and randomness that en
 ables these beautiful and useful constructs.\nYoutube link: https://youtu.
 be/9sQRZAdrp3c\n
URL:https://www.tcs.tifr.res.in/web/events/1140
DTSTART;TZID=Asia/Kolkata:20210629T180000
DTEND;TZID=Asia/Kolkata:20210629T190000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1141
DTSTAMP:20230914T125952Z
SUMMARY:Vertex connectivity of Eulerian orientations
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nA directed graph is said t
 o be k-vertex-connected if after deleting any k-1 vertices\, therer is a d
 irected path from every vertex to every other vertex along the directed ed
 ges. An Eulerian orientation of a graph is an orientation such that every 
 vertex has equal indegree and outdegree. Given an 2k-regular graph G\, we 
 would like to know if every Eulerian orientation of G is k-vertex connecte
 d. Horsch and Szigeti showed that this property holds for complete biparti
 te graphs\, line graphs of regular complete bipartite graphs\, incidence g
 raphs of projective planes\, but not for most complete graphs. In this tal
 k\, we will go through their proofs. We will also show that this property 
 does not hold for most regular complete multipartite graphs. Link to paper
 : https://doi.org/10.1016/j.dam.2020.09.022. Zoom link is: https://zoom.us
 /j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1141
DTSTART;TZID=Asia/Kolkata:20210709T150000
DTEND;TZID=Asia/Kolkata:20210709T160000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1142
DTSTAMP:20230914T125952Z
SUMMARY:Fooling Boolean functions with expander random walks
DESCRIPTION:Speaker: Ashutosh Shankar\n\nAbstract: \nExpander graphs are sp
 arse but highly connected graphs\, which find a variety of uses in CS. If 
 the vertices of an expander are labelled by 0 or 1\, a $t$-step walk gives
  a $t$-bit string. Cohen\, Peri and Ta-Shma (2020) consider the question: 
 can a Boolean function on $t$ variables distinguish between a truly random
  $t$-bit string and a $t$-step walk in a labelled expander? We will see th
 at Majority and other symmetric functions can indeed be fooled by a walk. 
 However\, the "fooling" does not seem to improve with $t$\; we will see a 
 counterexample from a subsequent paper if time allows.\n\nZoom link : http
 s://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1142
DTSTART;TZID=Asia/Kolkata:20210716T171500
DTEND;TZID=Asia/Kolkata:20210716T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1143
DTSTAMP:20230914T125952Z
SUMMARY:The Strahler Number of a Parity Game
DESCRIPTION:Speaker: Thejaswini Raghavan (University of Warwick)\n\nAbstrac
 t: \nThe Strahler number of a rooted tree is the largest height of a perfe
 ct binary tree that is its minor. The Strahler number of a parity game is 
 proposed to be defined as the smallest Strahler number of the tree of any 
 of its attractor decompositions. It is proved that parity games can be sol
 ved in quasi-linear space and in time that is polynomial in the number of 
 vertices n and linear in (d/2k)^k\, where d is the number of priorities an
 d k is the Strahler number. This complexity is quasi-polynomial because th
 e Strahler number is at most logarithmic in the number of vertices. The pr
 oof is based on a new construction of small Strahler-universal trees.\n\nI
 t is shown that the Strahler number of a parity game is a robust\, and hen
 ce arguably natural\, parameter: it coincides with its alternative version
  based on trees of progress measures and—remarkably—with the register 
 number defined by Lehtinen (2018). It follows that parity games can be sol
 ved in quasi-linear space and in time that is polynomial in the number of 
 vertices and linear in (d/2k)^k\, where k is the register number. This sig
 nificantly improves the running times and space achieved for parity games 
 of bounded register number by Lehtinen (2018) and by Parys(2020). The runn
 ing time of the algorithm based on small Strahler-universal trees yields a
  novel trade-off k.log(d/k) = O(log n) between the two natural parameters 
 that measure the structural complexity of a parity game\, which allows sol
 ving parity games in polynomial time. This includes as special cases the a
 symptotic settings of those parameters covered by the results of Calude\, 
 Jain\, Khoussainov\, Li\, and Stephan (2017)\, of Jurdzinski and Lazic (20
 17)\, and of Lehtinen (2018)\, and it significantly extends the range of s
 uch settings\, for example to d = 2^{O(\\sqrt{\\lg n})} and k = O(\\sqrt{\
 \lg n}).\n\nThis is joint work with Laure Daviaud and Marcin Jurdzinski.\n
 \nZoom link: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF
 6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1143
DTSTART;TZID=Asia/Kolkata:20210723T171500
DTEND;TZID=Asia/Kolkata:20210723T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1144
DTSTAMP:20231128T111754Z
SUMMARY:A Computational Approach towards Incentives in Social Choice
DESCRIPTION:Speaker: Rohit Vaish\n\nAbstract: \nGroup decision-making is a 
 ubiquitous phenomenon with diverse applications ranging from political ele
 ctions to recommender systems and from organ exchanges to online marketpla
 ces. Social choice is a subfield of economics that provides a formal frame
 work for studying group decision-making procedures. Classically\, social c
 hoice theory has focused on establishing abstract results concerning the e
 xistence of procedures that provide the desired incentives to the particip
 ating agents. However\, in order to be practically applicable\, the mere e
 xistence of such procedures is not enough---efficient computation is impor
 tant as well. In this talk\, I will illustrate the role of computation in 
 shaping agents' incentives via a case study in fair division. Specifically
 \, I will talk about fair division of indivisible goods\, which is a relev
 ant model for assigning seats in university courses\, allocating public ho
 using units\, and inheritance division. I will present an algorithmic fram
 ework that combines the local search paradigm with the classical Fisher ma
 rket model from economics\, and simultaneously achieves the seemingly inco
 mpatible goals of fairness and economic efficiency. I will conclude with a
 n overview of my other work and future research directions. Bio: Rohit Vai
 sh is a visiting fellow at Tata Institute of Fundamental Research (TIFR). 
 Previously\, he was a postdoctoral researcher at Rensselaer Polytechnic In
 stitute (RPI) and\, prior to that\, received his PhD from Indian Institute
  of Science (IISc). His research is in computational social choice---a rap
 idly growing area at the intersection of theoretical computer science\, ar
 tificial intelligence\, and economics. He has worked on problems in voting
 \, matching\, fair division\, and learning theory\, and his research has b
 een published in top journals like Artificial Intelligence (AIJ) and premi
 er theory and AI conferences such as EC\, SODA\, AAAI\, IJCAI\, and NeurIP
 S among others. In addition\, he is a recipient of Prof. R Narasimhan post
 doctoral award at TIFR\, a best paper award nomination at AAMAS 2018\, and
  the INSPIRE faculty fellowship.\n
URL:https://www.tcs.tifr.res.in/web/events/1144
DTSTART;TZID=Asia/Kolkata:20210726T103000
DTEND;TZID=Asia/Kolkata:20210726T113000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1145
DTSTAMP:20230914T125952Z
SUMMARY:Superpolynomial lower bounds against low-depth algebraic circuits
DESCRIPTION:Speaker: Sébastien Tavenas (Univ. Grenoble Alpes\,\nUniv. Savo
 ie Mont Blanc\,\nCNRS\, LAMA.)\n\nAbstract: \nAn algebraic circuit compute
 s a polynomial using addition and multiplication operators. Understanding 
 the power of algebraic circuits has close connections to understanding gen
 eral computation. It is known that proving lower bounds for algebraic circ
 uits can serve as a stepping stone towards proving general Boolean circuit
  lower bounds.\nDespite this\, not many lower bounds are known for even si
 mple Sigma Pi Sigma (product-depth 1) circuits. Before our work\, the best
  known lower bound for product-depth 1 circuit was (slightly less than) cu
 bic. No lower bounds were known for general product-depth 2 circuits.\nIn 
 this work\, we show the first superpolynomial lower bound for low-product-
 depth algebraic circuits.\nIn the talk\, we discuss the main results and p
 resent the proof ideas used in the proof of the superpolynomial lower boun
 d for product-depth 1 circuits.\n\nThis talk is based on joint work with N
 utan Limaye and Srikanth Srinivasan.\nYouTube link : https://youtu.be/S1_k
 4OxC1bE\n
URL:https://www.tcs.tifr.res.in/web/events/1145
DTSTART;TZID=Asia/Kolkata:20210727T160000
DTEND;TZID=Asia/Kolkata:20210727T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1146
DTSTAMP:20230914T125952Z
SUMMARY:Efficient Stochastic Optimisation using Black Box Importance Sampli
 ng
DESCRIPTION:Speaker: Anand Deo (Singapore University of Technology and Desi
 gn)\n\nAbstract: \nMitigating the effect of tail risk has gained prominenc
 e in a variety of applications where safety is of paramount importance. Ta
 il risk averseness is typically incorporated into standard optimisation mo
 dels by penalising decisions which lead to poor tail performance\, often c
 aptured through the use of measures such as Value at Risk (V@R) and Condit
 ional Value at Risk (CV@R). Operationalising these risk sensitive optimisa
 tion problems however\, requires accurate computation of tail expectations
  of random variables and may incur a large sample requirement. In this tal
 k\, we discuss the use of Black Box Importance Sampling (BBIS) to mitigate
  this difficulty. Specifically\, we show that given black box access to th
 e loss causing covariates\, BBIS significantly reduces the sample complexi
 ty of solving a wide range of tail risk averse optimisation problems. This
  differs from most of the state of the art\, where algorithms to reduce sa
 mple requirements are carefully tuned to the problem at hand. The distribu
 tion/loss agnostic nature of BBIS leads to a wide applicability\, ranging 
 from relatively simple instances such as linear portfolio optimisation to 
 complicated ones such as two stage problems. Numerical simulations support
  our theoretical claims and help establish the utility of BBIS in a number
  of practically relevant settings.\n\nThis talk is based on a number of jo
 int works with Karthyek Murthy\, SUTD. I will not assume any prerequisites
  beyond a basic understanding of probability. Technicalities will be kept 
 to the minimum\, and the exposition will be mostly pictorial.\n\nZoom link
 : https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1146
DTSTART;TZID=Asia/Kolkata:20210730T171500
DTEND;TZID=Asia/Kolkata:20210730T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1147
DTSTAMP:20230914T125952Z
SUMMARY:Exact Sampling & List-Decoding
DESCRIPTION:Speaker: Siddharth Bhandari\n\nAbstract: \nWe will discuss the 
 following results. 1. Exact sampling: We will present an efficient algorit
 hm that\, given a graph of maximum degree $\\Delta$ and a list of at least
  $3\\Delta+1$ colours\, produces a random colouring of the graph that is \
 \emph{exactly} uniformly distributed on the set of all proper colourings. 
 Our algorithm can be generalized to the setting of list colourings\, where
  each vertex is provided with a separate list of at least $3\\Delta+1$ col
 ours. Before this work\, it was known that exact sampling was possible if 
 about $\\Delta^2$ colours were allowed. 2. List-decoding error-correcting 
 codes: In list-decoding\, the decoder\, based on the received word\, is re
 quired to output a small list of messages\, one of which must be the origi
 nal message. We will discuss the following results about list-decoding. (a
 ) Zero-error list decoding capacity of the $q/(q-1)$ channel: We will pres
 ent a lower bound showing that the zero-error list decoding capacity of th
 is channel is exponentially small in $q$ even if the list size is allowed 
 grow as $\\frac{1}{6} q \\ln q$. Previous results showed that the capacity
  was exponentially small if the list size was allowed to grow no larger th
 an $1.58q$. (b) Multiplicity codes: We consider a natural generalization o
 f Reed-Muller codes where at each evaluation point\, one records not only 
 the evaluation of the message polynomial\, but also all its partial deriva
 tives up to a certain order. We will present an efficient algorithm that (
 under mild assumptions) list-decodes multivariate multiplicity codes on ar
 bitrary grids up to their distance. Previously such results were known onl
 y for univariate multiplicity codes. (c) Polynomial ideal codes: A polynom
 ial ideal code is specified by a collection of relatively prime monic poly
 nomials. The encoding is obtained by specifying the remainders of the mess
 age polynomial modulo the various polynomials in the collection. We will d
 escribe an efficient algorithm to list-decode some special polynomial idea
 l codes\, which we \\emph{call affine folded Reed-Solomon codes\,} up to t
 heir distance. Previous results allowed list-decoding up to the distance f
 or folded Reed-Solomon codes\, univariate multiplicity codes and additive 
 folded Reed-Solomon codes\, which are all instances of affine folded Reed-
 Solomon codes. (The above results were obtained in collaborations that inv
 olved the following: Sayantan Chakraborty\, Prahladh Harsha\, Mrinal Kumar
 \, Jaikumar Radhakrishnan\, Madhu Sudan.)\n
URL:https://www.tcs.tifr.res.in/web/events/1147
DTSTART;TZID=Asia/Kolkata:20210803T160000
DTEND;TZID=Asia/Kolkata:20210803T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1148
DTSTAMP:20230914T125952Z
SUMMARY:Regret minimization in heavy-tailed bandits.
DESCRIPTION:Speaker: Shubhada Agrawal\n\nAbstract: \nIn this talk\, we will
  revisit the classical regret-minimization problem in the multi-armed band
 it setting. This problem has been well studied when the arm distributions 
 are restricted to have either bounded support or belong to a single parame
 ter exponential family (distributions characterized by 1 parameter\, for e
 xample\, Gaussian with fixed variance\, Bernoulli distributions\, Poisson 
 distributions\, etc.).  However\, in many applications\, the underlying ar
 m distributions fail to satisfy these simplifying assumptions. We will con
 sider a much general class of arm distributions and work with a weaker ass
 umption that the moments of order $(1 + \\epsilon)$ are uniformly bounded 
 by a known constant B\, for some given $\\epsilon > 0$. We will look at an
  optimal algorithm that matches the lower bound exactly in the in the firs
 t-order term.\n\nRegret-minimization algorithms typically rely on construc
 ting tight confidence intervals for means of the underlying distributions.
  We will also look at new anytime-valid confidence intervals for means\, w
 hich are based on the empirical likelihood principle. Algorithms using the
  MGF-based concentration of the empirical mean for bounded support distrib
 utions (Auer et al.\, 2002)\, or of the robust estimators for mean\, like 
 the truncated empirical mean in the case of heavy-tailed distributions (Bu
 beck et al.\, 2013)\, exist in the literature. We will see exactly where t
 he framework of the optimal algorithm gains over these existing algorithms
  that use MGF-based confidence intervals for the mean.\n\nIf time permits\
 , we will also look at a mixture-martingale-based proof for the validity o
 f the proposed confidence intervals.\n\nThis talk is based on joint work w
 ith Sandeep Juneja and Wouter M. Koolen (the paper can be found here). I w
 ill not assume any prerequisites beyond a basic understanding of probabili
 ty theory.\n\nZoom link: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlp
 ZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1148
DTSTART;TZID=Asia/Kolkata:20210806T171500
DTEND;TZID=Asia/Kolkata:20210806T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1149
DTSTAMP:20230914T125952Z
SUMMARY:Fourier Analytic Techniques in Theoretical Computer Science
DESCRIPTION:Speaker: Somnath Chakraborty\n\nAbstract: \nIn this talk\, we w
 ill discuss the following problems.\n\nProblem 1\n"Suppose that $M$ is unk
 nown finite point set in $\\mathbb R^d$. Suppose $\\omega$ is some distrib
 ution on $M$\, and $\\gamma$ is the standard $d$-dimensional Gaussian. Let
  $X_\\omega$ and $X_\\gamma$ be independent random variables whose distrib
 utions are $\\omega$ and $\\gamma$\, respectively. Can we devise an effici
 ent randomized algorithm that\, given small $\\epsilon\,\\delta>0$\, and i
 ndependent random samples of $X_\\omega+X_\\gamma$\, outputs a distributio
 n $\\hat\\omega$ such that support of $\\hat\\omega$ is a finite point set
  $\\hat M$\, having same cardinality as $M$\, and within distance $\\epsil
 on$ from $M$\, and $\\sup_{m\\in M}|\\omega(m)-\\hat\\omega(\\pi(m))|$ is 
 `small' for some bijection $\\pi:M\\rightarrow\\hat M$\, with success prob
 ability at least $1-\\delta$?"\nProblem 2\n"Suppose that $M$ is a sphere o
 f dimension $d$\, and $\\mbox{Lip}_1(M)$ consists of all the Lipschitz fun
 ctions defined on $M$\, having Lipschitz constant at most 1. Can we devise
  an efficient randomized algorithm that\, given small $\\epsilon\,\\delta>
 0$\, for any input $\\phi\\in \\mbox{Lip}_1(M)$\, outputs a function $\\ha
 t\\phi$ on $M$\, such that $||\\hat\\phi-\\phi||_1\n
URL:https://www.tcs.tifr.res.in/web/events/1149
DTSTART;TZID=Asia/Kolkata:20210811T110000
DTEND;TZID=Asia/Kolkata:20210811T120000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1150
DTSTAMP:20230914T125952Z
SUMMARY:Online Energy Minimization Under A Peak Age of Information Constrai
 nt
DESCRIPTION:Speaker: Kumar Saurav\n\nAbstract: \nWe consider a node where p
 ackets of fixed size are generated at arbitrary intervals. The node is req
 uired to maintain the peak age of information (AoI) at the monitor below a
  threshold by transmitting potentially a subset of the generated packets. 
 At any time\, depending on packet availability and current AoI\, the node 
 can choose the packet to transmit\, and its transmission speed. We conside
 r a power function (rate of energy consumption) that is increasing and con
 vex in transmission speed\, and the objective is to minimize the energy co
 nsumption under the peak AoI constraint at all times. For this problem\, w
 e propose a (customized) greedy policy\, and analyze its competitive ratio
  (CR) by comparing it against an optimal offline policy by deriving some s
 tructural results. We show that for polynomial power functions\, the CR up
 per bound for the greedy policy is independent of the system parameters\, 
 such as the peak AoI\, packet size\, time horizon\, or the number of packe
 ts generated. Also\, we derive a lower bound on the competitive ratio of a
 ny causal policy\, and show that for exponential power functions (e.g.\, S
 hannon rate function)\, the competitive ratio of any causal policy grows e
 xponentially with increase in the ratio of packet size to peak AoI.\n\nThi
 s talk is based on the joint work with Prof. Rahul Vaze\, set to appear in
  the Proc. WiOpt 2021.\n\nZoom link: https://zoom.us/j/93889521556?pwd=eEF
 JWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1150
DTSTART;TZID=Asia/Kolkata:20210813T171500
DTEND;TZID=Asia/Kolkata:20210813T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1151
DTSTAMP:20230914T125952Z
SUMMARY:Criticality of boolean functions and Entropy Switching lemma for DN
 Fs
DESCRIPTION:Speaker: Tulasi mohan Molli\n\nAbstract: \nA p-random restricti
 on is a random partial input obtained by independently leaving each input 
 variable unset with probability p setting them to either 0\,1 with (1-p)/2
  each.\n\nCriticality of a boolean function f is the inverse of the probab
 ility p at which the decision tree depth t of a random restriction of f go
 es down exponentially in t.The ground breaking work of Hastad’s Switchin
 g lemma is a bound on criticality of CNFs and DNFs. Rossman defined the no
 tion of criticality and showed its connection to average case lower bounds
 \, fourier tail bounds\, and decision tree size.\n\nIn this talk we will s
 ee implications of bounds on criticality to average case lower bounds\, Fo
 urier tail bounds and decision tree size and an Entropy Switching lemma fo
 r DNFs due to Rossman.\n\nZoom link:\nhttps://zoom.us/j/93889521556?pwd=eE
 FJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1151
DTSTART;TZID=Asia/Kolkata:20210820T171500
DTEND;TZID=Asia/Kolkata:20210820T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1152
DTSTAMP:20230914T125952Z
SUMMARY:Collapses and Persistent Homology
DESCRIPTION:Speaker: Siddharth Pritam (DataShape\, Inria)\n\nAbstract: \nWe
  introduce two new approaches to compute the Persistent Homology (PH) of a
  sequence of simplicial complexes. The basic idea is to simplify the compl
 exes of the input sequence by using special types of collapses (strong and
  edge collapse) and to compute the PH of an induced sequence of smaller si
 ze that has the same PH as the initial one. Our first approach uses strong
  collapse which is introduced by J. Barmak and E.Miniam [DCG (2012)]. Stro
 ng collapse consists of removal of special vertices called dominated verti
 ces from a simplicial complex. In the second approach\, we extend the noti
 ons of dominated vertex to a simplex of any dimension. Domination of edges
  appears to be very powerful and we study it in the case of flag complexes
  in more detail. As a result and as demonstrated by numerous experiments o
 n publicly available data sets\, our approaches are extremely fast and mem
 ory efficient in practice.\n
URL:https://www.tcs.tifr.res.in/web/events/1152
DTSTART;TZID=Asia/Kolkata:20210824T160000
DTEND;TZID=Asia/Kolkata:20210824T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1153
DTSTAMP:20230914T125952Z
SUMMARY:An Asymptotic Analysis of Risk in Financial Systems - Analysis and 
 Algorithms
DESCRIPTION:Speaker: Anand Deo\n\nAbstract: \nOver the past few decades\, p
 robabilistic models have become an important tool for under-standing risks
  and decision making in practical financial systems. In the design of suc
 h systems one often wishes to relate the risk to the statistics of underly
 ing stochasticity. However\, this task is complicated by the fact that rea
 listic financial systems are complex\, and undesirable events in them are
  often rare. A large body of research has been devoted to understanding th
 e nature of such rare events\, and how they relate to the stochasticity a
 ffecting the system. In this talk\, we undertake a detailed study of thes
 e aspects in order to develop structural insights on a number of financia
 l systems of practical interest. Our main contributions are as below:\nI. 
 We discuss the development of a closed form\, interpretable parameter esti
 mation technique for predicting defaults of financial firms. Typically\,
  one uses maximum likelihood estimation (MLE) for predicting the firm def
 ault probabilities. We prove that our estimator is almost as accurate as t
 he MLE\, verify our result empirically on a sample of US corporate data\, 
 and showcase the computational/interpretative benefits of our estimator o
 ver the MLE.\nII. We develop a statistically consistent estimator for cond
 itional value-at-risk (CVaR) based optimization objectives and their gradi
 ents. Unlike the state-of-the-art sample average approximations\, the prop
 osed approximation scheme exploits the self-similarity of heavy-tailed dis
 tributions to extrapolate data from lower quantiles\, thereby reducing dat
 a requirements for accurate estimation.\nIII. Motivated by the increasing 
 adoption of models which facilitate automation in risk management and deci
 sion-making\, we present a novel importance sampling (IS) scheme for measu
 ring distribution tails of objectives. Conventional efficient IS approache
 s suffer from feasibility concerns due to the need to intricately tailor 
 the sampler to the underlying probability distribution and the objective. 
 We overcome this challenge in the proposed black-box scheme by automating 
 the selection of an effective IS distribution with a transformation that 
 implicitly learns and replicates the concentration properties observed in 
 less rare samples.\nIV. We develop a limiting representation for an interc
 onnected banking network in presence of partial information. Practical ban
 king networks are large and complicated\, and one searches for simple limi
 ting representations (as the network size goes to infinity). We character
 ise the wealth of banks in a large network in terms of a simple\, one dime
 nsional distributional fixed point\, which we show is amenable to Monte C
 arlo simulation.\nThis talk is based on joint work with Sandeep Juneja and
  Karthyek Murthy.\n\nThe zoom link for the talk is https://zoom.us/j/93128
 173558?pwd=SXRkdFE1MVBnc2hSSEtvbHRIZG4yQT09\n
URL:https://www.tcs.tifr.res.in/web/events/1153
DTSTART;TZID=Asia/Kolkata:20210825T183000
DTEND;TZID=Asia/Kolkata:20210825T193000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1154
DTSTAMP:20230914T125952Z
SUMMARY:Paper Presentation
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nPaper: Nachum Dershowitz a
 nd Yuri Gurevich\, "A Natural Axiomatization of Computability and Proof of
  Church's Thesis"\nhttps://doi.org/10.2178/bsl/1231081370\n
URL:https://www.tcs.tifr.res.in/web/events/1154
DTSTART;TZID=Asia/Kolkata:20210827T100000
DTEND;TZID=Asia/Kolkata:20210827T110000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1155
DTSTAMP:20230914T125952Z
SUMMARY:Paper Presentation
DESCRIPTION:Speaker: Hari Krishnan P A\n\nAbstract: \n"Paper: Yuchen Zhang\
 , John C Duchi\, Michael I Jordan\, Martin J Wainwright\, Information-theo
 retic lower bounds for distributed statistical estimation with communicati
 on constraints"\nhttps://proceedings.neurips.cc/paper/2013/hash/d6ef5f7fa9
 14c19931a55bb262ec879c-Abstract.html\n
URL:https://www.tcs.tifr.res.in/web/events/1155
DTSTART;TZID=Asia/Kolkata:20210827T110000
DTEND;TZID=Asia/Kolkata:20210827T120000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1156
DTSTAMP:20230914T125952Z
SUMMARY:Paper Presentation
DESCRIPTION:Speaker: Praveen Sai Chinthaginjala\n\nAbstract: \nPaper: Nikhi
 l R. Devanur\, Zhiyi Huang. "Primal Dual Gives Almost Optimal Energy-Effic
 ient Online Algorithms"\nhttps://dl.acm.org/doi/abs/10.1145/3155297\n
URL:https://www.tcs.tifr.res.in/web/events/1156
DTSTART;TZID=Asia/Kolkata:20210827T120000
DTEND;TZID=Asia/Kolkata:20210827T130000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1157
DTSTAMP:20230914T125952Z
SUMMARY:Paper Presentation
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nPaper: Michael Saks an
 d Rahul Santhanam\, "Circuit Lower Bounds from NP-Hardness of MCSP Under T
 uring Reductions"\nhttps://drops.dagstuhl.de/opus/volltexte/2020/12578/\n
URL:https://www.tcs.tifr.res.in/web/events/1157
DTSTART;TZID=Asia/Kolkata:20210827T140000
DTEND;TZID=Asia/Kolkata:20210827T150000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1158
DTSTAMP:20230914T125952Z
SUMMARY:Project: An algorithm for the multiplicity Schwartz-Zippel lemma
DESCRIPTION:Speaker: Ashutosh Shankar\n\nAbstract: \nThe multiplicity Schwa
 rtz-Zippel lemma provides a bound on the total multiplicity of zeroes of a
  low-degree polynomial within a product set. It implies that multiplicity 
 codes\, which can be thought of as generalizations of Reed-Muller codes th
 at consist of evaluations of derivatives along with the evaluations of the
  polynomial - have good distance. There has been progress towards the prob
 lem of algorithmizing this lemma - that is\, unique decoding to find the c
 losest codeword given a possibly corrupted received word - for certain cas
 es such as the product set being a vector space\, or the number of derivat
 ives given being large. In this project\, we describe an algorithm for the
  multiplicity Schwartz-Zippel lemma for general product sets and any numbe
 r of derivatives. For the purposes of this project\, we restrict ourselves
  to the bivariate case. Our algorithm is motivated by Kim and Kopparty’s
  algorithm for decoding Reed-Muller codes over product sets. In the proces
 s of adapting it\, we develop new notions of weight and distance\, as well
  as a new approach to analysing Forney’s classical algorithm for decodin
 g concatenation codes. The results presented in this work are based on joi
 nt work with Siddharth Bhandari\, Prahladh Harsha and Mrinal Kumar (IIT Bo
 mbay).\n
URL:https://www.tcs.tifr.res.in/web/events/1158
DTSTART;TZID=Asia/Kolkata:20210827T150000
DTEND;TZID=Asia/Kolkata:20210827T160000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1159
DTSTAMP:20230914T125952Z
SUMMARY:The complexity of approximating Satisfiable CSPs
DESCRIPTION:Speaker: Amey Bhangale (University of California)\n\nAbstract: 
 \nRaghavendra's famous result from 2008 fully characterizes the inapproxim
 ability of every maximum constraint satisfaction problem (Max-CSP). Howeve
 r\, the result inherently loses perfect completeness. This means that it d
 oes not say anything about the complexity of solving satisfiable Max-CSP i
 nstances.\n\nIn this talk\, I will discuss inapproximability of linear equ
 ations over non-abelian groups. We show that even if the instance is satis
 fiable\, it is NP-hard to beat the random assignment algorithm for 'perfec
 t groups'. This is in stark contrast to the problem of solving linear equa
 tions over abelian groups\, in which case we know how to find a satisfying
  assignment\, if it exists\, efficiently. We also give tight inapproximabi
 lity results for solving linear equations over any non-abelian group. \n\n
 The proof techniques involve Fourier analysis over non-abelian groups and 
 lots of applications of the Cauchy-Schwarz inequality.\n\nThis is joint wo
 rk with Subhash Khot.\n
URL:https://www.tcs.tifr.res.in/web/events/1159
DTSTART;TZID=Asia/Kolkata:20210831T160000
DTEND;TZID=Asia/Kolkata:20210831T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1160
DTSTAMP:20230914T125952Z
SUMMARY:Linear Matroid Intersection is in Pseudo-deterministic NC
DESCRIPTION:Speaker: Sumanta Ghosh (IIT Bombay --> Caltech)\n\nAbstract: \n
 A pseudo-deterministic NC algorithm for a search problem is an RNC algorit
 hm that\, for a given input\, outputs a fixed solution with high probabili
 ty. In this talk\, we describe a pseudo-deterministic NC algorithm for the
  linear matroid intersection problem. Our work strengthens the RNC algorit
 hm for the linear matroid intersection given by Narayanan\, Saran and Vazi
 rani (NSV'94). It also generalizes the pseudo-deterministic NC algorithm f
 or the bipartite matching (due to Goldwasser and Grossman 2017) to linear 
 matroid intersection.\nIt is a joint work with Rohit Gurjar.\n\nZoom link:
  https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1160
DTSTART;TZID=Asia/Kolkata:20210903T171500
DTEND;TZID=Asia/Kolkata:20210903T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1161
DTSTAMP:20230914T125952Z
SUMMARY:Quasi-transitive tilings of the plane
DESCRIPTION:Speaker: Arun Maiti (Indian Institute of Science\, Bangalore.)\
 n\nAbstract: \nTiling of a surface is acted upon by its automorphism group
 . The tilings with single vertex orbit\,  the transitive tilings\, are wel
 l studied since antiquity. In this talk I will present a class of locally 
 symmetric tilings of the plane that has finitely many orbits but not trans
 itive. Along the way I will talk about some known and a few new results ab
 out locally symmetric and pseudo-symmetric tilings of the plane.\n
URL:https://www.tcs.tifr.res.in/web/events/1161
DTSTART;TZID=Asia/Kolkata:20210907T160000
DTEND;TZID=Asia/Kolkata:20210907T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1162
DTSTAMP:20230914T125953Z
SUMMARY:Commuting Matrices and Multivariate Multiplicity
DESCRIPTION:Speaker: Anamay Tengse\n\nAbstract: \nWe know that for matrices
  A and B\, AB is not the same as BA in general. But suppose B is a polynom
 ial in A\, like B = A^2 - 3A + I (note I = A^0). Then AB is indeed the sam
 e as BA. Some natural questions follow for a set S of (square) matrices th
 at commute with each other.\n1. Does there always exist an A in S that "ge
 nerates" the rest via polynomials?\n2. Since diagonal matrices commute wit
 h each other\, is it the case that we can (simultaneously) diagonalise all
  matrices in S?\n3. If (1) and (2) are false\, then what do these non-triv
 ial sets S look like?\nIn this talk we will see an elegant characterisatio
 n of commuting matrices which follows from the works of Marinari\, Möller
  and Mora (1993)\, and Möller and Stetter (1995). Similar in spirit to qu
 estion (1) above\, the characterisation involves multivariate polynomials 
 and uses a notion of "multiplicity of a polynomial at a point" that is sli
 ghtly non-standard in CS.\n\nZoom link:\nhttps://zoom.us/j/93889521556?pwd
 =eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n \n
URL:https://www.tcs.tifr.res.in/web/events/1162
DTSTART;TZID=Asia/Kolkata:20210917T171500
DTEND;TZID=Asia/Kolkata:20210917T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1163
DTSTAMP:20230914T125953Z
SUMMARY:Resource Allocation Problems in Large-Scale Networks
DESCRIPTION:Speaker: Abhishek Sinha (Indian Institute of Technology Madras)
 \n\nAbstract: \nOptimal resource allocation in networks gives rise to some
  of the most fundamental problems at the intersection of algorithms\, stoc
 hastic processes\, and learning. In this talk\, we will discuss our recent
  contributions to three canonical resource allocation problems\, namely ca
 ching\, routing\, and scheduling. First\, we will consider the optimal cac
 hing problem for single and networked caches. However\, instead of minimiz
 ing the competitive ratio - the classical metric of choice for caching pro
 blems\, we will look at the problem from an online learning perspective th
 at minimizes regret. We will show that this viewpoint leads to an entirely
  new class of caching policies with provably better performance than the c
 lassical ones. We will also discuss some converse results on the regret lo
 wer bounds for this problem. Next\, we will discuss the problem of through
 put-optimal dynamic routing of a broad class of traffic\, including unicas
 t\, multicast\, broadcast\, and anycast flows on a network with arbitrary 
 link scheduling constraints. We will present a unified algorithmic framewo
 rk based on precedence relaxations\, leading to an efficient policy that p
 rovably outperforms the state-of-the-art Backpressure routing algorithm. F
 inally\, we will discuss a user scheduling problem for reliable and fresh 
 information delivery over unreliable wireless channels. However\, contrary
  to the existing literature\, which predominantly considers stochastic cha
 nnels\, we investigate a non-stationary environment modeled using a new ad
 versarial framework. We will describe competitive algorithms in this setti
 ng along with some approximately tight lower bounds. We will supplement ea
 ch part of the talk with a set of open problems.\n\nBio: Abhishek Sinha is
  currently working as an Assistant Professor in the Department of Electric
 al Engineering at the Indian Institute of Technology Madras. He received h
 is Ph.D. degree from the Massachusetts Institute of Technology in 2017\, w
 here he was associated with the Laboratory for Information and Decision Sy
 stems (LIDS). After his Ph.D.\, Abhishek worked as a senior engineer at Qu
 alcomm Research\, San Diego\, in the 5G standardization group. He obtained
  his M.E. degree in Telecommunication Engg. from the Indian Institute of S
 cience\, Bangalore\, and his B.E. degree in Electronics and Telecommunicat
 ion Engg. from Jadavpur University\, Kolkata\, India. He is a recipient of
  the Best Paper Award in INFOCOM 2018\, the Best Paper Award in MobiHoc 20
 16\, Prof. Jnansaran Chatterjee memorial gold medal\, and T.P. Saha Memori
 al gold-centered silver medal from Jadavpur University and Jagadis Bose Na
 tional Science Talent Search (JBNSTS) scholarship\, Kolkata\, India. His a
 reas of interest include networks\, information theory\, theoretical machi
 ne learning\, and applied probability.\n
URL:https://www.tcs.tifr.res.in/web/events/1163
DTSTART;TZID=Asia/Kolkata:20210921T160000
DTEND;TZID=Asia/Kolkata:20210921T171500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1164
DTSTAMP:20230914T125953Z
SUMMARY:Parallel Repetition for the GHZ Game: A Simpler Proof
DESCRIPTION:Speaker: Uma Girish (Princeton University)\n\nAbstract: \nWe gi
 ve a new proof of the fact that the parallel repetition of the (3-player) 
 GHZ game reduces the value of the game to zero polynomially quickly. That 
 is\, we show that the value of the n-fold parallel repetition of the GHZ g
 ame is at most n^{-\\Omega(1)}. This was first established by Holmgren and
  Raz [HR20]. We present a new proof of this theorem that we believe to be 
 simpler and more direct. Unlike most previous works on parallel repetition
 \, our proof makes no use of information theory\, and relies on the use of
  Fourier analysis. The GHZ game [GHZ89] has played a foundational role in 
 the understanding of quantum information theory\, due in part to the fact 
 that quantum strategies can win the GHZ game with probability 1. It is pos
 sible that improved parallel repetition bounds may find applications in th
 is setting. Recently\, Dinur\, Harsha\, Venkat\, and Yuen [DHVY17] highlig
 hted the GHZ game as a simple three-player game\, which is in some sense m
 aximally far from the class of multi-player games whose behavior under par
 allel repetition is well understood. Dinur et al. conjectured that paralle
 l repetition decreases the value of the GHZ game exponentially quickly\, a
 nd speculated that progress on proving this would shed light on parallel r
 epetition for general multi-player (multi-prover) games. This is based on 
 a joint work with Justin Holmgren\, Kunal Mittal\, Ran Raz and Wei Zhan.\n
 YouTube link : https://www.youtube.com/watch?v=jxQ81fDMpOU\n
URL:https://www.tcs.tifr.res.in/web/events/1164
DTSTART;TZID=Asia/Kolkata:20210928T190000
DTEND;TZID=Asia/Kolkata:20210928T200000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1165
DTSTAMP:20230914T125953Z
SUMMARY:The Space Complexity of Sum Labelling
DESCRIPTION:Speaker: Kshitij Gajjar (National University of Singapore)\n\nA
 bstract: \nHow does one store a graph in the database? Typically the verti
 ces are labelled by a set {1\, 2\, ...\, n}. The edges can be denoted in m
 any different ways: adjacency matrix\, incidence matrix\, adjacency list\,
  to name a few. But what if the vertices are labelled in a more creative w
 ay\, such that the labels of the vertices themselves denote their adjacenc
 ies? This eliminates the need for storing the edges! This topic is part of
  a heavily researched field called graph labelling\, with connections to c
 oding theory and information theory. In this talk\, we will explore a type
  of graph labelling known as sum labelling. This is joint work with Hennin
 g Fernau (https://eccc.weizmann.ac.il/report/2021/114).\n\nZoom Link: http
 s://zoom.us/j/93889521556pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1165
DTSTART;TZID=Asia/Kolkata:20211001T171500
DTEND;TZID=Asia/Kolkata:20211001T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1166
DTSTAMP:20230914T125953Z
SUMMARY:Computationally Secure Computation from One-Way Noisy Communication
DESCRIPTION:Speaker: Varun Narayanan (Technion)\n\nAbstract: \nCan a sender
  encode a pair of messages (m0\, m1) jointly\, and send their encoding ove
 r (say) a binary erasure channel\, so that the receiver can decode exactly
  one of the two messages and the sender does not know which one?\nGarg et 
 al. (Crypto 2015) showed that this is information-theoretically impossible
 . We show how to circumvent this impossibility by assuming that the receiv
 er is computationally bounded\, settling for an inverse- polynomial securi
 ty error (which is provably necessary)\, and relying on ideal obfuscation.
  Our solution creates a "computational anti-correlation" between the event
 s of receiving m0 and receiving m1 by exploiting the anti-concentration of
  the binomial distribution.\nThe ideal obfuscation primitive in our constr
 uction can either be directly realized using (stateless)  tamper-proof har
 dware\, yielding an unconditional result.\nAs a corollary\, we get similar
  feasibility results for general secure computation of sender-receiver fun
 ctionalities by leveraging the completeness of the above random oblivious 
 transfer functionality.\n\nZoom link: \nhttps://zoom.us/j/93889521556?pwd=
 eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1166
DTSTART;TZID=Asia/Kolkata:20211008T171500
DTEND;TZID=Asia/Kolkata:20211008T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1167
DTSTAMP:20230914T125953Z
SUMMARY:A search-to-decision reduction for minimizing formulas
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nThe Minimum Circuit Si
 ze problem is a fundamental problem in theoretical computer science\, conn
 ecting cryptography\, learning theory\, structural complexity\, etc.\, One
  of the longstanding open problems is whether determining the size of a sm
 allest circuit for a boolean function is equivalent to finding a minimum-s
 ized circuit for the function. If one can find a minimum-sized circuit\, o
 ne can certainly determine the minimum size required to compute a given fu
 nction. The converse -- a search-to-decision reduction -- is not known. We
  haven't yet ruled out the possibility that the decision problem takes lin
 ear time but the search problem requires exponential time.\n\nIlango\, in 
 his CCC2020 paper\, makes progress in connecting the search and decision c
 omplexity for minimizing formulas for any given boolean function. The main
  result that we'll discuss today is that given an oracle to MFSP (Minimum 
 Formula Size Problem)\, one can solve Search-MFSP in time polynomial in th
 e length N of the input (which is the truth table of the function f) and t
 he number t of "near-optimal" formulas for f\, in time O(poly(N\,t)). Whil
 e this quantity t is not well-understood\, we will see how this result giv
 es us a deterministic O(2^{N/loglog(N)})-time oracle algorithm for solving
  Search-MFSP on all but a o(1) fraction of instances.\n \nZoom Link:  ht
 tps://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1167
DTSTART;TZID=Asia/Kolkata:20211022T171500
DTEND;TZID=Asia/Kolkata:20211022T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1168
DTSTAMP:20230914T125953Z
SUMMARY:The Complexity of Simple Stochastic Games
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nA Simple Stochastic Game i
 s a game with a reachability objective played by two players on a directed
  graph. Each vertex of the graph is either controlled by one of the player
 s or is a probabilistic vertex. The game begins by placing a token on the 
 start vertex. In each turn\, if the token is on a probabilistic vertex\, t
 hen the token moves to one of its out-neighbours uniformly at random. Else
 \, the player controlling the vertex chooses an out-neigbour to move the t
 oken to. Player 1 wins if the token ever reaches the target vertex and Pla
 yer 0 wins otherwise.\nGiven an SSG\, we would like to find out which play
 er has a greater probability of winning the game. Condon (1992) showed tha
 t this problem is in NP \\intersection coNP. There are some special cases 
 of the game for which the problem can be solved in polynomial time. In tod
 ay's talk\, we discuss proofs of the same.\nLink to paper: https://doi.org
 /10.1016/0890-5401(92)90048-K\nZoom Link:  https://zoom.us/j/93889521556?
 pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1168
DTSTART;TZID=Asia/Kolkata:20211029T171500
DTEND;TZID=Asia/Kolkata:20211029T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1169
DTSTAMP:20230914T125953Z
SUMMARY:Finding a satisfactory permutation
DESCRIPTION:Speaker: Kshitij Gajjar (National University of Singapore)\n\nA
 bstract: \nYou have n candidates to fill up n vacant positions in an offic
 e. The question is which candidate gets which position? To decide this\, y
 ou ask non-candidates to vote. There are n! ways to allocate the positions
 \, each corresponding to a permutation over [n]. Different voters may come
  up with different permutations\, and your task is to find a permutation t
 hat satisfies all the voters (or minimizes their dissatisfaction).\nThis p
 roblem has several applications\, namely in computational biology\, DNA st
 orage systems\, speech recognition\, social choice theory\, and classifica
 tion. Surprisingly\, no poly(n)-time algorithm is known for this problem\,
  even when there are only 4 voters. In this talk\, I will present a 1.5-ap
 proximation algorithm for this problem\, whose runtime is poly(n) time whe
 n the number of voters is a constant. This is joint work with Diptarka Cha
 kraborty (NUS) and Agastya Vibhuti Jha (EPFL).\n\nZoom link: https://zoom.
 us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1169
DTSTART;TZID=Asia/Kolkata:20211105T171500
DTEND;TZID=Asia/Kolkata:20211105T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1170
DTSTAMP:20230914T125953Z
SUMMARY:Upper bound on randomness complexity of private computations of AND
DESCRIPTION:Speaker: Hari Krishnan P A\n\nAbstract: \nIn a secure multi-par
 ty computation problem\, players are required to compute a function of the
 ir private inputs without revealing any extra information about this input
  to other players. Randomness complexity is the number of random bits used
  by the protocol which enables such a computation. It was previously known
  that XOR can be computed using only one random bit for any number of play
 ers.\n\nIn this talk\, we will see the result by Kushilevitz et al. which 
 shows that there exists a protocol that can privately compute the Boolean 
 function AND with 8 random bits for n>3 players and 7 bits for n=3 players
  under a semi-honest adversarial setting.\n\nLink to the paper: https://ep
 ubs.siam.org/doi/pdf/10.1137/20M1314197\n\nZoom link:  https://zoom.us/j/9
 3889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1170
DTSTART;TZID=Asia/Kolkata:20211112T171500
DTEND;TZID=Asia/Kolkata:20211112T181500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1171
DTSTAMP:20230914T125953Z
SUMMARY:Seroprevalence-based vaccination strategies: A combined transmissio
 n and operational modeling approach.
DESCRIPTION:Speaker: Sarang Deo (Indian School of Business)\n\nAbstract: \n
 Many low- and middle-income countries face limited supply of vaccines. In 
 such situations it is imperative to devise vaccination rollout strategies 
 that maximize the cost-effectiveness of these limited vaccine stocks. For 
 instance\, it may seem that selectively targeting regions with lower serop
 revalence (e.g.\, rural areas) may be more effective in protecting more su
 sceptible individuals than regions with higher seroprevalence (e.g.\, urba
 n areas) that have fewer susceptible individuals. However\, these areas ma
 y also have different reproduction rates which are the core drivers of dif
 ferent seroprevalence. Similarly\, cost of supplying vaccines to these reg
 ions may be different. As a result\, it is not obvious if\, and when\, suc
 h seroprevalence driven strategies may be more effective than uniform vacc
 ine rollout. We develop a modeling framework that combines transmission mo
 deling with supply chain modeling to answer this question and illustrate i
 ts utility using data on COVID-19 pandemic for the state of Punjab.\n\nYou
 Tube link: https://www.youtube.com/watch?v=g3i1I-8lB1Q\n \n
URL:https://www.tcs.tifr.res.in/web/events/1171
DTSTART;TZID=Asia/Kolkata:20211116T160000
DTEND;TZID=Asia/Kolkata:20211116T170000
LOCATION:Via Zoom (please write to supriya.pottipati@tifr.res.in for zoom l
 ink)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1172
DTSTAMP:20230914T125953Z
SUMMARY:On the Existence of EFX Allocations
DESCRIPTION:Speaker: Bhaskar Ray Chaudhury (University of Illinois at Urban
 a-Champaign)\n\nAbstract: \nWe consider the problem of dividing indivisibl
 e resources among a set of agents ``fairly''. Our underlying fairness noti
 on is envy-freeness up to any good (EFX)\, where no agent envies another f
 ollowing the removal of any single good from the other's bundle. Despite s
 ubstantial effort from the community\, the existence of EFX allocations ha
 s not been settled. In this talk\, we elaborate the proof of existence of 
 certain relaxations of EFX allocations and the existence  of EFX allocatio
 ns when there are only three agents. In the end\, we also reduce the probl
 em of finding improved relaxations of EFX allocations to a problem in extr
 emal graph theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1172
DTSTART;TZID=Asia/Kolkata:20211123T173000
DTEND;TZID=Asia/Kolkata:20211123T183000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1173
DTSTAMP:20230914T125953Z
SUMMARY:Hardness and Independence of Polynomials
DESCRIPTION:Speaker: Prerona  Chatterjee\n\nAbstract: \nAlgebraic Complexit
 y Theory is a field in which one studies complexity theoretic questions su
 rrounding algebraic objects. In this talk we will be broadly discussing tw
 o such problems.\nThe first problem is showing lower bounds for explicit p
 olynomials against various algebraic computational models. The most natura
 l and well studied models of computation are algebraic circuits\, algebrai
 c branching programs (ABPs) and algebraic formulas. With respect to provin
 g lower bounds against these models\, we show the following results.\n1. A
 ny algebraic branching program computing \\sum_{i=1}^n x_i^n must have at 
 least n^2 vertices. The previous best known lower bound was \\Omega(n log 
 n) on the number of edges for the same polynomial [Baur-Strassen].\n2. Any
  formula computing the elementary symmetric polynomial of degree 0.1n must
  have at least n^2 vertices. The previous best lower bound for any multili
 near polynomial was \\Omega(n^2/log n) [Nechiporuk\, Kalorkoti]. It can al
 so be shown that previous known methods can not prove a bound better than 
 \\Omega(n^2/log n) for any explicit multilinear polynomial.\nThis is joint
  work with Mrinal Kumar\, Adrian She and Ben Lee Volk.\nAlong with proving
  lower bounds against these models\, studying their relative powers is als
 o an important problem in algebraic circuit complexity. It is known that f
 ormulas can be efficiently simulated by ABPs and checking whether the conv
 erse of this statement holds is a central question in the field. We make p
 rogress towards solving this problem in the non-commutative setting\, wher
 e we show a tight super-polynomial separation between ABPs and some struct
 ured formulas.\nThe second problem that we are interested in relates the q
 uestions of checking whether a given algebraic compuational model is compu
 ting the zero polynomial or not and checking whether a given set of polyno
 mials is algebraically independent or not. The connection between these qu
 estions is via the notion of Faithful Homomorphisms. Although construction
  of faithful homomorphisms were known when the underlying field had charac
 teristic zero [Beecken-Mittman-Saxena\, Agrawal-Saha-Saptharishi-Saxena]\,
  they were not known in the setting where the underlying field had finite 
 characteristic since efficient algorithms to check algebraic indepndence w
 ere not known in this setting. Following up on the work of Pandey\, Saxena
  and  Sinhababu\, we construct faithful homomorphisms over fields of fini
 te characetristics in some restricted settings and as a consequence show e
 fficient polynomial identity tests for related models of computation. This
  is joint work with Ramprasad Saptharishi.\n\nZoom link: https://zoom.us/j
 /95369375923?pwd=VTlRNzNWUEdsbVRNb3RiSC9NdnRGZz09\n
URL:https://www.tcs.tifr.res.in/web/events/1173
DTSTART;TZID=Asia/Kolkata:20211126T173000
DTEND;TZID=Asia/Kolkata:20211126T183000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1174
DTSTAMP:20230914T125953Z
SUMMARY:Partial Function Extension with Applications to Property Testing an
 d Learning
DESCRIPTION:Speaker: Gunjan Kumar\n\nAbstract: \nPartial function extension
  is a basic problem that underpins multiple research topics in optimizatio
 n\, including learning\, property testing\, and game theory. Here\, we are
  given a partial function consisting of some points from a domain and a fu
 nction value at each point. Our objective is to determine if this partial 
 function can be extended to a function defined on the domain\, that additi
 onally satisfies a given property\, such as monotonicity. We formally stud
 y partial function extension for various complement-free functions.\nOur c
 ontributions are twofold. Firstly\, for the properties studied\, we give a
  combinatorial characterization and bounds on the complexity of partial fu
 nction extension. Secondly\, we develop new connections between partial fu
 nction extension and learning and property testing\, and use these to give
  new results for these problems.\nJoin Zoom Meeting\nhttps://zoom.us/j/967
 20853429?pwd=ZUFFdzYvSmQzMWRNOG9PZVNzMHJpdz09\nMeeting ID: 967 2085 3429\n
 Passcode: 869836\n
URL:https://www.tcs.tifr.res.in/web/events/1174
DTSTART;TZID=Asia/Kolkata:20211202T180000
DTEND;TZID=Asia/Kolkata:20211202T190000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1175
DTSTAMP:20230914T125953Z
SUMMARY:Online Bipartite Matching and Adwords
DESCRIPTION:Speaker: Vijay V. Vazirani (University of California\, Irvine)\
 n\nAbstract: \nOver the last three decades\, the online bipartite matching
  (OBM) problem has emerged as a central problem in the area of Online Algo
 rithms. Perhaps even more important is its role in the area of Matching-Ba
 sed Market Design. The resurgence of this area\, with the revolutions of t
 he Internet and mobile computing\, has opened up novel\, path-breaking app
 lications\, and OBM has emerged as its paradigmatic algorithmic problem.\n
 In a 1990 joint paper with Richard Karp and Umesh Vazirani\, we gave an op
 timal algorithm\, called RANKING\, for OBM\, achieving a competitive ratio
  of (1 – 1/e)\; however\, its analysis was difficult to comprehend. Over
  the years\, several researchers simplified the analysis.\nWe will start b
 y presenting a “textbook quality” proof of RANKING. Its simplicity rai
 ses the possibility of extending RANKING all the way to a generalization o
 f OBM called the adwords problem. This problem is both notoriously difficu
 lt and very significant\, the latter because of its role in the AdWords ma
 rketplace of Google. We will show how far this endeavor has gone and what 
 remains. We will also provide a broad overview of the area of Matching-Bas
 ed Market Design and pinpoint the role of OBM. \nBased on:\nhttps://arxiv
 .org/pdf/2107.10777.pdf\nBio: Vijay Vazirani got his undergraduate degree 
 from MIT in 1979 and his PhD from the University of California\, Berkeley 
 in 1983. He is currently a Distinguished Professor at the University of Ca
 lifornia\, Irvine.\nVazirani has made fundamental contributions to several
  areas of the theory of algorithms\, including algorithmic matching theory
 \, approximation algorithms and algorithmic game theory\, as well as to co
 mplexity theory\, in which he established\, with Les Valiant\, the hardnes
 s of unique solution instances of NP-complete problems. Over the last four
  years\, he has been working on algorithms for matching markets. He is one
  of the founders of algorithmic game theory.\nIn 2001 he published Approxi
 mation Algorithms\, which is widely regarded as the definitive book on the
  topic. In 2007\, he published the co-edited book Algorithmic Game Theory.
  Another co-edited book\, Online and Matching-Based Market Design\, will b
 e published by Cambridge University Press in early 2022\; see its flyer: 
 \nhttps://www.ics.uci.edu/~vazirani/flyer.pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1175
DTSTART;TZID=Asia/Kolkata:20211207T160000
DTEND;TZID=Asia/Kolkata:20211207T170000
LOCATION:in person @ R.No. AG-69 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1176
DTSTAMP:20230914T125953Z
SUMMARY:Secure Multiparty Computation with Limited Connectivity
DESCRIPTION:Speaker: Varun Narayanan\n\nAbstract: \nInformation theoretical
 ly secure multiparty computation (MPC) is a central primitive in modern cr
 yptography.\nIt enables mutually distrusting parties to collaboratively pe
 rform computations on their combined data by ensuring that each party's da
 ta is kept private from the others.\nThis is achieved by designing communi
 cation protocols which allow the parties to collectively simulate an incor
 ruptible trusted party\, who privately receives inputs from the parties\, 
 computes the pre-agreed functionality\, and delivers the outputs to the ap
 propriate parties privately.\nThe subject of this dissertation is MPC when
  there is limited connectivity in the communication network available to t
 he participants.\nOur motivations and the progress we made in addressing t
 hem follows:\n- In many practical scenarios\, the parties may only have ac
 cess to a communication network with limited connectivity\, in that\, not 
 every pair of parties can communicate privately and reliably with each oth
 er.\nWe characterize the conditions under which a pair of parties can comp
 ute any functionality with information theoretic security in an incomplete
  network of reliable\, private links.\nSeparate characterizations are obta
 ined for honest-but-curious and malicious modes of corruption with securit
 y against general adversary structures.\n- Many cryptographic tasks can be
  modelled as secure 2-party computation (2PC) using only one-directional c
 ommunication.\nGarg et al. (Crypto 15) initiated the study of non-interact
 ive 2PC over noisy channels with one-way communication\, namely when only 
 one party speaks.\nA major question left open by that work was the complet
 eness of finite channels in this model of secure computation.\nWe show tha
 t bit-ROT (i.e.\, Randomized Oblivious Transfer) channel\, which erases on
 e of the two input bits uniformly at random\, can compute any functionalit
 y with inverse polynomial security error (in the number of channel uses) i
 n this model against a computationally unbounded adversary.\nFurther\, ass
 uming ideal obfuscation\, realizable using tamper-proof hardware tokens\, 
 naturally occurring channels such as binary symmetric channel (BSC) and bi
 nary erasure channel (BEC) are complete in this sense with inverse polynom
 ial security error against a computationally bounded adversary.\nTo comple
 ment this\, we show that no channel with finite alphabet is complete in th
 is model with negligible security error even against a computationally bou
 nded adversary.\nFinally\, we characterize the channels that enable zero-k
 nowledge proofs in this model\; the previous result work had presented con
 struction of zero-knowledge proofs using BEC/BSC channels.\n- Studying sec
 ure computation with limited interaction tends to reveal new frontiers to 
 approach the problem of complexity of several information theoretic primit
 ives: a notoriously hard problem in cryptography.\nWe introduce a new prim
 itive in information-theoretic cryptography\, namely zero-communication re
 ductions (ZCR)\, with varying levels of security\, and relate it with many
  other important primitives.\nUsing these connections\, we obtain new uppe
 r bounds and lower bounds for complexity of these cryptographic primitives
 .\n- MPC provides a meaningful and robust definition of security that can 
 be used for modelling security guarantees for existing models in network i
 nformation theory.\nIndex coding is a well studied problem in which a serv
 er wants to efficiently broadcast n messages intended for n users\, each w
 ith access to a subset of these messages as side information.\nWe introduc
 e a notion of privacy in index coding\, where the receivers do not learn a
 nything more than the message they want from the server and those they hav
 e as side information\, and study various aspects of its transmission rate
  and secret consumption rate.\n\nJoin Zoom Meeting\nhttps://zoom.us/j/9507
 4700581?pwd=dWVWZ0Y0WFVETGJYeDExRXJoN3BuQT09\nMeeting ID: 950 7470 0581\nP
 asscode: 384118\n
URL:https://www.tcs.tifr.res.in/web/events/1176
DTSTART;TZID=Asia/Kolkata:20211207T173000
DTEND;TZID=Asia/Kolkata:20211207T183000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1177
DTSTAMP:20230914T125953Z
SUMMARY:Exact Sampling and List-Decoding
DESCRIPTION:Speaker: Siddharth Bhandari\n\nAbstract: \nIn this thesis defen
 se\, we will discuss the following results.\n1.  Exact sampling:  We wil
 l present an efficient algorithm that\, given a graph of maximum degree $\
 \Delta$ and a list of at least $3\\Delta+1$ colours\, produces a random co
 louring of the graph that is \\emph{exactly} uniformly distributed on the 
 set of all proper colourings.  Before this work\, it was known that exact
  sampling was possible if about $\\Delta^2$ colours were allowed.\n2. List
 -decoding error-correcting codes:  In list-decoding\, the decoder\, based
  on the received word\, is required to output a small list of messages\, o
 ne of which must be the original message. We will discuss the following re
 sults about list-decoding.\n(a) Zero-error list decoding capacity of the $
 q/(q-1)$ channel:  We will present a lower bound showing that the zero-er
 ror list decoding capacity of this channel is exponentially small in $q$ e
 ven if the list size is allowed grow as $\\frac{1}{6} q \\ln q$. Previous 
 results showed that the capacity was exponentially small if the list size 
 was allowed to grow no larger than $1.58q$.\n(b) Multiplicity codes:  We 
 consider a  natural generalization of Reed-Muller codes where at each eva
 luation point\,  one records not only the evaluation of the message polyn
 omial\, but also all its partial derivatives up to a certain order. We wil
 l present an efficient algorithm that (under mild assumptions)  list-deco
 des multivariate multiplicity codes on arbitrary grids up to their distanc
 e.  Previously such results were known only for univariate multiplicity c
 odes.\n(c) Polynomial ideal codes:  A polynomial ideal code is specified 
 by a collection of relatively prime monic polynomials. The encoding is obt
 ained by specifying the remainders of the message polynomial modulo the va
 rious polynomials in the collection. We will describe an efficient algorit
 hm to list-decode some special polynomial ideal codes\, which we \\emph{ca
 ll affine folded Reed-Solomon codes\,} up to their distance. Previous resu
 lts allowed list-decoding up to the distance for folded Reed-Solomon codes
 \, univariate multiplicity codes and additive folded Reed-Solomon codes\, 
 which are all instances of affine folded Reed-Solomon codes.\n(The above r
 esults were obtained in collaborations that involved the\nfollowing: Sayan
 tan Chakraborty\, Prahladh Harsha\, Mrinal Kumar\, Jaikumar Radhakrishnan\
 , Madhu Sudan.)\n\nZoom link: https://zoom.us/j/95587295066?pwd=ZW5QQ1NrSV
 EwOG5iZzloVTlMV2ZBZz09\n
URL:https://www.tcs.tifr.res.in/web/events/1177
DTSTART;TZID=Asia/Kolkata:20211210T090000
DTEND;TZID=Asia/Kolkata:20211210T100000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1178
DTSTAMP:20230914T125953Z
SUMMARY:Convergence of nearest neighbor classification
DESCRIPTION:Speaker: Sanjoy Dasgupta (UC San Diego Jacobs School of Enginee
 ring\nSan Diego\, California.)\n\nAbstract: \nThe "nearest neighbor (NN) c
 lassifier" labels a new data instance by taking a majority vote over the k
  most similar instances seen in the past. With an appropriate setting of k
 \, it is capable of modeling arbitrary decision rules.\nTraditional conver
 gence analysis for nearest neighbor\, as well as other nonparametric estim
 ators\, has focused on two questions: (1) universal consistency---that is\
 , convergence (as the number of data points goes to infinity) to the best-
 possible classifier without any conditions on the data-generating distribu
 tion---and (2) rates of convergence that are minimax-optimal\, assuming th
 at data distribution lies within some standard class of smooth functions.\
 nWe advance what is known on both these fronts. But we also show how to at
 tain significantly stronger types of results: (3) rates of convergence tha
 t are accurate for the specific data distribution\, rather than being gene
 ric for a smoothness class\, and (4) rates that are accurate for the distr
 ibution as well as the specific query point.\nAlong the way\, we introduce
  a notion of "margin" for nearest neighbor classification. This is a funct
 ion m(x) that assigns a positive real number to every point in the input s
 pace\; and the size of the data set needed for NN (with adaptive choice of
  k) to predict correctly at x is\, roughly\, 1/m(x).\nThe statistical back
 ground needed for understanding these results is minimal\, and will be int
 roduced during the talk.\nThis is joint work with Akshay Balsubramani\, Ka
 malika Chaudhuri\, Yoav Freund\, and Shay Moran.\nBio:\nSanjoy Dasgupta wo
 rks on unsupervised and minimally supervised learning. He is a professor o
 f computer science at UC San Diego.\nYouTube livestream: https://www.youtu
 be.com/watch?v=NMrPyN2neaw\n
URL:https://www.tcs.tifr.res.in/web/events/1178
DTSTART;TZID=Asia/Kolkata:20220111T103000
DTEND;TZID=Asia/Kolkata:20220111T113000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1179
DTSTAMP:20230914T125953Z
SUMMARY:Fourier Analytic Techniques in Machine Learning
DESCRIPTION:Speaker: Somnath Chakraborty\n\nAbstract: \nIn this talk\, we w
 ill discuss the following two problems.\n \nProblem 1. Given independent r
 andom samples drawn from an (almost uniform) mixture of at most k spherica
 l d-dimensional Gaussians of unit variance\, can we devise an efficient al
 gorithm that recovers the center's within arbitrary accuracy?\n\nProblem 2
 . How can we integrate in the class of Lipschitz functions on d-dimensiona
 l sphere\, computationally efficiently?\n\nEfficient algorithms are known 
 to deal with the first problem in the constant dimensions. We show that in
  the regime d= log k\, Fourier analytic ideas can be employed to obtain an
  efficient algorithm\, provided that minimum separation of the center's of
  the individual Gaussian components is O(✓d). This minimum separation is
  known to be optimal.\n\nFor the second problem\, we find a computationall
 y efficient method of finding an equidistributed net on a d-dimensional sp
 here. The techniques are inspired by work of Landau-Russell (2004) which u
 sed ideas from Fourier analysis on finite groups to get a quantitative imp
 rovement on the Alon-Roichman theorem that says a random Cayley graph is a
 n expander.\n\nThese results are based on joint work with Hariharan Naraya
 nan.\n\nJoin Zoom Meeting\nhttps://zoom.us/j/97251350514?pwd=UVA5aTR4eFlZT
 VpER2dFRnZoRXJDUT09\n\nMeeting ID: 972 5135 0514\nPasscode: 844383\n
URL:https://www.tcs.tifr.res.in/web/events/1179
DTSTART;TZID=Asia/Kolkata:20220112T090000
DTEND;TZID=Asia/Kolkata:20220112T100000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1180
DTSTAMP:20230914T125953Z
SUMMARY:Stochastic window mean-payoff games
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nWe consider two-player sto
 chastic games on a graph. Two-player stochastic games are a generalization
  of  two-player games and Markov decision processes. Each state in the gr
 aph is controlled by one of the two players P1 and P2. The game begins by 
 placing a token on the initial state. In each turn\, the player controllin
 g the state of the token chooses an action\, which then returns a probabil
 ity distribution over the out-edges from the state. An out-edge is chosen 
 according to this distribution\, the token is moved along this edge to a n
 ew state\, and the turn ends. The game then starts from the new state\, an
 d the player who controls this new state chooses an action available from 
 that state.\nThis continues ad infinitum.\nIn this work\, we consider wind
 ow mean-payoff objective. Each edge has a rational payoff. The sequence of
  edges chosen in a play corresponds to a sequence of payoffs. Given an int
 eger l\, and a threshold \\lambda\, the objective of player P1 is to ensur
 e that from every state in a play\, for some interval window of length at 
 most l\, the mean of the payoffs in the window is at least \\lambda. The o
 bjective of player P2 is the complement of P1's objective. Window mean-pay
 off objectives have been studied for two-player games and for Markov decis
 ion processes earlier. We study here two-player stochastic games with wind
 ow objectives.\n\nZoom Meeting link:\nhttps://zoom.us/j/96361358353?pwd=U2
 92aStIb3h5M1FIUTZWYThaL2dDdz09\nMeeting ID: 963 6135 8353\nPasscode: 70301
 4\n
URL:https://www.tcs.tifr.res.in/web/events/1180
DTSTART;TZID=Asia/Kolkata:20220118T110000
DTEND;TZID=Asia/Kolkata:20220118T120000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1181
DTSTAMP:20230914T125953Z
SUMMARY:Designing Service Menus for Bipartite Queueing Systems
DESCRIPTION:Speaker: Varun Gupta (University of Chicago)\n\nAbstract: \nWe 
 look at the problem of designing a matching system with queues in an envir
 onment with multiple types of customers and multiple classes of servers. C
 ustomers arrive to the system seeking service by one of many available ser
 vers\, and the reward or value obtained by a customer depends on both the 
 customer's type as well as the class of server which services the customer
 . The goal of the system designer is to design a service mechanism that wi
 ll match customers to servers and balance the two (usually) competing obje
 ctives: (1) maximize customers' average service reward and (2) minimize cu
 stomers' average waiting time delay. We restrict ourselves to a special cl
 ass of mechanisms in which the system designer offers a static menu of ser
 vice classes and customers choose which one of them to join upon arrival. 
 A service class is defined by a single queue served by a specific subset o
 f servers under a First-Come-First-Served (FCFS) service discipline. Custo
 mers act as rational self-interested utility maximizing agents when choosi
 ng which service class to join. We study the problem under (conventional) 
 heavy traffic conditions\, that is\, in the limit as the traffic intensity
  of the system approaches one from below\, and provide insights into the d
 esign tradeoffs of "good" service menus.\nThe talk will be based on a work
 -in-progress with Lisa Hillas and Rene Caldentey\, and the following paper
  with Philipp Afeche and Rene Caldentey (https://papers.ssrn.com/sol3/pape
 rs.cfm?abstract_id=3345302).\nBio: Varun Gupta studies stochastic modeling
  and optimization\, applied probability\, algorithm design and analysis\, 
 and mechanism design. He is particularly interested in modeling and optimi
 zation of resource allocation policies for multi-server and distributed sy
 stems (e.g.\, third party logistics\, cloud infrastructure\, health care) 
 from a queueing theoretic perspective\, and learning and control in non-st
 ationary environments.\nGupta holds a PhD in computer science from Carnegi
 e Mellon University. He completed his undergraduate studies in computer sc
 ience and engineering at the Indian Institute of Technology in Delhi where
  he was awarded the President's Gold Medal. Outside of academia Varun has 
 spent time in industry at Alcatel-Lucent Bell Laboratories\, Microsoft Res
 earch\, and Google Research.\n
URL:https://www.tcs.tifr.res.in/web/events/1181
DTSTART;TZID=Asia/Kolkata:20220118T183000
DTEND;TZID=Asia/Kolkata:20220118T193000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1182
DTSTAMP:20230921T105045Z
SUMMARY:A peek into Meta-Complexity
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nMeta-complexity refers
  to the study of complexity of problems that are themselves about computat
 ional complexity. The canonical meta-complexity problem in the Boolean wor
 ld is MCSP (Minimum Circuit Size Problem). A recent result by Ilango has s
 hone some light on when one can get an efficient Search-to-Decision reduct
 ion for MFSP\, a variant of MCSP for formulas instead of circuits. We stud
 ied their result in hopes of importing it to similar problems in the algeb
 raic world. On the way\, we simplified a lemma from their paper and also o
 bserved a surprising behaviour of random Boolean formulas\; these will be 
 the contents of this project seminar.\n
URL:https://www.tcs.tifr.res.in/web/events/1182
DTSTART;TZID=Asia/Kolkata:20220119T110000
DTEND;TZID=Asia/Kolkata:20220119T120000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1183
DTSTAMP:20230914T125953Z
SUMMARY:Lower bound on randomness complexity of secure computations of AND
DESCRIPTION:Speaker: Hari Krishnan P A\n\nAbstract: \nIn a secure multi-par
 ty computation problem\, players are required to compute a function of the
 ir private inputs without revealing any extra information about this input
  to other players. Randomness complexity is the number of random bits used
  by the protocol which enables such a computation. Since randomness is an 
 expensive resource\, developing MPC protocols to operate on minimum amount
  of randomness has been an interesting problem. In a recent work\, Kushile
 vitz et. al. prove a lower bound of 1 bit and an upper bound of 7 bits (8 
 bits) for the randomness complexity of securely computing Boolean AND func
 tion in a 3-player (n>3 player) setting. In this work\, we improve upon th
 is lower bound obtaining 3 bits for a 3-player setting using information t
 heoretic tools.\nZoom link -\nhttps://zoom.us/j/98392241202?pwd=bTJRYklZZE
 RXWWpIK0RIdnFZNzJSQT09\n
URL:https://www.tcs.tifr.res.in/web/events/1183
DTSTART;TZID=Asia/Kolkata:20220124T160000
DTEND;TZID=Asia/Kolkata:20220124T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1184
DTSTAMP:20230914T125953Z
SUMMARY:Sequential Hypothesis Testing under Stochastic Deadlines
DESCRIPTION:Speaker: Sushant Vijayan\n\nAbstract: \nPaper by: Peter Frazier
  and Angela Yu (NIPS 2007).\nThe paper presents a generalisation to the cl
 assic Wald-Wolfowitz result in the sequential hypothesis setting. They mod
 ify the problem to incorporate stochastic deadlines and incorporate a more
  general loss function. The paper solves the problem using dynamic program
 ming techniques under a bayesian setting. I intend to talk a little bit ab
 out the Wald-Wolfowitz solution and then discuss the paper.\n\nZoom link:\
 nhttps://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1184
DTSTART;TZID=Asia/Kolkata:20220128T171500
DTEND;TZID=Asia/Kolkata:20220128T181500
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1185
DTSTAMP:20230914T125953Z
SUMMARY:A Study of Information Transmission over Quantum Channels in the On
 e Shot Setting
DESCRIPTION:Speaker: Sayantan  Chakraborty\n\nAbstract: \nWe study informat
 ion transmission over quantum channels in the one shot setting. We primari
 ly consider multiterminal channels and develop several tools to send quant
 um information over these channels.\nOur first contribution is a generalis
 ation of the well known decoupling theorem\, to the setting of multiple se
 nders\, which immediately allows us to design encoders and decoders for en
 tanglement transmission over the quantum multiple access channel\, among o
 ther applications. However\, these results are non-smooth\, in the sense t
 hat they do not recover the best known asymptotic iid bounds.\nTo overcome
  this issue\, we develop two new techniques which we believe will be usefu
 l in other contexts as well \;\ni. Successive cancellation decoding for en
 tanglement transmission codes\nii. Quantum Rate Splitting\nFinally\, we ta
 ckle the problem of sending private classical information over the quantum
  MAC in the presence of an eavesdropper. Nothing was known about this prob
 lem\, even in the asymptotic iid setting\, due to a famous open problem th
 at becomes a bottleneck for most coding strategies. This problem is known 
 as 'simultaneous smoothing'. We overcome this issue by developing a new su
 ccessive cancellation covering lemma\, which allows us to recover the idea
 l rate region in the asymptotic iid setting. We also recover a non-trivial
  rate region in the one shot setting by using our new covering lemma in co
 njunction with our quantum rate splitting technique\n
URL:https://www.tcs.tifr.res.in/web/events/1185
DTSTART;TZID=Asia/Kolkata:20220201T140000
DTEND;TZID=Asia/Kolkata:20220201T150000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1186
DTSTAMP:20230914T125953Z
SUMMARY:Different flavours of differential privacy
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nDifferential privacy (DP) 
 gives a rigorous framework for data privacy by giving guarantees on the in
 formation leakage for individual data points from the output of an algorit
 hm. However\, DP has a somewhat paranoid view of the world which might be 
 too demanding for certain applications.\n\nIn this talk\, we shall first l
 ook at some relaxations of DP - in particular R\\'enyi differential privac
 y (RDP). One of the strengths of RDP is that it preserves the composition 
 properties of DP\, i.e. it is easy to bound the privacy loss of a sequence
  of RDP mechanisms.\n\nThen\, we will do a quick overview of local differe
 ntial privacy (LDP) - a notion of privacy useful for distributed applicati
 ons. Time permitting\, we will also see how differential privacy is relate
 d to generalization.\n\nZoom link:\nhttps://zoom.us/j/93889521556?pwd=eEFJ
 WVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1186
DTSTART;TZID=Asia/Kolkata:20220204T160000
DTEND;TZID=Asia/Kolkata:20220204T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1187
DTSTAMP:20230914T125953Z
SUMMARY:Applying physics to mathematics
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nThis talk is based on Tada
 shi Tokieda's wonderful talk (https://www.youtube.com/watchv=tQQ3oiB32GI&t
 =1s) as a part of ICTS's distinguished lecture series. To quote Tokeida\, 
 "Humans tend to be better at physics than at mathematics. When an apple fa
 lls from a tree\, there are more people who can catch it—we know physica
 lly how the apple moves—than people who can compute its trajectory from 
 a differential equation. Applying physical ideas to discover and establish
  mathematical results is therefore natural\, even if it has seldom been tr
 ied in the history of science."\n\nWe will see how we can derive fundament
 al theorems like Pythagoras theorem\, Cauchy-Schwarz inequality\, AM-GM in
 equality among others using simple physics.\n\nZoom link:\nhttps://zoom.us
 /j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1187
DTSTART;TZID=Asia/Kolkata:20220211T160000
DTEND;TZID=Asia/Kolkata:20220211T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1188
DTSTAMP:20230914T125954Z
SUMMARY:Fano's method for lower bounds in machine learning
DESCRIPTION:Speaker: Neha Sangwan\n\nAbstract: \nWe will see how Fano's ine
 quality\, a classical result from information theory\, can be used to get 
 tight lower bounds on sample complexity of various learning problems. We w
 ill derive Fano's inequality and see its application on an example problem
 .\n\nZoom link: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJG
 QTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1188
DTSTART;TZID=Asia/Kolkata:20220218T160000
DTEND;TZID=Asia/Kolkata:20220218T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1189
DTSTAMP:20230914T125954Z
SUMMARY:Extension Preservation in the Finite and Prefix Classes of First Or
 der Logic
DESCRIPTION:Speaker: Abhisekh Sankaran (University of Cambridge)\n\nAbstrac
 t: \nIt is well known that the classic Los-Tarski preservation theorem fai
 ls in the finite: there are first order definable classes of finite struct
 ures closed under extensions which are not definable in the existential fr
 agment of first order logic. We strengthen this [1] by constructing for ev
 ery n\, first order definable classes of finite structures closed under ex
 tensions which are not definable with n quantifier alternations. The class
 es we construct are definable in the extension of Datalog with negation. T
 his answers negatively an open question posed by Rosen and Weinstein [2].\
 n[1] Anuj Dawar and Abhisekh Sankaran. Extension preservation in the finit
 e and prefix classes of first order logic. Proceedings of the 31st Compute
 r Science Logic (CSL)\, Ljubljana\, Slovenia\, January 25 -- 28\, 2021\, p
 p. 18:1 -- 18:13.\n[2] Eric Rosen and Scott Weinstein. Preservation theore
 ms in finite model theory. In the International Workshop on Logic and Comp
 utational Complexity\, pages 480âEUR"502. Springer\,1994.\n\nBio: Abhisek
 h Sankaran is a post-doctoral research associate at the Department of Comp
 uter Science and Technology of the University of Cambridge\, UK. He works 
 with Prof. Anuj Dawar  and has been at Cambridge since September 2018. Pri
 or to that\, he was a post-doctoral fellow for a year in the Theoretical C
 omputer Science Wing of the Institute of Mathematical Sciences Chennai. He
  completed his Ph.D. and also his Bachelors and Masters from the Computer 
 Science department of IIT Bombay. His research interests lie in mathematic
 al logic\, particularly classical and finite model theory\, and parameteri
 zed algorithms\, particularly algorithmic metatheorems. For the present se
 minar\, he will be  speaking on a classical model theoretic result in the 
 context of finite structures.\n
URL:https://www.tcs.tifr.res.in/web/events/1189
DTSTART;TZID=Asia/Kolkata:20220222T160000
DTEND;TZID=Asia/Kolkata:20220222T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1190
DTSTAMP:20230914T125954Z
SUMMARY:Measurement Compression
DESCRIPTION:Speaker: Sayantan  Chakraborty\n\nAbstract: \nOne of the fundam
 ental components of quantum theory is measurement. one can think of measur
 ement as the interface between the quantum world and our everyday world. A
 n experimenter can gather information about a quantum state by doing measu
 rements on it and use this information to design quantum protocols. Measur
 ement\, however\, is a noisy process. The noise can arise from the measure
 ment apparatus itself or from the uncertainty inherent in the quantum stat
 e in this talk we will try to understand how one can separate out these tw
 o types of noise. One can do this by formulating an information processing
  task called measurement compression.\n\nMeasurement compression was first
  proposed by Winter and subsequently generalised further by Wilde et al. H
 owever the original proofs of this protocol are extremely complicated. The
  talk will be based on new work by Chakraborty\, Padakandla and Sen by whi
 ch we can obtain a much more elementary understanding of this fundamental 
 information processing task.\n\nZoom link: https://zoom.us/j/93889521556?p
 wd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1190
DTSTART;TZID=Asia/Kolkata:20220225T160000
DTEND;TZID=Asia/Kolkata:20220225T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1191
DTSTAMP:20230914T125954Z
SUMMARY:Reconfiguring Shortest Paths in Graphs
DESCRIPTION:Speaker: Kshitij Gajjar (National University of Singapore)\n\nA
 bstract: \nReconfiguring a system (generally represented by a graph) means
  gradually transforming one configuration of the system to another configu
 ration by modifying it in a slow and steady step-by-step manner. In the Sh
 ortest Path Reconfiguration (SPR) problem\, we are given two shortest path
 s\, and the goal is to transform one shortest path to the other by changin
 g one vertex at a time\, so that all the intermediate configurations are a
 lso shortest paths. SPR has many real-world applications like repaving roa
 ds in a systematic way\, rerouting messages across a network of telecommun
 ication towers\, cargo container stowage on ships\, train marshalling\, an
 d rerouting data packets across servers in a synchronous multiprocessor se
 tting.\n\nIn this talk\, we will show how one of these applications can be
  modelled by a specific class of graphs\, and then we will solve SPR for t
 hat graph class. We will also show that if we are allowed to change two ve
 rtices at a time\, then SPR becomes PSPACE-complete\, even for a graph cla
 ss for which SPR is known to be solvable in polynomial time when we are al
 lowed to change only one vertex at a time. This is joint work with Agastya
  Vibhuti Jha\, Manish Kumar and Abhiruk Lahiri (https://arxiv.org/abs/2112
 .07499).\nZoom link: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmh
 NYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1191
DTSTART;TZID=Asia/Kolkata:20220304T161500
DTEND;TZID=Asia/Kolkata:20220304T171500
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1192
DTSTAMP:20230914T125954Z
SUMMARY:Spectral Methods in Modern Graph Algorithms
DESCRIPTION:Speaker: Akash Kumar (EPFL\, Lausanne\, CH)\n\nAbstract: \nSpec
 tral methods have had a strong influence on modern graph algorithms as evi
 denced by the extensive literature on the subject. In my research so far\,
  I have used spectral methods to develop algorithms for problems on planar
  graphs\, and to develop algorithms to recover planted subgraphs in an oth
 erwise gigantic random graph.\nIn this talk\, I will focus on my contribut
 ions towards algorithmic problems on planar graphs. In particular\, I show
  how random walk based (i.e.\, spectral) approaches led to progress on fin
 ding forbidden minors [K.-Seshadhri-Stoman\, FOCS 2018] as well as on deci
 ding planarity [K.-Seshadhri-Stolman\, STOC 2019] in bounded degree graphs
  within the property testing framework. I will also cover how these approa
 ches eventually led to progress on the so-called "efficient partition orac
 le" problem [K.-Seshadhri-Stolman\, FOCS 2021].\nBio: Akash Kumar is a pos
 tdoc at EPFL (Switzerland). His research interests lie in spectral graph t
 heory and property testing. Before starting his postdoctoral position\, he
  completed his PhD from Purdue University (USA) in May 2020 under the supe
 rvision of Saugata Basu.\n\nJoin Zoom Meeting\nhttps://zoom.us/j/997106870
 41?pwd=eHRvT1Y3OFJYMFk1QXNnVnFvMXZvUT09\nMeeting ID: 997 1068 7041\nPassco
 de: 543679\n
URL:https://www.tcs.tifr.res.in/web/events/1192
DTSTART;TZID=Asia/Kolkata:20220308T160000
DTEND;TZID=Asia/Kolkata:20220308T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1193
DTSTAMP:20230914T125954Z
SUMMARY:Further Collapses in TFNP
DESCRIPTION:Speaker: Siddhartha Jain (EPFL\, Switzerland)\n\nAbstract: \nWe
  show EOPL=PLS PPAD. Here the class EOPL consists of all total search prob
 lems that reduce to the End-of-Potential-Line problem\, which was introduc
 ed in the works by Hubacek and Yogev (SICOMP 2020) and Fearnley et al. (JC
 SS 2020). In particular\, our result yields a new simpler proof of the bre
 akthrough collapse CLS=PLS PPAD by Fearnley et al. (STOC 2021). We also pr
 ove a companion result SOPL=PLS PPADS\, where SOPL is the class associated
  with the Sink-of-Potential-Line problem.\n\nThe talk will be based on the
  following paper: https://eccc.weizmann.ac.il/report/2022/018/\n\nZoom lin
 k: https://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz09\n
URL:https://www.tcs.tifr.res.in/web/events/1193
DTSTART;TZID=Asia/Kolkata:20220311T161500
DTEND;TZID=Asia/Kolkata:20220311T171500
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1194
DTSTAMP:20230914T125954Z
SUMMARY:Hardness and Independence of Polynomials
DESCRIPTION:Speaker: Prerona  Chatterjee\n\nAbstract: \nAlgebraic Complexit
 y Theory is a field in which one studies complexity theoretic questions su
 rrounding algebraic objects. In this talk we will be broadly discussing tw
 o such problems.\nThe first problem is showing lower bounds for explicit p
 olynomials against various algebraic computational models. The most natura
 l and well studied models of computation are algebraic circuits\, algebrai
 c branching programs (ABPs) and algebraic formulas. With respect to provin
 g lower bounds against these models\, we show the following results.\n1. A
 ny algebraic branching program computing \\sum_{i=1}^n x_i^n must have at 
 least n^2 vertices. The previous best known lower bound was \\Omega(n log 
 n) on the number of edges for the same polynomial [Baur-Strassen].\n2. Any
  formula computing the elementary symmetric polynomial of degree 0.1n must
  have at least n^2 vertices. The previous best lower bound for any multili
 near polynomial was \\Omega(n^2/log n) [Nechiporuk\, Kalorkoti]. It can al
 so be shown that previous known methods can not prove a bound better than 
 \\Omega(n^2/log n) for any explicit multilinear polynomial.\nThis is joint
  work with Mrinal Kumar\, Adrian She and Ben Lee Volk.\nAlong with proving
  lower bounds against these models\, studying their relative powers is als
 o an important problem in algebraic circuit complexity. It is known that f
 ormulas can be efficiently simulated by ABPs and checking whether the conv
 erse of this statement holds is a central question in the field. We make p
 rogress towards solving this problem in the non-commutative setting\, wher
 e we show a tight super-polynomial separation between ABPs and some struct
 ured formulas.\nThe second problem that we are interested in relates the q
 uestions of checking whether a given algebraic compuational model is compu
 ting the zero polynomial or not and checking whether a given set of polyno
 mials is algebraically independent or not. The connection between these qu
 estions is via the notion of Faithful Homomorphisms. Although construction
  of faithful homomorphisms were known when the underlying field had charac
 teristic zero [Beecken-Mittman-Saxena\, Agrawal-Saha-Saptharishi-Saxena]\,
  they were not known in the setting where the underlying field had finite 
 characteristic since efficient algorithms to check algebraic indepndence w
 ere not known in this setting. Following up on the work of Pandey\, Saxena
  and  Sinhababu\, we construct faithful homomorphisms over fields of fini
 te characetristics in some restricted settings and as a consequence show e
 fficient polynomial identity tests for related models of computation. This
  is joint work with Ramprasad Saptharishi.\n
URL:https://www.tcs.tifr.res.in/web/events/1194
DTSTART;TZID=Asia/Kolkata:20220317T143000
DTEND;TZID=Asia/Kolkata:20220317T153000
LOCATION:in person @ R.No. AG-66 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1195
DTSTAMP:20230914T125954Z
SUMMARY:Determinacy of Two-Player Games with Perfect Information
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nA game with *perfect infor
 mation* is a game in which no information is hidden from the players. All 
 players know the rules and the state of the game at all times. Some exampl
 es of games with perfect information are Chess\, Checkers\, Go\, and Nim.\
 nIn two-player zero-sum games\, a player has a *winning strategy* if they 
 can always win no matter how the other player plays. A game is\n*determine
 d* if one of the players has a winning strategy. Given a two-player game w
 ith perfect information\, we would like to find out if it is determined.\n
 In today's talk\, we discuss some results on two-player games with perfect
  information:\n- We show that all finite games are determined.\n- We const
 ruct an example of an infinite game that is not determined.\n- We define a
  topology on infinite games. We use this to show the determinacy of some s
 pecial classes of infinite games.\nAll results are from:\n[1] "Theory of G
 ames and Economic Behavior" by von Neumann and Morgenstern\, 1947.\n[2] "I
 nfinite Games with Perfect Information" by Gale and Stewart\, 1953.\n\nZoo
 m link:\nhttps://zoom.us/j/93889521556?pwd=eEFJWVRtRHNpNlpZWmhNYTJGQTF6Zz0
 9\n
URL:https://www.tcs.tifr.res.in/web/events/1195
DTSTART;TZID=Asia/Kolkata:20220325T161500
DTEND;TZID=Asia/Kolkata:20220325T171500
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1196
DTSTAMP:20230914T125954Z
SUMMARY:Context-Bounded Verification of Multithreaded Shared Memory Program
 s
DESCRIPTION:Speaker: Ramanathan Thinniyam (Max Planck Institute for Softwar
 e Systems)\n\nAbstract: \nMultithreaded shared memory programs appear in m
 any applications such as operating systems\, web servers\, mobile applicat
 ions etc. Verification of such programs has been of increasing concern sin
 ce the early 2000s when clock speeds stabilised\, with the focus shifting 
 to architectures with multiple cores. From a theoretical perspective\, any
  problem is undecidable already for programs with just two recursive threa
 ds since one can then simulate a Turing machine. Hence we focus on restric
 ting the problems to runs of the program which are context-bounded i.e. wh
 ere every thread can be active at most K many times for some fixed number 
 K. This restriction has been effective at finding bugs since from a practi
 cal standpoint most bugs occur already with a low number of context switch
 es. We resolve long standing open problems related to the complexity of sa
 fety and liveness verification of multithreaded programs in the presence o
 f context bounding. This talk is aimed at giving a high level overview of 
 these results.\nBio: Ramanathan Thinniyam is currently a postdoc at the Ma
 x Planck Institute for Software Systems in the Rigorous Software Engineeri
 ng group. He obtained his BTech in Mechanical Engineering in IIT Madras\, 
 MSc in Theoretical Computer Science(TCS) at CMI and PhD in TCS at IMSc.\nH
 e has been working on theoretical aspects of verification of multithreaded
  programs and has published in conferences such as ICALP\, POPL and TACAS.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1196
DTSTART;TZID=Asia/Kolkata:20220405T160000
DTEND;TZID=Asia/Kolkata:20220405T170000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1197
DTSTAMP:20230914T125954Z
SUMMARY:Sketching and Streaming Complexity of Constraint Satisfaction Probl
 ems
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Paulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nIn this talk we will describe so
 me of our recent work giving new upper and lower bounds on the approximabi
 lity of constraint satisfaction problems (CSPs) in the streaming and sketc
 hing settings. (Streaming algorithms process the input with small space\, 
 while sketching algorithms are restricted streaming algorithms that have a
 dditional composability requirements.) When the sketching algorithms are c
 onstrained to sub-polynomial space in the input length we get a fine dicho
 tomy: CSPs on n variables are either solvable in polylogarithmic space or 
 require at least sqrt(n) space. Our positive results show the broad applic
 ability of what we call ``bias-based sketching algorithms''\, and our nega
 tive results work by abstracting and significantly generalizing previous b
 ounds for the Maximum Cut problem. We will also mention some partial exten
 sions to streaming algorithms\, linear space lower bounds\, ordering CSPs.
 \nBased on joint work with Chi-Ning Chou\, Sasha Golovnev and Santhoshini 
 Velusamy.\n
URL:https://www.tcs.tifr.res.in/web/events/1197
DTSTART;TZID=Asia/Kolkata:20220408T100000
DTEND;TZID=Asia/Kolkata:20220408T110000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1198
DTSTAMP:20230914T125954Z
SUMMARY:An Algorithmic Approach to Uniform Lower Bound Conjectures
DESCRIPTION:Speaker: Rahul Santhanam (Department of Computer Science\nUnive
 rsity of Oxford)\n\nAbstract: \nWe describe an algorithmic approach to uni
 form lower bound conjectures such as NP != P and PSPACE != P.\n
URL:https://www.tcs.tifr.res.in/web/events/1198
DTSTART;TZID=Asia/Kolkata:20220408T160000
DTEND;TZID=Asia/Kolkata:20220408T170000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1199
DTSTAMP:20230914T125954Z
SUMMARY:Improved Quantum Query Upper Bounds Based on Classical Decision Tre
 es
DESCRIPTION:Speaker: Nikhil S. Mande (CWI\, Amsterdam.)\n\nAbstract: \nIn t
 he first part of this talk we will discuss the notion of rank of decision 
 trees\, which is essentially the largest depth of a complete subtree embed
 ded in the initial tree. We observe the equivalence of rank and "guessing 
 complexity\," a measure of decision trees used by Lin and Lin [Theory of C
 omputing'16] and Beigi and Taghavi [Quantum'20] to give upper bounds on qu
 antum query complexity of functions based on classical query algorithms fo
 r them.\n\nIn the second part of the talk we will first note that the best
  speed-up obtainable using the approach of Beigi and Taghavi is captured b
 y a polynomial optimization program on assignments of real weights to edge
 s of the underlying classical decision tree. We then give a recursive expr
 ession for the optimal solution to this program and bound the optimum from
  above in terms of natural measures of the decision tree.\n\nBased on join
 t work with Arjan Cornelissen and Subhasree Patro (https://arxiv.org/abs/2
 203.02968).\n
URL:https://www.tcs.tifr.res.in/web/events/1199
DTSTART;TZID=Asia/Kolkata:20220426T160000
DTEND;TZID=Asia/Kolkata:20220426T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1200
DTSTAMP:20230914T125954Z
SUMMARY:Power-laws and weak convergence of the Kingman coalescent
DESCRIPTION:Speaker: Henrik Hult (KTH Royal Institute of Technology)\n\nAbs
 tract: \nThe Kingman coalescent is an important and well-studied process i
 n population genetics modelling the ancestry of a sample of individuals. I
 n this talk weak convergence results are presented that characterise asymp
 totic properties of the Kingman coalescent under parent dependent mutation
 s\, as the sample size grows to infinity. It is shown that the sampling pr
 obability satisfies a power-law and we derive the asymptotic behaviour of 
 transition probabilities of the block counting jump chain. For the normali
 sed jump chain and number of mutations between types a limiting process is
  derived consisting of a deterministic component\, describing the limit of
  the block counting jump chain\, and independent Poisson processes with st
 ate-dependent intensities\, exploding at the origin\, describing the limit
  of the number of mutations. Finally\, the results are extended to charact
 erise the asymptotic performance of popular importance sampling algorithms
 \, such as the Griffiths-Tavare algorithm and the Stephens-Donnelly algori
 thm. This is joint work with Martina Favero.\n
URL:https://www.tcs.tifr.res.in/web/events/1200
DTSTART;TZID=Asia/Kolkata:20220429T160000
DTEND;TZID=Asia/Kolkata:20220429T170000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1201
DTSTAMP:20230914T125954Z
SUMMARY:Shift\, scale and restart smaller models to estimate larger ones: A
 gent based simulators in epidemiology
DESCRIPTION:Speaker: Daksh Mittal (TIFR Mumbai)\n\nAbstract: \nAgent-based 
 simulators are a popular epidemiological modelling tool to study the impac
 t of various non-pharmaceutical interventions in managing an evolving pand
 emic. They provide the flexibility to accurately model a heterogeneous pop
 ulation with time and location varying\, person specific interactions. To 
 accurately model detailed behaviour\, typically each person is separately 
 modelled. This however\, may make computational time prohibitive when the 
 region population is large and when time horizons involved are large.  In
  this talk we review the agent based city simulator developed by IISC-TIFR
  to model Covid epidemic and dig deeper into the underlying probabilistic 
 structure of the simulator (ABS) to arrive at modifications that allow sma
 ller models to give accurate statistics for larger models. We exploit the 
 observations that in the initial disease spread phase\, the starting infec
 tions create a family tree of infected individuals more-or-less independen
 t of the other trees and are modelled well as a multi-type super-critical 
 branching process. Soon after\, once enough people have been infected\, th
 e future evolution of the pandemic is closely approximated by its mean fie
 ld limit with a random starting state. We build upon these insights to dev
 elop a shift\, scale and restart algorithm for the simulator that accurate
 ly evaluates the ABS's performance using a much smaller model. We provide 
 theoretical support for the proposed approach through an asymptotic analys
 is where the population size increases to infinity.\n
URL:https://www.tcs.tifr.res.in/web/events/1201
DTSTART;TZID=Asia/Kolkata:20220506T163000
DTEND;TZID=Asia/Kolkata:20220506T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1202
DTSTAMP:20230914T125954Z
SUMMARY:A Simple Convergence Proof for A Simple Convergence Proof Stochasti
 c Approximation and Applications to Reinforcement Learning
DESCRIPTION:Speaker: M. Vidyasagar (Indian Institute of Technology Hyderaba
 d.)\n\nAbstract: \nSince its invention by Robbins and Monro in 1951\, the 
 stochastic approximation (SA) algorithm has been a widely used tool for fi
 nding solutions of equations\, or minimizing functions\, with noisy measur
 ements. Current methods for proving its convergence make use of the "ODE" 
 method whereby the sample paths of the algorithm are approximated by the t
 rajectories of an associated ODE. This method requires a lot of technicali
 ties. Interestingly\, as far back as 1965\, there was a paper by Gladyshev
  that gave a simple convergence proof based on martingale methods\; howeve
 r\, this proof worked for only a class of problems. In this talk I will co
 mbine martingale methods with a new "converse theorem" for Lyapunov stabil
 ity\, to arrive at a simple proof that works for the same situations where
  the ODE method applies. The advantage of this approach is that it can pot
 entially be applied to several problems in Reinforcement Learning (RL)\, s
 uch as actor-critic learning (which is two time-scale SA)\, or RL with val
 ue approximation (which is SA with projections onto a lower-dimensional su
 bspace). These directions are under investigation.\nZoom Link - https://z
 oom.us/j/91983281364?pwd=Wkl3MHMzWUFiYnVhV1d1U1E3bXhpZz09\n
URL:https://www.tcs.tifr.res.in/web/events/1202
DTSTART;TZID=Asia/Kolkata:20220510T160000
DTEND;TZID=Asia/Kolkata:20220510T170000
LOCATION:In person @ A-201 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1203
DTSTAMP:20230914T125954Z
SUMMARY:Batch Asynchronous Stochastic Approximation and Applications to Tem
 poral Difference Learning
DESCRIPTION:Speaker: M. Vidyasagar (Indian Institute of Technology Hyderaba
 d.)\n\nAbstract: \n(This talk consists of joint work with Prof. Rajeeva L.
  Karandikar) Reinforcement Learning (RL) algorithms such as Temporal Diffe
 rence (TDL) or Q-learning update *just one component* of the value functio
 n (TDL) or the action-value function (Q) at each time step. This is known 
 as asynchronous stochastic approximation. There are two issues with this. 
 First\, many of the "convergence proofs" in the literature are not always 
 correct. Second\, when the dimension of the state space is very high\, lea
 rning requires a huge number of time steps. In effect\, spatial complexity
  is replaced by temporal complexity. A compromise is to update *some but n
 ot all* components of the value\, or the action-value\, function at each t
 ime step. This may be called Batch Asynchronous Stochastic Approximation (
 BASA). In this talk\, I will present a very general framework for proving 
 the convergence of BASA\, which includes both TD learning and Q-learning a
 s special cases\, and also leads to new algorithms with lower complexity.\
 nZoom Link - https://zoom.us/j/94084902566?pwd=KzNpb3NDQnorTWcvUlJvNXA3eH
 lWUT09\n \n
URL:https://www.tcs.tifr.res.in/web/events/1203
DTSTART;TZID=Asia/Kolkata:20220511T110000
DTEND;TZID=Asia/Kolkata:20220511T120000
LOCATION:In person @ A-201 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1204
DTSTAMP:20230914T125954Z
SUMMARY:Hilbert Schmidt Independence Criterion (HSIC)
DESCRIPTION:Speaker: Jatin Batra\n\nAbstract: \nSuppose we have access to $
 n$ empirical observations of two random variables X\,Y and we want to know
  - are X\,Y independent? One way to answer this is to compute empirical ve
 rsions of various statistical quantities like covariance and mutual inform
 ation. However\, because all we have access to is a finite number ($n$) of
  empirical observations\, we might simply get unlucky. Can we guarantee th
 at our test accuracy increases rapidly with $n$? The Hilbert Schmidt Indep
 endence Criterion (HSIC) proposed by Gretton\, Bousquet\, Smola and Scholk
 opft resolves this issue by providing an estimate of dependence that prova
 bly gets more accurate at a $1/\\sqrt{n}$ rate. In this talk\, I will desc
 ribe (following Gretton et al. in http://www.gatsby.ucl.ac.uk/~gretton/pap
 ers/GreBouSmoSch05.pdf) how HSIC arises quite naturally as a kernel invari
 ant version of the covariance estimate and also allude to some later appli
 cations of HSIC.\n
URL:https://www.tcs.tifr.res.in/web/events/1204
DTSTART;TZID=Asia/Kolkata:20220513T160000
DTEND;TZID=Asia/Kolkata:20220513T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1205
DTSTAMP:20230914T125954Z
SUMMARY:Mixing time and expanders
DESCRIPTION:Speaker: Debsoumya Chakrabarti (IBS Discrete Mathematics Group)
 \n\nAbstract: \nIn a graph\, we call a vertex well-mixing if the standard 
 random walk starting from that vertex reaches close to its stationary dist
 ribution fast (say within 'polylogarithmic in the size of the vertex set' 
 steps). Call a graph well-mixing if all of its vertices are well-mixing. C
 all a graph expander if every subset of vertices has a large boundary (in 
 other words\, the cut induced by every bipartition of the vertex set is 'l
 arge'). For graphs\, it is well-known that the properties of being well-mi
 xing and being an expander are equivalent (in a precise quantitative way).
  Extending (in a weak sense) this classical result\, we establish that a r
 egular graph is virtually an expander even if it has only a positive fract
 ion of vertices that are well-mixing. Indeed\, we prove that such a graph 
 becomes an expander after deleting a small number of vertices. As a coroll
 ary\, it shows that such graphs contain long cycles\, which improves a res
 ult of Pak. Furthermore\, we can obtain such a cycle in polynomial time. T
 his talk will be based on joint work with Jaehoon Kim\, Jinha Kim\, Minki 
 Kim\, and Hong Liu.\n\nYoutube link: https://youtu.be/N3XRrb3Bgzo\n
URL:https://www.tcs.tifr.res.in/web/events/1205
DTSTART;TZID=Asia/Kolkata:20220517T160000
DTEND;TZID=Asia/Kolkata:20220517T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1206
DTSTAMP:20230914T125954Z
SUMMARY:Radial projections in vector spaces over finite fields
DESCRIPTION:Speaker: Ben Lund (IBS Discrete Mathematics Group)\n\nAbstract:
  \nSeveral recent papers by authors including Matilla\, Orponen\, Liu\, Sh
 merikin\, and Wang give upper bounds on the Hausdorff dimension of the set
  of points for which the radial projection of a Borel set in a real vector
  space is much smaller than expected. In recent work\, joint with Thang Ph
 am and Vu Thi Huong Thu\, we prove analogs of several of these theorems fo
 r point sets in vector spaces over finite fields. In several cases\, we ar
 e able to prove stronger bounds than the most natural analogs to the known
  theorems in the continuous case. I will discuss these results\, and if ti
 me permits I'll mention a connection to the Erdos and Falconer problems on
  distinct distances.\n
URL:https://www.tcs.tifr.res.in/web/events/1206
DTSTART;TZID=Asia/Kolkata:20220520T160000
DTEND;TZID=Asia/Kolkata:20220520T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1207
DTSTAMP:20230914T125954Z
SUMMARY:Fast multivariate multipoint evaluation over finite fields
DESCRIPTION:Speaker: Mrinal Kumar (Indian Institute of Technology Bombay)\n
 \nAbstract: \nMultipoint evaluation is the computational task of evaluatin
 g a polynomial given as a list of coefficients at a given set of inputs. A
  straightforward algorithm for this problem is to just iteratively evaluat
 e the polynomial at each of the inputs. The question of obtaining faster-t
 han-naive (and ideally\, close to linear time) algorithms for this problem
  is a natural and fundamental question in computational algebra. In additi
 on to its own inherent interest\, faster algorithms for multipoint evaluat
 ion are closely related to fast algorithms for other natural algebraic que
 stions like polynomial factorization and modular composition.\nNearly line
 ar time algorithms have been known for the univariate multipoint evaluatio
 n for close to five decades due to a work of Borodin and Moenck but fast a
 lgorithms for the multivariate (or\, even bivariate) version have been muc
 h harder to come by. In a significant improvement to the state of art for 
 this problem in 2008\,  Umans and Kedlaya-Umans gave nearly linear time a
 lgorithms for this problem over field of small characteristic and over all
  finite fields respectively\, provided that the number of variables is at 
 most d^{o(1)} where d is the degree of the input polynomial in every varia
 ble.\nIn this talk\, we will discuss two new algorithms for this problem: 
 the first is a simple and natural algebraic algorithm over not-too-large f
 ields of small characteristic and the second is a (non-algebraic) algorith
 m for this problem over all finite fields. Both these algorithms run in ne
 arly linear time even when the number of variables is large. We will also 
 discuss an application to an upper bound for data structures for polynomia
 l evaluation and to an upper bound on the rigidity of Vandermonde matrices
 .\nThe talk is based on joint works with Vishwas Bhargava\, Sumanta Ghosh\
 , Zeyu Guo\, Chandra Kanta Mohapatra and Chris Umans.\n
URL:https://www.tcs.tifr.res.in/web/events/1207
DTSTART;TZID=Asia/Kolkata:20220530T110000
DTEND;TZID=Asia/Kolkata:20220530T120000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1208
DTSTAMP:20230914T125954Z
SUMMARY:Data-derived weak universal consistency for lossless compression
DESCRIPTION:Speaker: Venkat Anantharam (University of California\, Berkeley
 )\n\nAbstract: \nRich model classes for data may be too complex to admit u
 niformly consistent estimators. In such cases\, it is conventional to sett
 le for pointwise consistent estimators. But this viewpoint has the practic
 al drawback that estimator performance is a function of the unknown model 
 within the model class that is being estimated. Even if an estimator is co
 nsistent\, how well it is doing at any given time may not be clear\, no ma
 tter what the sample size of the observations.\nWe explore how to resolve 
 this issue by studying model classes that may only admit pointwise consist
 ency guarantees\, yet enough information about the unknown model driving t
 he observations needed to gauge estimator accuracy can be inferred from th
 e sample at hand. We would then say that such model classes admit data-der
 ived weak universally consistent estimators.\nIn this work we flesh out th
 is philosophy in the framework of lossless data compression problems over 
 a countable alphabet. Our main contribution is to characterize the model c
 lasses that admit data-derived weak universally consistent lossless compre
 ssion in terms of the presence or not of what we term deceptive distributi
 ons (whether a distribution is deceptive or not is defined in the context 
 of the model class). We also show that the ability to estimate the redunda
 ncy of compressing memoryless sources is equivalent to learning the underl
 ying single-letter marginal in a data-derived fashion.\nThis is joint work
  with Narayana Prasad Santhanam and Wojtek Szpankowski.\nBio: Venkat Anant
 haram is on the faculty of the EECS department at U. C. Berkeley. He recei
 ved his B. Tech. (1980) in Electrical Engineering (Electronics) from IIT M
 adras\, and the M.S. (1982) and Phd. (1986) in Electrical Engineering and 
 M.A. (1984) and C. Phil. (1985) in Mathematics from U. C. Berkeley. From 1
 986 to 1994 he was on the faculty of the School of EE at Cornell Universit
 y. He has been with the EECS department at U. C. Berkeley since 1994. He i
 s a Fellow of the IEEE and a Distinguished Alumnus of IIT Madras.\n
URL:https://www.tcs.tifr.res.in/web/events/1208
DTSTART;TZID=Asia/Kolkata:20220602T160000
DTEND;TZID=Asia/Kolkata:20220602T170000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1209
DTSTAMP:20230914T125954Z
SUMMARY:Techno-Economic Optimization Problems Related to 5G Technology
DESCRIPTION:Speaker: Gourav Saha (Purdue University)\n\nAbstract: \nSpectru
 m sharing and Millimeter Wave Communication are two promising technologies
  for 5G and beyond communication. In a spectrum sharing market\, the regul
 ator (the government) and the wireless service providers are two important
  stakeholders. In this talk\, I will focus mainly on spectrum sharing from
  the perspective of the regulator.\nOne of the objectives of the regulator
  is to maximize the utilization of the spectrum band. I will discuss a Sta
 ckelberg game framework to optimize various parameters of the spectrum mar
 ket in order to maximize spectrum utilization. These parameters include (i
 ) the duration of a spectrum license\, (ii) the number of spectrum bands\,
  and (iii) the ratio of the licensed and unlicensed spectrum bands. Out of
  these three parameters\, optimizing the duration of spectrum license is m
 y most novel contribution and hence I will discuss this topic. Optimizing 
 the duration of spectrum license involves solving a Stackelberg game. I wi
 ll discuss an O(log(T)) algorithm to solve the Stackelberg game\, T being 
 the maximum lease duration\, while the brute-force approach has a time com
 plexity of O(T). I will also briefly discuss a combinatorial optimization 
 viewpoint of solving the Stackelberg Game.\nI will also briefly talk about
  a variant of the Ski-Rental problem that we solved while addressing a cha
 llenge faced by wireless service provider while operating in a spectrum sh
 aring market. I will also briefly discuss my work on designing scheduling 
 algorithms for millimeter-wave communication by using tools from partially
  observable Markov decision processes. Finally\, I will end the seminar wi
 th future research plans related to (i) a variant of multi-armed bandits f
 or directional millimeter-wave communication\, and (ii) spectrum enforceme
 nt for spectrum sharing.\n\nBio: Gourav Saha received a B.E. degree from A
 nna University\, Chennai\, India\, in 2012\, M.S. from Indian Institute of
  Technology Madras\, India\, in 2015\, and Ph.D. from Rensselaer Polytechn
 ic Institute\, Troy\, New York\, in 2020\, all in electrical engineering a
 nd allied areas. He is currently a postdoctoral scholar in the Department 
 of Electrical and Computer Engineering of Purdue University and was previo
 usly a postdoctoral scholar at Ohio State University. His research experie
 nce includes control systems\, online algorithms\, game theory\, the econo
 mics of wireless spectrum sharing market\, and Markov decision process. Hi
 s current research involves designing scheduling and learning algorithms f
 or millimeter-wave communication.\n
URL:https://www.tcs.tifr.res.in/web/events/1209
DTSTART;TZID=Asia/Kolkata:20220616T160000
DTEND;TZID=Asia/Kolkata:20220616T170000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1210
DTSTAMP:20230914T125954Z
SUMMARY:Secure Non-Interactive Reduction and Spectral Analysis of Correlati
 ons
DESCRIPTION:Speaker: Varun Narayanan (Technion\, Israel.)\n\nAbstract: \nCo
 rrelated pairs of random variables are a central concept in information-th
 eoretically secure cryptography. Secure reductions between different corre
 lations have been studied\, and completeness results are known. Further\, 
 the complexity of such reductions is intimately connected with circuit com
 plexity and efficiency of locally decodable codes. As such\, making progre
 ss on these complexity questions faces strong barriers. Motivated by this\
 , in this work\, we study a restricted form of secure reductions --- namel
 y\, Secure Non-Interactive Reductions (SNIR) --- which is still closely re
 lated to the original problem\, and establish several fundamental results 
 and relevant techniques for it.\n\nWe uncover striking connections between
  SNIR and linear algebraic properties of correlations. Specifically\, we d
 efine the spectrum of a correlation\, and show that a target correlation h
 as a SNIR to a source correlation only if the spectrum of the latter conta
 ins the entire spectrum of the former. We also establish a `mirroring lemm
 a' that shows an unexpected symmetry between the two parties in a SNIR\, w
 hen viewed through the lens of spectral analysis. We also use cryptographi
 c insights and elementary linear algebraic analysis to fully characterize 
 the role of common randomness as well as local randomness in SNIRs. We emp
 loy these results to resolve several fundamental questions about SNIRs\, a
 nd to define future directions.\n
URL:https://www.tcs.tifr.res.in/web/events/1210
DTSTART;TZID=Asia/Kolkata:20220624T113000
DTEND;TZID=Asia/Kolkata:20220624T123000
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1211
DTSTAMP:20230914T125954Z
SUMMARY:Overcoming the sample complexity barrier in risk analytics with str
 uctured tail models
DESCRIPTION:Speaker: Karthyek Murthy (Singapore University of Technology & 
 Design (SUTD))\n\nAbstract: \nThe ability to learn and control tail risks\
 , besides being an integral part of quantitative risk management\, is impo
 rtant in running operations requiring high service levels and cyberphysica
 l systems requiring high reliability guarantees. Despite this significance
 \, scalable algorithmic approaches have remained elusive due to the rarity
  with which relevant risky samples are observed. In this talk we examine t
 his bottleneck in two avenues: (i) statistical learning for minimization o
 f tail risks and (ii) simulation of tail risks. We show efficient learning
  and simulation is possible by exploiting the similarity with which risk e
 vents unfold at different scales. This self-similarity\, being a nonparame
 tric characteristic\, leads to satisfyingly expressive model classes and s
 calable algorithms which require exponentially fewer samples than their be
 nchmark counterparts. Efficient learning is made possible by a novel targe
 ted approach towards robustness which could be of interest in broader cont
 exts due to its automatic bias correction property. Specifically\, the sel
 f-similar structure provides a fertile ground to exhibit how mildly restri
 ctive structures can be utilized to debias the error introduced by first-s
 tep model estimation.\n
URL:https://www.tcs.tifr.res.in/web/events/1211
DTSTART;TZID=Asia/Kolkata:20220628T160000
DTEND;TZID=Asia/Kolkata:20220628T170000
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1212
DTSTAMP:20230914T125954Z
SUMMARY:STCS Vigyan Vidushi 2022
DESCRIPTION:Speaker: \n\nAbstract: \nSTCS Vigyan Vidushi 2022\, a summer sc
 hool for women undergraduate and masters students will be held in TIFR Mum
 bai campus from July 2 to July 15\, 2022.\nApplication deadline: April 25\
 , 2022\n \n
URL:https://www.tcs.tifr.res.in/web/events/1212
DTSTART;VALUE=DATE:20220702
DTEND;VALUE=DATE:20220716
LOCATION:AG66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1213
DTSTAMP:20230914T125955Z
SUMMARY:Games of Pursuit and Evasion
DESCRIPTION:Speaker: Neeldhara Misra (IIT Gandhinagar)\n\nAbstract: \nPursu
 it-Evasion games typically involve two types of players: those in pursuit 
 (aka cops) and the so-called evaders (aka robbers). The backdrop is usuall
 y a network with specific rules that dictate how the players can move. The
 se are turn-based games\, and one is usually interested in knowing whether
  and how the evaders can be cornered. We often want to do this as inexpens
 ively and quickly as we can\, which leads to questions about optimizing th
 e number of cops we deploy and the number of rounds that the game will las
 t. It turns out that answers to these questions often have deep connection
 s with the structure of the underlying network. This talk will involve a f
 ew glimpses of such connections. We will also discuss how these games can 
 model real-world situations.\n\nBio: Neeldhara Misra (BSc\, Mount Carmel C
 ollege\, Bangalore\; PhD\, IMSc) is a Smt. Amba and Sri. V S Sastry Chair 
 Associate Professor at IIT Gandhinagar in the discipline of Computer Scien
 ce and Engineering. Prior to this\, she was an INSPIRE faculty fellow at t
 he department of Computer Science and Automation at the Indian Institute o
 f Science\, and graduated from the Institute of Mathematical Sciences\, Ch
 ennai. Her current research interests involve tackling computationally har
 d problems with parameterized algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1213
DTSTART;TZID=Asia/Kolkata:20220705T170000
DTEND;TZID=Asia/Kolkata:20220705T183000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1214
DTSTAMP:20230914T125955Z
SUMMARY:"Every Contact Leaves a Trace": Side Channel and  Micro-architectur
 al Attacks on Modern Cryptosystems
DESCRIPTION:Speaker: Prof. Debdeep Mukhopadhyay (Indian Institute of Techno
 logy\nKharagpur)\n\nAbstract: \nPCryptography plays a vital role in securi
 ng e-business and e-commerce transactions. However\, in spite of their mat
 hematical robustness when these algorithms are implemented they may leak s
 ensitive information via unintended side-channels. The focus of this talk 
 is to provide an overview of these side-channels which exist when the ciph
 ers are executed on various platforms: from embedded systems to more gener
 al-purpose computing systems. More precisely\, we start with introducing p
 opular side-channels wherein the power consumption of a crypto-device can 
 leak the secret key. Subsequently\, we illustrate how faults can be exploi
 ted. In the later part of the talk\, we illustrate how side-channels can a
 lso be extended to more general-purpose computing systems. It is rather ir
 onic that advancements in micro-architectures often are responsible for th
 ese weaknesses. The talk attempts to elucidate the need of analyzing such 
 leakages to develop a holistic understanding of secured systems and transl
 ate the theory to practice.\nAbout the Speaker: Prof. Debdeep Mukhopadhyay
  is currently a Professor at the Department of CSE\, IIT Kharagpur. At IIT
  Kharagpur he initiated Secured Embedded Architecture Laboratory (SEAL)\, 
 focusing on Hardware-Security. He had worked as\, visiting scientist at NT
 U-Singapore\, visiting Associate Professor of NYU-Shanghai\, Assistant Pro
 fessor at IIT Madras\, and Visiting Researcher at NYU-Tandon School of Eng
 ineering\, USA. He holds a Ph.D\, M.S.\, and a B.Tech from IIT Kharagpur. 
 His research interests are on the topics of Cryptographic Engineering and 
 Hardware Security. Recently he is intrigued by adversarial attacks on mach
 ine learning and encrypted computations.\nProf. Mukhopadhyay is the recipi
 ent of the prestigious Shanti Swarup Bhatnagar Award 2021 for Science and 
 Technology and is a Fellow of the Indian National Academy of Engineers. He
  was awarded Khosla National Award from IIT Roorkee 2021\, DST Swarnajayan
 ti Fellowship 2015-16\, INSA Young Scientist award\, INAE Young Engineer A
 ward\, and Associateship for the Indian Academy of Sciences.\n\nZoom link:
  https://zoom.us/j/91427966752 (Passcode: 388629)\nYouTube live link: http
 s://youtu.be/plvzy3fpY_E\n
URL:https://www.tcs.tifr.res.in/web/events/1214
DTSTART;TZID=Asia/Kolkata:20220708T160000
DTEND;TZID=Asia/Kolkata:20220708T170000
LOCATION:ONLINE ASET Colloquium
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1215
DTSTAMP:20230914T125955Z
SUMMARY:The Various Flavours of Computer Systems & Networking Research: A P
 ersonal Journey
DESCRIPTION:Speaker: Ranjita Bhagwan (Microsoft Research Lab - India)\n\nAb
 stract: \nSystems research encompasses a vast variety of domains\, problem
 s\, and solution approaches. While in some cases the research problem is w
 ell-defined\, in other cases defining the problem itself can be a major ta
 sk. Sometimes we arrive at a solution through a novel and elegant idea tha
 t strikes us suddenly\, while at other times we solve the problem by putti
 ng together known ideas in interesting\, counter-intuitive ways. While som
 e solutions are designed\, implemented\, and evaluated in a matter of week
 s\, in other cases the whole process from conceptualization to realization
  can take multiple years from start to finish. In this talk\, through prob
 lems I have worked on over the years\, I will describe these various style
 s of systems research and how each can be enjoyable and rewarding in its o
 wn way.\n\nBio: Ranjita Bhagwan (BTech\, IIT Kharagpur\; MS and PhD\, Univ
  California\, San Diego) is a Senior Principal Researcher at Microsoft Res
 earch India. She has worked for more than a decade on applying machine lea
 rning to improve system reliability\, security and performance. Recently\,
  her work has focused on using data-driven approaches to improve cloud ser
 vices and has led to severalpublications (including a best paper award at 
 USENIX OSDI 2018)\, as well as several tools that are widely used by Micro
 soft's services. She is an ACM Distinguished Member and is the recipient o
 f the 2020 ACM India Outstanding Contributions to Computing by a Woman Awa
 rd.\n
URL:https://www.tcs.tifr.res.in/web/events/1215
DTSTART;TZID=Asia/Kolkata:20220711T170000
DTEND;TZID=Asia/Kolkata:20220711T183000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1216
DTSTAMP:20230914T125955Z
SUMMARY:One-way communication and non-adaptive decision trees
DESCRIPTION:Speaker: Swagato Sanyal (IIT Kharagpur)\n\nAbstract: \nFor two 
 Boolean functions f and g acting on n and m bits respectively\, their comp
 osition f o g is a Boolean function on nm bits defined as follows. Its inp
 ut is thought of as consisting of n blocks\, each m bits long. f o g is co
 mputed first by computing g on each block\, and then by computing f on the
  n resulting bits.\nThis talk is about one-way communication complexity of
  composed functions. Here\, there are two communicating parties\, and the 
 input bits are distributed between them. One party sends a message to the 
 other\, based on which the other party outputs their guess of the value of
  the function on the jointly held input.\nSuppose there is an algorithm fo
 r f that queries few bits of f\, possibly randomly\, and outputs the value
  of f. Suppose further that g is a function on very few bits. Then\, the t
 wo communicating parties can simulate this algorithm and compute the compo
 sed function by communicating about as many bits as the algorithm queries.
 \nThe question we ask is if there is a communication protocol that is sign
 ificantly cheaper than this naive protocol. We address this question for t
 wo choices of g: the AND function and the Inner-Product function.\nThis ta
 lk is based on joint work with Nikhil Mande and Suhail Sherif.\n\nLink to 
 the pre-print: https://arxiv.org/pdf/2105.01963.pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1216
DTSTART;TZID=Asia/Kolkata:20220712T153000
DTEND;TZID=Asia/Kolkata:20220712T163000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1217
DTSTAMP:20230914T125955Z
SUMMARY:The complexity of formal proofs
DESCRIPTION:Speaker: Meena Mahajan (Institute of Mathematical Sciences\, Ch
 ennai.)\n\nAbstract: \nA proof of a statement convinces the person/entity 
 addressed that the statement is true. Intuitively\, a good proof is short\
 , and easy to verify. A formal proof must convince an automated checking p
 rogram (that may have limited resources). This talk discusses why we care 
 about formal proofs\, how we can design good formal proofs\, and situation
 s where we hit a wall. Bio: Meena Mahajan (BTech and MTech\, IIT Bombay\; 
 PhD\, IIT Madras) s a professor in the theoretical computer science group 
 at The Institute of Mathematical Sciences\, HBNI\, Chennai. Her research i
 nterests encompass many aspects of computational complexity theory\, inclu
 ding Boolean function complexity\, algebraic circuits\, proof complexity\,
  and space-bounded computation. She is a fellow of the Indian Academy of S
 ciences.\n
URL:https://www.tcs.tifr.res.in/web/events/1217
DTSTART;TZID=Asia/Kolkata:20220713T170000
DTEND;TZID=Asia/Kolkata:20220713T183000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1218
DTSTAMP:20230914T125955Z
SUMMARY:On Complexity measures of Boolean functions
DESCRIPTION:Speaker: Tulasi mohan Molli\n\nAbstract: \nBoolean functions ca
 pture various problems and situations arising in computer science and othe
 r areas. In this synopsis\, we study boolean functions using two complexit
 y measures.\nIn the first part of the talk\, we will focus on the Probabil
 istic degree of OR over Reals. This is based on joint work with Bhandari\,
  Harsha and Srinivasan. In this part\, we will look at the construction of
  a Probabilistic Polynomial for OR over Reals\, which improves on the prev
 ious best construction due to Toda-Ogiwara and Beigel\, Tarui\, Reingold a
 nd Speilman.  We will also look at a lower bound on the Probabilistic deg
 ree of OR which matches our upper bound construction in a restricted setti
 ng.\n\nIn the second part\, we will look at a bunch of complexity measures
  which arise out of the Fourier representation of Boolean functions and st
 udy the relationship between them.  This is based on joint work with Chak
 raborty\, Mande\, Mittal\, Paraashar and Sanyal. In this part\, we will fo
 cus on a couple of upper bounds on Fourier rank in terms of Fourier sparsi
 ty\, weight\, Fourier max-entropy and  Fourier max-rank entropy. We will 
 also exhibit functions which match these bounds.\n\nMeeting URL : https://
 zoom.us/j/98513182619?pwd=WjZDWFhVVVdYM0NhZGZjdGtObjhvQT09\nMeeting ID : 9
 8513182619\nPasscode : 59290580\n
URL:https://www.tcs.tifr.res.in/web/events/1218
DTSTART;TZID=Asia/Kolkata:20220715T140000
DTEND;TZID=Asia/Kolkata:20220715T150000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1219
DTSTAMP:20230914T125955Z
SUMMARY:Oral qualifier
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nA talk on
  Pseudo-determinism.\n
URL:https://www.tcs.tifr.res.in/web/events/1219
DTSTART;TZID=Asia/Kolkata:20220718T103000
DTEND;TZID=Asia/Kolkata:20220718T113000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1220
DTSTAMP:20230914T125955Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Yeshwant Chandrakant  Pandit\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1220
DTSTART;TZID=Asia/Kolkata:20220719T150000
DTEND;TZID=Asia/Kolkata:20220719T163000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1221
DTSTAMP:20230914T125955Z
SUMMARY:Best arm Identification in Multi-Armed Bandits
DESCRIPTION:Speaker: Agniv Bandyopadhyay\n\nAbstract: \nPapers by: \n(1)"Be
 st Arm Identification in Multi-Armed Bandits" by Audibert and Bubeck\, 201
 0.\n(2)"Tight (Lower) Bounds for the Fixed Budget Best Arm IdentificationB
 andit Problem" Carpentier and Locatelli 2016.\n\nPaper (1) gives two algor
 ithms for the best arm identification problem in stochastic multi-armed ba
 ndits under a fixed budget: Upper Confidence Bound-Exploration(UCB-E) and 
 Successive Reject(SR). They also prove a lower bound of error probability 
 in the limited budget setting. Paper (2) later improved that lower bound a
 nd proved that it matches the upper bound of the probability of error for 
 the SR-Algorithm\, thus proving its optimality. We'll look at the results 
 established in Paper (1) and look through paper (2) if time permits.\n\nJo
 ining Link: https://us02web.zoom.us/j/9290331190\n
URL:https://www.tcs.tifr.res.in/web/events/1221
DTSTART;TZID=Asia/Kolkata:20220720T150000
DTEND;TZID=Asia/Kolkata:20220720T160000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1222
DTSTAMP:20230914T125955Z
SUMMARY:Written Qualifier
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1222
DTSTART;TZID=Asia/Kolkata:20220721T093000
DTEND;TZID=Asia/Kolkata:20220721T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1223
DTSTAMP:20230914T125955Z
SUMMARY:Written Qualifier
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1223
DTSTART;TZID=Asia/Kolkata:20220722T093000
DTEND;TZID=Asia/Kolkata:20220722T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1224
DTSTAMP:20230914T125955Z
SUMMARY:An almost-efficient deterministic parallel algorithm for Bipartite 
 Perfect Matching
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nWe will try to underst
 and the paper "Bipartite Perfect Matching is in quasi-NC" by Fenner\, Gurj
 ar and Thierauf (2016). They achieved an almost complete derandomization o
 f the Isolation Lemma (Mulmuley\, Vazirani\, Vazirani) for perfect matchin
 gs in bipartite graphs and thus the result stated in the title. There are 
 no prerequisites for the talk\; familiarity with linear programming would 
 be helpful.\n
URL:https://www.tcs.tifr.res.in/web/events/1224
DTSTART;TZID=Asia/Kolkata:20220722T160000
DTEND;TZID=Asia/Kolkata:20220722T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1225
DTSTAMP:20230914T125955Z
SUMMARY:Learning Optimal Bids in Second Price Auctions with Temporal and Ov
 erlapping Targeting Constraints
DESCRIPTION:Speaker: Ravi R. Mazumdar (University of Waterloo)\n\nAbstract:
  \nAd placement in web-browsing and wireless mobiles is an increasingly im
 portant component of the advertisement market. The market size is over $ 1
 00 billion and counting. The mechanism is as follows: when a user opens a 
 webpage or mobile ap a message is sent to an exchange where multiple bidde
 rs have the possibility of placing an ad that would target the right user\
 , eg. age\, sex\, location\, etc. The ad that is displayed corresponds to 
 the bidder who bids the highest while the cost is calculated according to 
 a first or second price. Typically bidders are DSP (Demand Side Platforms)
  that aggregate bids on behalf of clients who wish to run a campaign for a
  given length of time with certain targeting criteria. The goal is to mini
 mize the total cost of obtaining the required number of impressions (ads t
 hat meet targeting criteria) over the duration of a contract. The real tim
 e constraint is that bidding must be done within 100ms.\n\nIn this talk I 
 will build upon the theory that we had earlier developed for computing the
  least cost bids in the second price context. This involves the notion of 
 an information state for the problem. There is a very rich primal-dual the
 ory that emerges\, one in the so called impressions space and the other in
  the contracts space. Computationally and structurally the primal and dual
  views of the optimization have different properties that can be exploited
  to come up with fast algorithms.\n\nThe optimal solutions depend on solvi
 ng a constrained convex optimization problem when the information state is
  known. However this is not readily available and thus there is the proble
 m of learning the information state. We show that in the second price case
 \, stochastic approximation (SA) algorithms that operate on censored data 
 (prices are only known by a bidder when the bidder wins) can be devised th
 at solve the constrained optimization problem without learning the informa
 tion state explicitly and we prove their convergence. Finally I will prese
 nt the dynamic behaviour through simulations.\nJoint work with Ryan Kinnea
 r (Waterloo) and Peter Marbach (Toronto). We thank Addictive Mobility Inc.
 \, a Pelmorex company for having proposed the problem and to Addictive Mob
 ility\, Ontario OCE VIP II\, and NSERC funding the work.\n\nBio: The speak
 er was educated at the Indian Institute of Technology\, Bombay (B.Tech\, 1
 977)\, Imperial College\, London (MSc\, DIC\, 1978) and obtained his PhD i
 n Control Theory under A. V. Balakrishnan at UCLA in 1983. He is currently
  a University Research Chair Professor in the Dept. of ECE at the Universi
 ty of Waterloo\, Ont.\, Canada where he has been since September 2004. Pri
 or to this he was Professor of ECE at Purdue University\, West Lafayette\,
  USA. Since 2012 he is a D.J. Gandhi Distinguished Visiting Professor at t
 he Indian Institute of Technology\, Bombay\, India and since May 2019 an A
 djunct Professor at the Tata Institute of Fundamental Research (TIFR)\, Mu
 mbai. He is a Fellow of the IEEE and the Royal Statistical Society. He is 
 a recipient of the INFOCOM 2006 Best Paper Award\, the ITC-27 2015 Best Pa
 per Award\, the Performance 2015 Best Paper Award and was runner-up for th
 e Best Paper Award at INFOCOM 1998. His research interests are in stochast
 ic modelling and analysis applied to complex networks and statistical infe
 rence.\nYouTube Link: https://youtu.be/dA44DA8gQDM\n
URL:https://www.tcs.tifr.res.in/web/events/1225
DTSTART;TZID=Asia/Kolkata:20220725T160000
DTEND;TZID=Asia/Kolkata:20220725T170000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1226
DTSTAMP:20230914T125955Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Santanu Das\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1226
DTSTART;TZID=Asia/Kolkata:20220726T150000
DTEND;TZID=Asia/Kolkata:20220726T160000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1227
DTSTAMP:20230914T125955Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Sunandan  Sharma\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1227
DTSTART;TZID=Asia/Kolkata:20220728T150000
DTEND;TZID=Asia/Kolkata:20220728T160000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1228
DTSTAMP:20230914T125955Z
SUMMARY:Multi-Armed Bandits and Heavy-Tailed Distributions
DESCRIPTION:Speaker: Shubhada Agrawal\n\nAbstract: \nMulti-armed bandit (MA
 B) is a popular framework for decision-making in an uncertain environment.
  In its classical setup\, the algorithm has access to a fixed and finite s
 et of unknown\, independent probability distributions or arms. At each tim
 e step\, having observed the outcomes of all the previous actions\, the al
 gorithm chooses one of the K arms and observes an independent sample drawn
  from the underlying distribution\, which may be viewed as a reward. The a
 lgorithm's goal is either to maximize the accumulated rewards or to identi
 fy the "best" arm in as few samples as possible\, for an appropriate defin
 ition of "best".\nVariants of these classical formulations have been widel
 y studied. Tight lower bounds on associated performance metrics and algori
 thms matching these lower bounds exactly have been developed assuming that
  the arm-distributions are either Sub-Gaussian or come from a single param
 eter exponential family (SPEF)\, for example\, Gaussian with known varianc
 e or Bernoulli. However\, in practice\, the distributions may not belong t
 o these simple classes. Developing lower bounds and optimal algorithms for
  the general class of distributions largely remained open mainly because o
 f the need for new sets of tools and techniques for the analysis in genera
 lity.\nIn this dissertation\, we undertake a detailed study of the MAB pro
 blems allowing for all the distributions with a known uniform bound on the
 ir  $(1+\\epsilon)^{th}$ moments\, for some $\\epsilon > 0$. This class s
 ubsumes a large class of heavy-tailed distributions. We develop a framewor
 k with essential tools and concentration inequalities and use it for desig
 ning optimal algorithms for 3 different variants of the MAB problem. In th
 is talk\, we will look at these optimal algorithms for the classical frame
 works - regret minimization and best-arm identification.\nWe will also inv
 estigate the new concentration inequalities that we develop for proving th
 eoretical guarantees of the algorithms. These can be used to construct tig
 ht\, anytime-valid confidence intervals (CIs) for various statistics\, for
  example\, mean\, quantile\, CVaR\, etc.\, and may be of independent inter
 est.\nThe above results were obtained in collaborations involving Sandeep 
 Juneja\, Wouter M. Koolen and Peter Glynn.\n\nZoom link: https://us02web.z
 oom.us/j/9290331190\n
URL:https://www.tcs.tifr.res.in/web/events/1228
DTSTART;TZID=Asia/Kolkata:20220728T153000
DTEND;TZID=Asia/Kolkata:20220728T163000
LOCATION:Via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1229
DTSTAMP:20230914T125955Z
SUMMARY:Byzantine Multiple Access Channels
DESCRIPTION:Speaker: Neha Sangwan\n\nAbstract: \nWireless Internet of thing
 s (IoTs) consists of devices with varying levels of security connected ove
 r a shared communication medium. This can allow compromised devices to dev
 iate from the communication protocol and potentially disrupt the communica
 tion of other devices. The existing theoretical models of communication\, 
 for the most part\, assume users/devices which do not deviate maliciously 
 from the prescribed protocols. While attacks by external adversaries such 
 as jammers and eavesdroppers have been studied\, insider/ Byzantine attack
 s have not received much attention. This is precisely the form that attack
 s on IoTs take.  As a first step towards this\, we consider the uplink of 
 a network and model it using a  multiple access channel where users may de
 viate maliciously. In this talk\, we will investigate this model under dif
 ferent security guarantees: 1) When can honest devices communicate reliabl
 y even in the presence of malicious devices? 2) Is it possible to identify
  the malicious devices (when present) so that they can be taken offline? 3
 ) When is it possible to detect the presence of malicious devices (without
  necessarily identifying them)?\n\nThe talk is based on joint work with Ma
 yank Bakshi\, Bikash Kumar Dey and Vinod Prabhakaran.\n
URL:https://www.tcs.tifr.res.in/web/events/1229
DTSTART;TZID=Asia/Kolkata:20220729T140000
DTEND;TZID=Asia/Kolkata:20220729T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1230
DTSTAMP:20230914T125955Z
SUMMARY:Binary Hypothesis Testing with Deterministic Finite-Memory Decision
  Rules
DESCRIPTION:Speaker: Hari Krishnan P A\n\nAbstract: \nIn this talk\, we wil
 l consider the problem of binary hypothesis testing with finite memory. Co
 nsider a sequence of IID random variables with expectation p under hypothe
 sis H_0 and q under hypothesis H_1. Consider a finite-state machine with s
 tate M_n at time n. Let the state of the system be governed by the rule M_
 n = f(M_{n-1}\,X_n) where f is a deterministic time-invariant function. As
 sume that we let this process run for a very long time and then make a dec
 ision according to some mapping from the state space to the hypothesis spa
 ce. We will bound the error probability of any hypothesis testing system.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1230
DTSTART;TZID=Asia/Kolkata:20220805T160000
DTEND;TZID=Asia/Kolkata:20220805T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1231
DTSTAMP:20230914T125955Z
SUMMARY:Gossiping in random graphs
DESCRIPTION:Speaker: Ayalvadi Ganesh (University of Bristol)\n\nAbstract: \
 nConsider a set of n agents\, each of whom has a single message to convey 
 to all other agents. The messages are all of the same length. Time is divi
 ded into rounds\, and during each round\, each agent may broadcast a singl
 e message. Agents are represented as nodes of a directed communication gra
 ph\, and a broadcast is received error-free by all (out)-neighbours of the
  broadcasting node. The problem is to minimise the number of rounds until 
 all agents have received all messages.\n\nThis is known as the gossiping p
 roblem\, and various versions of it have been studied. In our version\, th
 e communication graph is a dense directed Erdos-Renyi random graph G(n\,p)
 \, and we seek simple decentralised gossip algorithms. We consider two alg
 orithms\, random relaying and random linear network coding. We consider a 
 sequence of graphs with p fixed and n tending to infinity. Our main result
 s are that random relaying requires Theta(log n) rounds\, whereas random l
 inear network coding requires only a constant number of rounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1231
DTSTART;TZID=Asia/Kolkata:20220812T110000
DTEND;TZID=Asia/Kolkata:20220812T120000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1232
DTSTAMP:20230914T125955Z
SUMMARY:A game theoretic proof of RANKING algorithm
DESCRIPTION:Speaker: Soumyajit Pyne\n\nAbstract: \nOnline Bipartitie Matchi
 ng was first introduced by Karp\, Vazirani and Vazirani (STOC’90). In th
 eir seminal paper they had inroduced the RANKING algorithm which admits a 
 tight competitive ratio of 1-1/e. Since then multiple proofs of RANKING ha
 ve been published. In this talk\, we shall look at a simple Game Theoretic
  approach to proving the competitive ratio of RANKING\, avoiding linear pr
 ogramming arguments. The proof is based on the paper by Eden\, Feldman\, F
 iat and Segal (https://arxiv.org/abs/1804.06637).\n
URL:https://www.tcs.tifr.res.in/web/events/1232
DTSTART;TZID=Asia/Kolkata:20220812T160000
DTEND;TZID=Asia/Kolkata:20220812T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1233
DTSTAMP:20230914T125955Z
SUMMARY:Exact analysis of Generalization error in Generalized Linear Models
DESCRIPTION:Speaker: Parthe Pandit (UC San Diego)\n\nAbstract: \nGLMs are a
  powerful class of models applied ubiquitously in machine learning and sig
 nal processing applications. Learning these models often involves iterativ
 ely solving non-convex optimization problems. I will present an exact stat
 istical analysis of learning in these models in a high dimensional setting
 . This framework is built on new developments in Random Matrix Theory\, an
 d does not rely on convexity. Using this framework\, we can now analyze th
 e effect of several design choices on the generalization error of the lear
 ned model. Example design choices include loss function\, regularization\,
  feature covariance\, train-test mismatch.\nBio: Parthe Pandit is a Simons
  postdoctoral fellow at the Halıcıoğlu Data Science Institute at UC San
  Diego. He obtained a PhD in ECE and MS in Statistics both from UCLA\, and
  a dual degree in EE from IIT Bombay. He is a recipient of the Jack K Wolf
  student paper award at ISIT 2019. He has also been a research intern at A
 mazon and Citadel LLC.\n(Halıcıoğlu is pronounced as Haali-Jio-Lu)\n
URL:https://www.tcs.tifr.res.in/web/events/1233
DTSTART;TZID=Asia/Kolkata:20220816T160000
DTEND;TZID=Asia/Kolkata:20220816T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1234
DTSTAMP:20230914T125955Z
SUMMARY:KO codes: Inventing Non-linear Encoding and Decoding for Reliable W
 ireless Communication via Deep-learning
DESCRIPTION:Speaker: Ashok Vardhan Makkuva (UIUC and EPFL)\n\nAbstract: \nL
 andmark codes underpin reliable physical layer communication\, e.g.\, Reed
 -Muller\, BCH\, Convolutional\, Turbo\, LDPC and Polar codes: each is a li
 near code and represents a mathematical breakthrough. The impact on humani
 ty is huge: each of these codes has been used in global wireless communica
 tion standards (satellite\, WiFi\, cellular). Traditionally\, the design o
 f codes has been driven by human-ingenuity and hence the progress is spora
 dic. Can we automate and accelerate this process of discovering codes?\nIn
  this talk\, I will talk about KO codes\, a new family of computationally 
 efficient deep-learning driven codes that outperform the state-of-the-art 
 reliability performance on the standardized AWGN channel. KO codes beat st
 ate-of-the-art Reed-Muller and Polar codes\, under the low-complexity succ
 essive cancellation decoding\, in the challenging short-to-medium block le
 ngth regime on the AWGN channel. We show that the gains of KO codes are pr
 imarily due to the nonlinear mapping of information bits directly to trans
 mit real symbols (bypassing modulation) and yet possess an efficient\, hig
 h performance decoder. The key technical innovation that renders this poss
 ible is the design of a novel family of neural architectures inspired by t
 he computation tree of the Kronecker Operation (KO) central to Reed-Muller
  and Polar codes. These architectures pave the way for the discovery of a 
 much richer class of hitherto unexplored nonlinear algebraic structures. A
 nd more interestingly\, despite having a lot of encoding and decoding stru
 cture\, KO codes exhibit striking similarity to random Gaussian codes!\nBi
 o: Ashok is an incoming postdoctoral associate at EPFL with Prof. Michael 
 Gastpar. He recently obtained his PhD in ECE from UIUC\, advised by Prof. 
 Pramod Viswanath. He also obtained his Masters in ECE (advised by Prof. Yi
 hong Wu) from UIUC in 2017 and Bachelors in EE (advised by Prof. Vivek Bor
 kar) with a minor in Mathematics from IIT Bombay in 2015. His current rese
 arch interests are in theoretical and algorithmic aspects of machine learn
 ing and information theory. He is a recipient of Best Paper Award from ACM
  MobiHoc 2019. He is also a recipient of several graduate student awards a
 nd fellowships including Joan and Lalit Bahl Fellowship (twice)\, Sundaram
  Seshu International Student Fellowship\, and is a finalist for the Qualco
 mm Innovation Fellowship 2018. Outside research\, he likes to learn new la
 nguages\, watch and read about international films\, remembering movie tri
 via and cooking. For more details about him\, please visit http://makkuva2
 .web.engr.illinois.edu/\n
URL:https://www.tcs.tifr.res.in/web/events/1234
DTSTART;TZID=Asia/Kolkata:20220823T160000
DTEND;TZID=Asia/Kolkata:20220823T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1235
DTSTAMP:20230914T125955Z
SUMMARY:New Techniques and Results in Mixture Models
DESCRIPTION:Speaker: Soumyabrata Pal (Google Research\, India.)\n\nAbstract
 : \nMixture models\, introduced in 1894 by Karl Pearson is very popular in
  both theory and practice. Mixture models with high dimensional latent par
 ameter vectors are widely used to fit complex multimodal datasets as they 
 allow representation of the presence of sub-populations within the overall
  population. The primary difficulty in learning mixture models is that the
  observed data does not identify the subpopulation to which an individual 
 observation belongs.\nIn this talk\, I will introduce the problem of suppo
 rt recovery of the unknown parameter vectors when they are known to be spa
 rse. I will present a very generic framework (including a novel tensor-bas
 ed algorithm) for support recovery by using estimates of the number of unk
 nown vectors having non-zero entries in small subsets of indices. Then\, t
 his framework is applied by showing a variety of techniques to estimate th
 e aforementioned quantities in different mixture models. Our results for s
 upport recovery are quite general\, namely they are applicable to 1) Mixtu
 res of many different canonical distributions 2) Mixtures of linear regres
 sions and linear classifiers. Finally\, I will demonstrate some experiment
 s on real world datasets that support our theoretical guarantees.\nBased o
 n papers that appeared in NeurIPS 20\, NeurIPS 21 and AISTATS 22.\nBio: So
 umyabrata is a Postdoctoral Researcher at Google Research\, India. Soumyab
 rata completed his Ph.D in the Computer Science Department (CICS) at the U
 niversity of Massachusetts Amherst advised by Dr. Arya Mazumdar. During th
 at time\, he was a Visiting Graduate Student at the University of Californ
 ia San Diego in 2021 and interned at Ernst & Young AI Lab and Amazon AI an
 d Search. His research interests are Theoretical Machine Learning\, Applie
 d Statistics and Information Theory. In particular\, his research is focus
 ed on designing efficient and scalable algorithms for Statistical recovery
 /reconstruction problems under different structural assumptions on the dat
 a generating mechanism such as sparsity\, low-rank\, presence of latent cl
 usters among others.\nWebsite: https://soumyabratap.github.io/\n
URL:https://www.tcs.tifr.res.in/web/events/1235
DTSTART;TZID=Asia/Kolkata:20220830T160000
DTEND;TZID=Asia/Kolkata:20220830T170000
LOCATION:Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1236
DTSTAMP:20230914T125955Z
SUMMARY:A Study of Information Transmission over Quantum Channels in the On
 e-Shot Setting
DESCRIPTION:Speaker: Sayantan  Chakraborty\n\nAbstract: \nIn this thesis we
  tackle two main problems :\n1. Coding techniques for sending quantum info
 rmation across a multi-terminal quantum channel in the one-shot regime.\n2
 . Coding techniques for sending private information across a classical-qua
 ntum multiple access channel\, while ensuring that the transmitted message
 s remain hidden from an eavesdropper.\nWe first consider the Quantum Multi
 ple Access Channel or QMAC and show the existence of coding theorems for t
 he task of sending EPR pairs from two independent senders Alice and Bob to
  a receiver Charlie using this channel. For this purpose we develop two ma
 in tools:\n1. A multi-terminal decoupling theorem.\n2. One-shot quantum ra
 te splitting.\nWhile the multi-terminal decoupling theorem allows us to re
 cover an ideal pentagonal achievable rate region\, for entanglement transm
 ission across the QMAC\, these bounds are not easily generalised to recove
 r the best inner bounds known for this problem in the asymptotic iid setti
 ng\, due to the issue of Simultaneous Smoothing\, which remains a major op
 en problem in quantum information theory.\nTo get around this problem\, we
  adapt the classical iid technique of rate splitting to the one-shot quant
 um setting. This new technique allows us to recover the best known achieva
 ble rate region known for this problem in the asymptotic iid regime. Our t
 echniques also allow us to show the existence of coding schemes which achi
 eve the best known non-trivial rate region for entanglement transmission a
 cross the Quantum Interference Channel or QIC\, both in the one-shot and i
 n the asymptotic iid regime.\nWe next consider the problem of sending priv
 ate classical information from two independent senders Alice and Bob to a 
 legitimate receiver Charlie\, in the presence of an eavesdropper Eve\, via
  a wiretap classical-quantum MAC. This problem is considerably hard to sol
 ve since we require that Alice and Bob's messages should be jointly secret
  from Eve\, which requires a joint quantum covering lemma.\nUnfortunately\
 , such a lemma remains out of reach of current techniques\, since it reduc
 es to the Simultaneous Smoothing conjecture.\nWe get around this issue by 
 developing a successive cancellation style covering lemma which\, along wi
 th some other tools\, allows us to recover a non-trivial achievable rate r
 egion in the one-shot regime and also recover the natural pentagonal rate 
 region that one would expect for this problem\, in the asymptotic iid regi
 me.\n
URL:https://www.tcs.tifr.res.in/web/events/1236
DTSTART;TZID=Asia/Kolkata:20220901T173000
DTEND;TZID=Asia/Kolkata:20220901T193000
LOCATION:Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1237
DTSTAMP:20230914T125956Z
SUMMARY:A brief introduction to polar codes
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nIn his se
 minal work in 1948 (A Mathematical Theory of Communication) Shannon introd
 uced the capacity of a channel: the maximum rate at which information can 
 be reliably communicated across a channel. Shannon proved that for every m
 emoryless channel there exists error correcting codes which achieve rate a
 rbitrarily close to capacity. However Shannon's proof was an existential o
 ne: he was unable to give any efficient encoding and decoding scheme that 
 would allow communication over a channel at rates close to capacity. This 
 remained a major open problem until 2008 when Erikan introduced polar code
 s. These codes achieve Shannon capacity over any symmetric memoryless chan
 nel\, and in special cases such as BSC (binary symmetric channel) and BEC 
 (binary erasure channel) have efficient decoding algorithms as well. We sh
 all discuss polar codes in the special case of BSC: we shall give an overv
 iew of their encoding and decoding schemes.\n
URL:https://www.tcs.tifr.res.in/web/events/1237
DTSTART;TZID=Asia/Kolkata:20220902T140000
DTEND;TZID=Asia/Kolkata:20220902T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1238
DTSTAMP:20230914T125956Z
SUMMARY:M.Sc. thesis waiver presentation
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nOne of th
 e most active research directions in quantum computing currently is establ
 ishing quantum supremacy results: coming up with computational tasks which
  a quantum algorithm can solve super-polynomially faster than a classical 
 algorithm. In this talk we look at the particular computational model of q
 uery complexity: where the algorithm has to evaluate a known function on a
 n unknown input\; it can access the input by asking queries to an oracle a
 nd has to minimize the number of queries. Internal computations are assume
 d to have no cost. We can define the quantum variant of query complexity w
 here the quantum algorithm has access to an oracle representing the input 
 and can ask queries in superposition.\n\nOne of the long-standing question
 s in this direction is the following: given a quantum query algorithm for 
 a Boolean function (defined on a subset of the Boolean hypercube with at l
 east inverse polynomial density) making d queries\, does there exist a cla
 ssical query algorithm which makes at most poly(d) queries and approximate
 s the output probability of the quantum algorithm on most inputs? We shall
  discuss the body of previous work done on this question: weak results tha
 t are known\, a recent attempt to resolve the conjecture which turned out 
 to have a fatal flaw and our attempts to fix the argument.\n
URL:https://www.tcs.tifr.res.in/web/events/1238
DTSTART;TZID=Asia/Kolkata:20220908T103000
DTEND;TZID=Asia/Kolkata:20220908T120000
LOCATION:D-405 (D-Block Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1239
DTSTAMP:20230914T125956Z
SUMMARY:YouTube video by Ryan O'Donnell
DESCRIPTION:Speaker: \n\nAbstract: \nPlease find the details of this week's
  student seminar.\n\nThis week\, we shall be watching a YouTube video by R
 yan O'Donnell. Here\, he will be presenting a complete proof of Hastad's S
 witching Lemma. This video was suggested to me by Ashutosh.\n\nLink : http
 s://www.youtube.com/watch?v=ahW96yYmWx0\n\nRegards\,\nArghya\n
URL:https://www.tcs.tifr.res.in/web/events/1239
DTSTART;TZID=Asia/Kolkata:20220909T160000
DTEND;TZID=Asia/Kolkata:20220909T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1240
DTSTAMP:20230914T125956Z
SUMMARY:The L* Algorihthm for Constructing Deterministic Finite Automatons
DESCRIPTION:Speaker: Malhar Ajit  Managoli\n\nAbstract: \nSuppose we are pr
 esented with a language like L = {x ∈ {0\, 1}| The third to last bit is 
 1}. We can intuitively understand this language. Given a string we can qui
 ckly tell if it is in L or not. Coming up with a DFA for a language from s
 cratch is somewhat more difficult.\n\nThe L* algorithm is one way of writi
 ng a formal method which we use in finding a DFA for a regular language. I
 n this talk we will see a description of the L* Algorithm and a proof of c
 orrectness.\n
URL:https://www.tcs.tifr.res.in/web/events/1240
DTSTART;TZID=Asia/Kolkata:20220916T160000
DTEND;TZID=Asia/Kolkata:20220916T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1241
DTSTAMP:20230914T125956Z
SUMMARY:Binary linear error correcting codes with sufficient symmetry achie
 ve capacity on the erasure channel
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nConstruct
 ing error correcting codes that achieve Shannon capacity on a given memory
 less channel and have efficient encoding and decoding algorithms has been 
 a major line of recent research. In this talk\, we shall discuss the error
  correcting capacity of codes on the binary erasure channel. We will show 
 that sufficient symmetry alone implies a linear error correcting code achi
 eves capacity on BEC. In particular\, we shall prove the following results
 : (i) Consider a family of linear binary error correcting codes (parameter
 ized by block length) approaching constant rate. Suppose the transitive gr
 oup of each code is doubly symmetric and the distance satisfies log(distan
 ce)/log(block length)->1. Then this family achieves capacity on BEC. This 
 implies that BCH codes achieve capacity on BEC. (ii) Binary Reed Muller co
 des achieve capacity on BEC. In this proof\, we shall not use any special 
 properties of Reed Muller codes other than the fact that their symmetry gr
 oup contains GL_n(F_2) and that a family of Reed Muller codes approaching 
 constant rate satisfies log(distance)/log(block length)->1/2.\n
URL:https://www.tcs.tifr.res.in/web/events/1241
DTSTART;TZID=Asia/Kolkata:20220923T160000
DTEND;TZID=Asia/Kolkata:20220923T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1242
DTSTAMP:20230914T125956Z
SUMMARY:Searching valiantly for LTCs
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR\, Mumbai.)\n\nAbstract: \nA des
 irable property for a code is "local testability" - being able to look at 
 a small number of locations and determine if the received word is a codewo
 rd or far from one. Given two base codes\, one can construct a tensor code
 : matrices with rows in one code\, and columns in the other. A natural loc
 al test for this would be to randomly pick a row or column and check if it
  is in that base code. Unfortunately\, this fails - we will look at a neat
  counterexample by Paul Valiant (2005). However\, if one of the codes is "
 smooth"\, the test works. Time permitting\, we will look at the definition
  of smoothness (later relaxed to "weakly smooth") and a sketch of the anal
 ysis in that case.\n
URL:https://www.tcs.tifr.res.in/web/events/1242
DTSTART;TZID=Asia/Kolkata:20220930T160000
DTEND;TZID=Asia/Kolkata:20220930T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1243
DTSTAMP:20230914T125956Z
SUMMARY:Universal Caching
DESCRIPTION:Speaker: Ativ Joshi (CMI)\n\nAbstract: \nIn the learning litera
 ture\, the performance of an online policy is commonly measured in terms o
 f the static regret metric\, which compares the cumulative loss of an onli
 ne policy to that of an optimal benchmark in hindsight. In the definition 
 of static regret\, the benchmark policy remains fixed throughout the time 
 horizon. Naturally\, the resulting regret bounds become loose in non-stati
 onary settings\, where fixed benchmarks often suffer from poor performance
 . In this paper\, we investigate a stronger notion of regret minimization 
 in the context of an online caching problem. In particular\, we allow the 
 action of the offline benchmark at any round to be decided by a finite sta
 te predictor possessing arbitrarily many states. Using ideas from the univ
 ersal prediction literature in information theory\, we propose an efficien
 t online caching policy with an adaptive sublinear regret bound. To the be
 st of our knowledge\, this is the first data-dependent regret bound known 
 for the universal caching problem. We establish this result by combining a
  recently-proposed online caching policy with an incremental parsing algor
 ithm\, e.g. Lempel-Ziv '78. Our methods also yield a simpler learning-theo
 retic proof of the improved regret bound\, as opposed to the more involved
  and problem-specific combinatorial arguments used in the earlier works.\n
URL:https://www.tcs.tifr.res.in/web/events/1243
DTSTART;TZID=Asia/Kolkata:20221007T160000
DTEND;TZID=Asia/Kolkata:20221007T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1244
DTSTAMP:20230914T125956Z
SUMMARY:Streaming Algorithms for Maximum Weighted Matching
DESCRIPTION:Speaker: Pavel Dvorak\n\nAbstract: \nI will talk about the maxi
 mum weighted matching problem in the streaming model. In this model\, an a
 lgorithm receives edges of a graph one by one. When the stream ends\, it s
 hould output an approximation of the maximum weighted matching of the inpu
 t graph using only linear (or subquadratic) memory. First\, I will present
  an algorithm of Paz and Swartzmann\, who gave a 2-approximation for this 
 problem. Further\, I will talk about how to use this algorithm for design 
 algorithms in sliding window model. In this model\, when an edge arrives\,
  the algorithm should output an approximation of the maximum weighted matc
 hing in a graph spanned by last L edges\, where L is a parameter of the mo
 del.\n\nThis is a joint work with Cezar-Mihail Alexandru\, Christian Konra
 d\, and Kheeran K. Naidu.\n
URL:https://www.tcs.tifr.res.in/web/events/1244
DTSTART;TZID=Asia/Kolkata:20221014T160000
DTEND;TZID=Asia/Kolkata:20221014T170000
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1245
DTSTAMP:20230914T125956Z
SUMMARY:Polynomial time partition oracles for bounded degree planar graphs
DESCRIPTION:Speaker: Akash Kumar (EPFL Lausanne\, Switzerland.)\n\nAbstract
 : \nTake a planar graph with maximum degree d. These graphs admit a hyperf
 inite decompositions\, where\, for a sufficiently small \\epsilon > 0\, on
 e removes \\epsilon dn edges to get connected components of size independe
 nt of n. An important tool for sublinear algorithms and property testing f
 or such classes is the partition oracle. A partition oracle is a local pro
 cedure that gives "consistent" access to a hyperfinite decomposition\, wit
 hout any preprocessing. Given a query vertex v\, the partition oracle outp
 uts the component containing v in time independent of n. All the answers a
 re consistent with a single hyperfinite decomposition. In this talk\, I wi
 ll describe a partition oracle that runs in time poly(d/\\epsilon). I will
  also describe how this machinery strikes a fortune and helps in obtaining
  a tester for all planar properties which runs in time exp(d/epsilon^2). T
 his is easily obtained by a better error analysis on the seminal result of
  Newman and Sohler [SICOMP 2013].\nBased on Joint works with Sabyasachi Ba
 su\, C. Seshadhri and Andrew Stolman.\n
URL:https://www.tcs.tifr.res.in/web/events/1245
DTSTART;TZID=Asia/Kolkata:20221018T160000
DTEND;TZID=Asia/Kolkata:20221018T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1246
DTSTAMP:20230914T125956Z
SUMMARY:Total-payoff games on graphs with windows
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nWe look at a two-player ga
 me played on a weighted directed graph. The game begins by placing a pawn 
 on a vertex in the graph. The players then take turns moving the pawn to a
 n adjacent vertex in the graph\, yielding an infinite walk in the graph. E
 ach time an edge is traversed\, Player 1 receives a payoff equal to the we
 ight of the edge. An objective that has been traditionally studied for suc
 h games is the total-payoff objective.\nIn this objective\, Player 1 wins 
 the game if the total payoff that they receive in the long run is non-nega
 tive\, whereas Player 2 wins if the total-payoff is negative.\nA drawback 
 of this objective is that Player 1 may win the game\, and yet there may ex
 ist arbitrarily long stretches in the play in which the total-payoff is ne
 gative. This leads us to consider a stronger\nobjective: window total-payo
 ff. In this objective\, Player 1 wins if from every point in the play\, th
 ey can ensure that the total-payoff becomes non-negative in at most L step
 s. This objective gives stronger guarantees on the payoff received by Play
 er 1 while at the same time being easier to compute.  Computing the winni
 ng regions and winning strategies for the players for the traditional tota
 l-payoff objective is only known to be in NP \\cap coNP\, whereas we see p
 olynomial time algorithms to compute the same for the window total-payoff 
 objective.\nAll results presented in this talk are from the paper “Looki
 ng at mean-payoff and total-payoff through windows” by Chatterjee\, Doye
 n\, Randour\, and Raskin (2015).\n
URL:https://www.tcs.tifr.res.in/web/events/1246
DTSTART;TZID=Asia/Kolkata:20221021T140000
DTEND;TZID=Asia/Kolkata:20221021T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1247
DTSTAMP:20230914T125956Z
SUMMARY:Commitment over Unreliable Noisy Channels: When Awareness Meets Con
 trol
DESCRIPTION:Speaker: Manideep Mamindlapally\n\nAbstract: \nWe study commitm
 ents over unreliable compound noisy channels\, where parties may know the 
 compound channel state but lack control over that state. Commitment is one
  of the common building blocks for many cryptographic protocols which real
 ize multi-party computational functionalities in a secure manner. A noisy 
 channel\, among others\, is widely acknowledged as a promising resource fo
 r realizing information-theoretically secure cryptographic primitives\, in
 cluding commitment. However\, unreliable noisy channels with poorly or imp
 recisely characterized statistical behaviour can severely degrade commitme
 nt guarantees. Our focus is unreliability on account of a compound channel
  state\, albeit under public awareness of that state. Building on prior wo
 rk\, we seek to characterize the optimal commitment throughput or commitme
 nt capacity of compound binary symmetric channels when parties may be stat
 e-aware. State-awareness implies a passive and publicly known capability o
 f precise channel knowledge (whether said party is honest or dishonest)\; 
 however\, state-awareness precludes any active and private channel state c
 ontrol as in\, for instance\, the classic unfair noisy channels (UNCs). We
  present new results on the commitment capacity under all possible configu
 rations where individual parties may (or may not) be state-aware. An impor
 tant takeaway of our work is the following: even a fairly weak capability 
 of state-awareness (albeit when asymmetric and only at the committer-side)
  can degrade the commitment throughput to the same extent as under strongl
 y capable parties that can privately control the compound state.\n
URL:https://www.tcs.tifr.res.in/web/events/1247
DTSTART;TZID=Asia/Kolkata:20221028T150000
DTEND;TZID=Asia/Kolkata:20221028T160000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1248
DTSTAMP:20230914T125956Z
SUMMARY:Logic is not logic
DESCRIPTION:Speaker: Jean-Yves Beziau (Federal University of Rio de Janeiro
 \, Brazil.)\n\nAbstract: \nLogic is an important field of research with ma
 ny aspects. In this talk we will discuss in particular the difference betw
 een logic as reasoning and logic as a theory about reasoning.  In the ligh
 t of this distinction we will examine  the unfolding of logic into logic a
 nd metalogic\, the proliferation of logic systems\, the question  of the r
 elativity and the universality of logic and the place and interaction of l
 ogic with regards to other sciences such as  mathematics\, semiotics and c
 omputer science.  \n\nShort bio:\nJean-Yves Beziau is a Swiss Logician\, P
 hilosopher and Mathematician\, PhD in mathematics and PhD in Philosophy. H
 e has been living and working in different places: France\, Brazil\, Polan
 d\, Corsica\, California (UCLA\, Stanford\, UCSD)\, Switzerland. He is cur
 rently Professor at the University of Brazil in Rio de Janeiro\, former Di
 rector of Graduate Studies in Philosophy and former President of the Brazi
 lian Academy of Philosophy.\nHe is the creator of the World Logic Day\, ye
 arly celebrated on January 14 (UNESCO international days)\, the World Logi
 c Prizes Contest\, the founder and Editor-in-Chief of the journal Logica U
 niversalis  and South American Journal of Logic\, the book series Logic Ph
 Ds\,  Studies in Universal Logic and area logic editor of the Internet Enc
 yclopedia of Philosophy.   He has published about 200 research papers and 
 30 edited books and Special Issues of Journals. He has also organized many
  events around the world\, having launched in particular four series of Wo
 rld Congresses.\n
URL:https://www.tcs.tifr.res.in/web/events/1248
DTSTART;TZID=Asia/Kolkata:20221101T160000
DTEND;TZID=Asia/Kolkata:20221101T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1249
DTSTAMP:20230914T125956Z
SUMMARY:Best arm identification in the fixed confidence setting
DESCRIPTION:Speaker: Anirban Bhattacharjee\n\nAbstract: \nMulti-armed bandi
 ts are sequential decision-making problems represented as a collection of 
 probability distributions that one can sample from at every time step. One
  way to approach bandit problems is with the target of minimizing the expe
 cted regret (penalty for not sampling from the distribution with the highe
 st mean)\, given a fixed number of times that one can draw samples from th
 is distribution (called the sampling budget). The second way of approachin
 g these problems is with the target of minimizing the expected number of t
 imes these distributions need to be sampled from (called the sampling comp
 lexity)\, in order to declare the "best arm" with reasonable certainty\, g
 iven the extent of certainty that is desired. We shall look at the "best a
 rm" approach to multi-armed bandits when all the probability distributions
  belong to a single parameter exponential family\, the lower bound on the 
 sampling complexity\, and how this lower bound may be asymptotically met.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1249
DTSTART;TZID=Asia/Kolkata:20221104T160000
DTEND;TZID=Asia/Kolkata:20221104T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1250
DTSTAMP:20230914T125956Z
SUMMARY:Maximally Recoverable Codes for Distributed Storage Systems
DESCRIPTION:Speaker: Lalitha Vadlamani (IIIT Hyderabad)\n\nAbstract: \nIn a
  distributed storage system\, due to increase of storage capacity of a nod
 e\, efficient repair of failed nodes is becoming increasingly important in
  addition to ensuring a given level of reliability and low storage overhea
 d. Codes with locality are a class of codes designed for storage systems w
 hich have the characteristic that they trade off repair locality (number o
 f nodes accessed to repair a failed node) for storage overhead.\n\nMaximal
 ly recoverable codes are a class of codes which correct maximum possible n
 umber of erasure patterns\, given the locality constraints of the code and
  hence of interest. Two classes of maximally recoverable codes (MRC) based
  on the topology of the local parities will be introduced (i) MRC with hie
 rarchical locality (ii) MRCs with product topologies. For the case of MRC 
 with hierarchical locality\, we will present explicit constructions for al
 l parameters and field size bounds. For the case of MRCs with product topo
 logies\, we describe a certain regularity condition necessary for the eras
 ure patterns to be recoverable. Also\, we establish a connection between t
 he regularity condition and a complete matching in a suitably constructed 
 bipartite graph. This is joint work with D. Shivakrishna\, Aaditya M. Nair
 \, V. Arvind Rameshwar and Birenjith Sasidharan.\nBio: Lalitha Vadlamani r
 eceived the B.E. degree in electronics and communication engineering from 
 Osmania University\, Hyderabad\, in 2003\, and the M.E. and Ph.D. degrees 
 from the Indian Institute of Science (IISc)\, Bengaluru\, in 2005 and 2015
 \, respectively.  Since May 2015\, she has been working as an Assistant P
 rofessor with IIIT Hyderabad\, where she is currently with the Signal Proc
 essing and Communications Research Center. Her research interests include 
 coding for distributed storage and computing\, index coding\, polar codes\
 , learning-based codes and coded blockchains. She was a recipient of Prof.
  I. S. N. Murthy medal from IISc in 2005\, and the TCS Research Scholarshi
 p for the year 2011. Her article won the runner up best paper award at NCC
  2019.\n
URL:https://www.tcs.tifr.res.in/web/events/1250
DTSTART;TZID=Asia/Kolkata:20221111T113000
DTEND;TZID=Asia/Kolkata:20221111T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1251
DTSTAMP:20230914T125956Z
SUMMARY:On The Linear Arboricity Conjecture
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nA linear 
 forest is a forest in which every connected component is a line. The linea
 r arboricity of an undirected graph is the minimum t such that the edge se
 t can be partitioned into t subsets\, each of which forms a linear forest.
 \n\nHarari introduced this quantity as one of the covering invariants of g
 raphs. Harari\, Exoo and Akiyama (1981) made the following conjecture: the
  linear arboricity of any d regular graph is ceil(d+1)/2 (the lower bound 
 is easy to prove\; the non-trivial part is the upper bound).\n\nAlon prove
 d in 1988 that the linear arboricity of a d regular graph is at most d/2 +
  O(d^{3/4+\\epsilon}) for any $\\epsilon > 0$. The proof uses Lovasz Local
  Lemma and probabilistic method in very unexpected situations. We shall pr
 esent this proof.\n\nLink to paper: https://link.springer.com/article/10.1
 007/BF02783300\n
URL:https://www.tcs.tifr.res.in/web/events/1251
DTSTART;TZID=Asia/Kolkata:20221111T160000
DTEND;TZID=Asia/Kolkata:20221111T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1252
DTSTAMP:20230914T125956Z
SUMMARY:The Role of Adaptivity in Learning and Decision-Making
DESCRIPTION:Speaker: Arpit Agarwal (Columbia University)\n\nAbstract: \nIn 
 many machine learning applications the learner is faced with a *stochastic
  environment* and it (sequentially) probes or influences the environment s
 o as to optimize a given objective function. Examples of such applications
  include recommendation systems\, web advertising\, viral marketing\, clin
 ical trials\, search ranking etc. For instance\, in recommendation systems
 \, the learner attempts to identify good recommendations by probing the st
 ochastic preferences of users. Similarly\, in viral marketing\, the learne
 r attempts to spread information through a social network using marketing 
 campaigns that influence (stochastic) subsets of the network.\n\nMost exis
 ting learning algorithms for these applications operate in one of two sett
 ings: (1) non-adaptive\, and (2) fully adaptive. In the non-adaptive setti
 ng\, all the selections/probes are completely determined ahead of time. Ho
 wever\, these a priori selections might be inefficient as some of them mig
 ht be unnecessary in hindsight. In the fully adaptive setting\, the select
 ion policy is updated after each observation from the environment. However
 \, this fully adaptive setting might not be practical in many applications
  due to delays in receiving observations from many parallel sources. In th
 is talk we introduce a semi-adaptive setting that interpolates between the
 se two extreme settings for a wide range of learning and decision-making p
 roblems such as best arm identification in multi-armed bandits\, ranking f
 rom pairwise comparisons\, dueling bandits\, and stochastic submodular max
 imization. We show that semi-adaptive policies enjoy the power of fully ad
 aptive policies while requiring very few updates to the selection/probing 
 rules. We also identify the trade-offs between rounds of adaptivity and pe
 rformance.\n\nBio: Dr. Arpit Agarwal is a Postdoctoral Research Fellow at 
 the Data Science Institute at Columbia University. His research interests 
 primarily lie in machine learning\, with connections to algorithmic econom
 ics and theoretical computer science. Before joining Columbia\, he receive
 d a Ph.D. in Computer Science from the University of Pennsylvania and a ma
 sters in Computer Science from the Indian Institute of Science.\n
URL:https://www.tcs.tifr.res.in/web/events/1252
DTSTART;TZID=Asia/Kolkata:20221114T160000
DTEND;TZID=Asia/Kolkata:20221114T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1253
DTSTAMP:20230914T125956Z
SUMMARY:How to Simulate it?
DESCRIPTION:Speaker: Manideep Mamindlapally (STCS\, TIFR\, Mumbai.)\n\nAbst
 ract: \nThe notion of security for multi-party computations is not absolut
 ely defined. Simulation is a technique that models an abstract "ideal worl
 d" where a desired multi-party functionality is computed\, and is secure b
 y definition. Then in the "real world" you would execute any given interac
 tive protocol between agents\, who could be honest or cheating. You would 
 then argue that the outputs are similar to those of the secure "ideal worl
 d"\, and in doing so prove that the protocol itself is secure. In this sem
 inar\, I will talk about some such simulation proof techniques for some co
 mmon multi-party computation problems - oblivious transfer and the zero-kn
 owledge proof for the 3-colouring graph problem - based on examples from a
  tutorial by Yehuda Lindell.\n
URL:https://www.tcs.tifr.res.in/web/events/1253
DTSTART;TZID=Asia/Kolkata:20221125T160000
DTEND;TZID=Asia/Kolkata:20221125T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1254
DTSTAMP:20230914T125956Z
SUMMARY:Median voter theorem and Why it Fails in Practice
DESCRIPTION:Speaker: Soumyajit Pyne\n\nAbstract: \nThe Median Voter Theorem
  (MVT) is a cornerstone of modern political science theory. It states that
  in a single peaked preference profile\, the top choice of the median vote
 r is the Condorcet winner. So\, the dominant strategy for a candidate is t
 o be the top choice of the median voter. However in practice\, often the m
 edian voter's top choice is not the winner. To understand this we will go 
 through the paper "Polarization\, abstention\, and the median voter theore
 m" - by Fu\, Sirianni\, Jones. Later I will show some generalization of th
 e model used in that paper and analyze some computational aspects of that 
 model.\n
URL:https://www.tcs.tifr.res.in/web/events/1254
DTSTART;TZID=Asia/Kolkata:20221202T160000
DTEND;TZID=Asia/Kolkata:20221202T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1255
DTSTAMP:20230914T125956Z
SUMMARY:Bandits with Heavy Tails: Algorithms\, Analysis and Optimality
DESCRIPTION:Speaker: Shubhada Agrawal\n\nAbstract: \nMulti-armed bandit (MA
 B) is a popular framework for sequential decision-making in an uncertain e
 nvironment. In the classical setup of MAB\, the algorithm has access to a 
 fixed and finite set K of unknown\, independent probability distributions 
 or arms. At each time step\, having observed the outcomes of all the previ
 ous actions\, the algorithm chooses one of the K arms and receives an inde
 pendent sample drawn from the underlying distribution\, which may be consi
 dered a reward. The algorithm's goal is either to maximize the accumulated
  rewards or to identify the best arm in as few samples as possible for an 
 appropriate notion of best.\nVariants of these classical formulations have
  been widely studied in the literature. Tight lower bounds and optimal alg
 orithms have been developed under the assumption that the arm distribution
 s are either Sub-Gaussian or come from a single parameter exponential fami
 ly (SPEF)\, for example\, Gaussian distributions with a known variance or 
 Bernoulli distributions. However\, in practice\, these distributional assu
 mptions may not hold. Developing lower bounds and optimal algorithms for t
 he general distributions largely remained open\, mainly because of the nee
 d for new tools for the analysis in this generality.\nIn this dissertation
 \, we undertake a detailed study of the MAB problems allowing for all the 
 distributions with a known uniform bound on their (1+\\epsilon)^{th} momen
 ts for some $\\epsilon > 0$. This class subsumes a large class of heavy-ta
 iled distributions. We develop a framework with essential tools and concen
 tration inequalities and use it to design optimal algorithms for three key
  variants of the MAB problem\, including the classical frameworks of regre
 t minimization and best-arm identification.\nA key component of designing 
 an optimal algorithm for MAB is constructing tight\, anytime valid confide
 nce intervals (CIs) for mean. We develop new concentration inequalities to
  this end\, which may be of independent interest.\nThe above results were 
 obtained in collaborations involving Sandeep Juneja\, Wouter M. Koolen and
  Peter Glynn.\n\nZoom link: https://zoom.us/j/94294491152?pwd=MUZiNkk5Sy9
 2Z3VEc3laZUNCTGdDdz09\n
URL:https://www.tcs.tifr.res.in/web/events/1255
DTSTART;TZID=Asia/Kolkata:20221209T113000
DTEND;TZID=Asia/Kolkata:20221209T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1256
DTSTAMP:20230914T125956Z
SUMMARY:Demystifying Approximate Reinforcement Learning Algorithms that use
  epsilon-greedy Exploration
DESCRIPTION:Speaker: Aditya Gopalan (Indian Institute of Science (IISc)\nBe
 ngaluru)\n\nAbstract: \nIn reinforcement learning\, value-function methods
  such as Q-learning and SARSA(0) with $\\epsilon$-greedy exploration are a
 mong the state of the art\, and their tabular (exact) forms converge to th
 e optimal Q-function under reasonable conditions. However\, with function 
 approximation\, these methods are known to exhibit strange behaviors\, e.g
 .\, policy oscillation and chattering\, convergence to different attractor
 s (possibly even the worst policy) on different runs\, etc.\, apart from t
 he well-known instability of iterates. Accordingly\, a theory to explain t
 hese phenomena has been a long-standing open problem\, even for basic line
 ar function approximation (Sutton\, 1999). Our work uses differential incl
 usion theory to provide the first framework for resolving this problem. We
  further illustrate via numerical examples how this framework helps comple
 tely explain these algorithms' asymptotic behaviors. (Joint work with Guga
 n Thoppe\, IISc)\n
URL:https://www.tcs.tifr.res.in/web/events/1256
DTSTART;TZID=Asia/Kolkata:20221209T143000
DTEND;TZID=Asia/Kolkata:20221209T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1257
DTSTAMP:20230914T125956Z
SUMMARY:Information Freshness for Monitoring and Control over Wireless Netw
 orks
DESCRIPTION:Speaker: Vishrant Tripathi (Massachusetts Institute of Technolo
 gy (MIT))\n\nAbstract: \nI will motivate information freshness as an essen
 tial ingredient for performing monitoring and control tasks over wireless 
 networks. To this end\, I will introduce the notion of Age-of-Information 
 (AoI) which has become popular in networking literature over the past deca
 de. I will show that networked monitoring and control can be viewed as equ
 ivalent AoI optimization problems\, and discuss how to solve these problem
 s in single and multi hop networks. Next\, I will discuss learning of AoI 
 cost functions (when the mapping between system performance and informatio
 n freshness is unknown and time-varying). For the final part of the talk\,
  I will discuss WiSwarm - a wireless system for communication between mult
 iple UAVs and a central base station - that brings our ideas from theory t
 o the real world.\n
URL:https://www.tcs.tifr.res.in/web/events/1257
DTSTART;TZID=Asia/Kolkata:20221219T160000
DTEND;TZID=Asia/Kolkata:20221219T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1258
DTSTAMP:20230914T125956Z
SUMMARY:Almost linear time algorithms for max-flow and more
DESCRIPTION:Speaker: Sushant Sachdeva (University of Toronto)\n\nAbstract: 
 \nWe give the first almost-linear time algorithm for computing exact maxim
 um flows and minimum-cost flows on directed graphs. By well known reductio
 ns\, this implies almost-linear time algorithms for several problems inclu
 ding bipartite matching\, optimal transport\, and undirected vertex connec
 tivity.\n\nOur algorithm is designed using a new Interior Point Method (IP
 M) that builds the flow as a sequence of almost-linear number of approxima
 te undirected minimum-ratio cycles\, each of which is computed and process
 ed very efficiently using a new dynamic data structure.\n\nOur framework e
 xtends to give an almost-linear time algorithm for computing flows that mi
 nimize general edge-separable convex functions to high accuracy. This give
 s the first almost-linear time algorithm for several problems including en
 tropy-regularized optimal transport\, matrix scaling\, p-norm flows\, and 
 Isotonic regression.\n\nJoint work with Li Chen\, Rasmus Kyng\, Yang Liu\,
  Richard Peng\, and Maximilian Probst Gutenberg.\n\nBio: Sushant Sachdeva 
 is a faculty member at the CS dept. at the University of Toronto and a Vec
 tor Institute affiliate. He is interested in algorithms\, and its connecti
 ons to optimization\, machine learning\, and statistics. His recent resear
 ch focus has been the design of fast algorithms for graph problems. https:
 //www.cs.toronto.edu/~sachdeva/\n
URL:https://www.tcs.tifr.res.in/web/events/1258
DTSTART;TZID=Asia/Kolkata:20221222T143000
DTEND;TZID=Asia/Kolkata:20221222T153000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1259
DTSTAMP:20230914T125956Z
SUMMARY:The Kikuchi Matrix Method
DESCRIPTION:Speaker: Pravesh Kothari (Carnegie Mellon University)\n\nAbstra
 ct: \nIn this talk\, I will present a new method that reduces understandin
 g an appropriate notion of girth in hypergraphs to unraveling the spectrum
  of a "Kikuchi" matrix associated with the hypergraph. I will discuss thre
 e applications of this technique: 1. Finding a refutation algorithm for sm
 oothed instances of constraint satisfaction problems (obtained by randomly
  perturbing the literal patterns in a worst-case instance with a small pro
 bability) that matches the best running-time vs constraint-density trade-o
 ffs for the significantly special and easier case of random CSPs\, 2. Conf
 irming Feige's 2008 Conjecture that postulated an extremal girth vs densit
 y trade-off (a.k.a. Moore bounds) for k-uniform hypergraphs that generaliz
 es the Alon-Hoory-Linial Moore bound for graphs\, 3. Proving a cubic lower
  bound on the block length of 3 query locally decodable codes improving on
  the prior best quadratic lower bound from the early 2000s. Based on joint
  works with Omar Alrabiyah (Berkeley)\, Tim Hsieh (CMU)\, Peter Manohar (C
 MU)\, Sidhanth Mohanty (Berkeley)\, and Venkat Guruswami (Berkeley).\n
URL:https://www.tcs.tifr.res.in/web/events/1259
DTSTART;TZID=Asia/Kolkata:20221223T113000
DTEND;TZID=Asia/Kolkata:20221223T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1260
DTSTAMP:20230914T125956Z
SUMMARY:Heterogeneous arrival streams in a two-queue network
DESCRIPTION:Speaker: Agniv Bandyopadhyay\n\nAbstract: \nIn a concert queuin
 g game\, users decide when to arrive at a bottleneck queue of constant cap
 acity that opens at a specific time. Every user wants to simultaneously mi
 nimize her waiting time and get served as early as possible. In previous i
 ncarnations\, this game has been studied over a single queue and over netw
 orks with specific topologies such as tandem networks\, trellis networks\,
  and general feed-forward networks having multiple layers\, with users arr
 iving at one extreme layer and traveling to the other extreme. A unique no
 n-cooperative Nash Equilibrium profile has been identified in the case of 
 the single queue and tandem networks with multiple layers. Whereas for tre
 llis networks and general feed-forward networks\, the existence of non-coo
 perative Nash Equilibrium profiles has been proved. It has also been prove
 n that if there are multiple such equilibriums\, they will all have an equ
 al social cost. In this project\, we attempt to study the situation where 
 multiple classes of players are traveling through different paths in a que
 uing network. For simplicity\, we consider two groups of players who inten
 d to travel on two distinct paths in a two-queue network. We also assume t
 hat all players in a group have identical preferences. In all these instan
 ces\, we can find a unique non-cooperative Nash Equilibrium profile as lon
 g as the two groups have different preferences. Also\, in equilibrium\, th
 e two groups will choose their order of arrival depending on how their pop
 ulation sizes compare. We also observe that whenever the two groups share 
 one queue in their path\, if the queue's capacity is under an identified t
 hreshold\, the two groups will arrive in that queue in contiguous disjoint
  intervals. On the other hand\, if it is strictly above that threshold\, t
 he two groups will arrive together in that queue over some contiguous inte
 rval in the equilibrium profile.\n
URL:https://www.tcs.tifr.res.in/web/events/1260
DTSTART;TZID=Asia/Kolkata:20221223T160000
DTEND;TZID=Asia/Kolkata:20221223T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1261
DTSTAMP:20230914T125956Z
SUMMARY:Convex influences and a quantitative Gaussian correlation inequalit
 y
DESCRIPTION:Speaker: Anindya De (University of Pennsylvania)\n\nAbstract: \
 nThe Gaussian correlation inequality (GCI)\, proven by Royen in 2014\,  st
 ates that any two centrally symmetric convex sets (say K and L) in the Gau
 ssian space are positively correlated. We will prove a new quantitative ve
 rsion of the GCI which gives a lower bound on this correlation based on th
 e "common influential directions" of K and L. This can be seen as a Gaussi
 an space analogue of Talagrand's well known correlation inequality for mon
 otone functions. To obtain this inequality\, we propose a new approach\, b
 ased on analysis of Littlewood type polynomials\, which gives a recipe to 
 transfer qualitative correlation inequalities into quantitative correlatio
 n inequalities. En route\, we also give a new notion of influences for con
 vex symmetric sets over the Gaussian space which has many of the propertie
 s of influences from Boolean functions over the discrete cube. Much remain
 s to be explored\, in particular\, about this new notion of influences for
  convex sets.\n\nBased on joint work with Shivam Nadimpalli and Rocco Serv
 edio.\n
URL:https://www.tcs.tifr.res.in/web/events/1261
DTSTART;TZID=Asia/Kolkata:20221227T160000
DTEND;TZID=Asia/Kolkata:20221227T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1262
DTSTAMP:20230914T125957Z
SUMMARY:Communication With Adversary Identification in Byzantine Multiple A
 ccess Channels
DESCRIPTION:Speaker: Neha Sangwan\n\nAbstract: \nWe introduce the problem o
 f determining the identity of a byzantine user (internal adversary) in a c
 ommunication system. We consider a two-user discrete memoryless multiple a
 ccess channel where either user may deviate from the prescribed behaviour.
  Owing to the noisy nature of the channel\, it may be overly restrictive t
 o attempt to detect all deviations. In our formulation\, we only require d
 etecting deviations which impede the decoding of the non-deviating user's 
 message. When neither user deviates\, correct decoding is required. When o
 ne user deviates\, the decoder must either output a pair of messages of wh
 ich the message of the non-deviating user is correct or identify the devia
 ting user. The users and the receiver do not share any randomness. The res
 ults include a characterization of the set of channels where communication
  is feasible\, and an inner and outer bound on the capacity region.\n \nTh
 is is based on a joint work with Mayank Bakshi\, Bikash Kumar Dey and Vino
 d M. Prabhakaran\, and was presented at ISIT\, 2021.\n
URL:https://www.tcs.tifr.res.in/web/events/1262
DTSTART;TZID=Asia/Kolkata:20221230T170000
DTEND;TZID=Asia/Kolkata:20221230T180000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1263
DTSTAMP:20230914T125957Z
SUMMARY:Private Optimization and Statistical Physics: Low-Rank Matrix Appro
 ximation
DESCRIPTION:Speaker: Nisheeth Vishnoi (Yale university)\n\nAbstract: \nIn t
 his talk\, I will discuss the following connections between private optimi
 zation and statistical physics in the context of the low-rank matrix appro
 ximation problem:\n1) An efficient algorithm to privately compute a low-ra
 nk approximation and how it leads to an efficient way to sample from Haris
 h-Chandra-Itzykson-Zuber densities studied in physics and mathematics\, an
 d\n2) An improved analysis of the "utility" of the  "Gaussian Mechanism" 
 for private low-rank approximation using Dyson Brownian motion.\n
URL:https://www.tcs.tifr.res.in/web/events/1263
DTSTART;TZID=Asia/Kolkata:20230103T140000
DTEND;TZID=Asia/Kolkata:20230103T150000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1264
DTSTAMP:20230914T125957Z
SUMMARY:Classical Verification of Quantum Computations
DESCRIPTION:Speaker: Manideep Mamindlapally (TIFR\, Mumbai.)\n\nAbstract: \
 nQuantum computers are in general believed to be more powerful than classi
 cal computers\, but it is not clear if they are powerful enough to solve p
 roblems that a classical computer can’t even verify. Are there any tasks
  which a malicious quantum agent can solve and claim an answer that go unc
 hecked by classical parties? There were several attempts to find the answe
 r to this question. In this talk\, I will discuss a recent development whi
 ch was the discovery of a protocol for a classical computer to efficiently
  verify the results of any efficient quantum computation by Urmila Mahadev
 .\n
URL:https://www.tcs.tifr.res.in/web/events/1264
DTSTART;TZID=Asia/Kolkata:20230106T160000
DTEND;TZID=Asia/Kolkata:20230106T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1265
DTSTAMP:20230914T125957Z
SUMMARY:Scaling limits of stochastic optimization algorithms over large gra
 phs
DESCRIPTION:Speaker: Raghav Somani (University of Washington)\n\nAbstract: 
 \nWasserstein gradient flows often arise from mean-field interactions amon
 g exchangeable particles. In many interesting applications however\, the "
 particles" are edge weights in a graph whose vertex labels are exchangeabl
 e but not the edges themselves. Motivated by such graph optimization probl
 ems we investigate the question of optimization of functions over this dif
 ferent class of symmetries. Popular applications include training of large
  computational graphs like (Deep) Neural Networks. This body of work shows
  that discrete stochastic optimization algorithms over finite graphs have 
 a well-defined analytical scaling limit as the size of the network grows t
 o infinity. The limiting space is that of graphons\, a notion introduced b
 y Lovász and Szegedy to describe limits of dense graph sequences. The lim
 iting curves are given by a novel notion of McKean-Vlasov equations on gra
 phons and a corresponding notion of propagation of chaos holds. In the asy
 mptotically zero-noise case\, the limit is a gradient flow on the metric s
 pace of graphons. This is an attempt to generalize the Wasserstein calculu
 s to higher-order exchangeable structures.\n
URL:https://www.tcs.tifr.res.in/web/events/1265
DTSTART;TZID=Asia/Kolkata:20230117T160000
DTEND;TZID=Asia/Kolkata:20230117T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1266
DTSTAMP:20230914T125957Z
SUMMARY:A survey on finding Kings in tournaments
DESCRIPTION:Speaker: Arghya Chakraborty\n\nAbstract: \nIn any tournament be
 tween several participants\, transitivity is sometimes not satisfied (i.e.
  A may defeat B\, B defeats C and C in turn defeats A). In any case\, we s
 hall have to define a winner. We shall first define the notion of a 'king'
  in a tournament graph and then show that one can find a king by organizin
 g O(n^{3/2}) matches when there are n participants. Also\, we shall show t
 hat at least \\Omega(n^{4/3}) matches need to be organized in the worst ca
 se.\n \nThe results that I will go over are mostly from https://epubs.siam
 .org/doi/abs/10.1137/S0097539702410053.\n
URL:https://www.tcs.tifr.res.in/web/events/1266
DTSTART;TZID=Asia/Kolkata:20230120T160000
DTEND;TZID=Asia/Kolkata:20230120T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1267
DTSTAMP:20230914T125957Z
SUMMARY:A constant lower bound for the union-closed sets conjecture
DESCRIPTION:Speaker: Dr. Justin Gilmer (Google Brain)\n\nAbstract: \nI will
  introduce Frankl's. conjecture\, discuss prior approaches and why it is a
  bit notorious. Then will discuss an information-theoretic approach that e
 stablishes a constant lower bound for the maximum element frequency in uni
 on-closed families of sets.\n
URL:https://www.tcs.tifr.res.in/web/events/1267
DTSTART;TZID=Asia/Kolkata:20230124T093000
DTEND;TZID=Asia/Kolkata:20230124T103000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1268
DTSTAMP:20230914T125957Z
SUMMARY:Estimating the size of union of sets in streaming model
DESCRIPTION:Speaker: Sourav Chakraborty (ISI Kolkata)\n\nAbstract: \nWe pre
 sent a very simple and efficient sampling-based algorithm for estimating t
 he union of sets in the streaming setting. Suppose we have a collection of
  sets S_1\, . . . \, S_M subsets of T\, arriving one by one in a stream\; 
 the sets are not given explicitly to us but rather defined implicitly via 
 the following oracles: for each set\, we can know the size of the set\, ge
 t a uniform sample from the set\, and given a point check whether it belon
 gs to the set. The goal is to estimate the size of the union of the sets S
 _1\, . . . \, S_M.\nWe present a simple algorithm that estimates the size 
 of the union\, upto a (1 + \\epsilon) factor\, in space complexity and upd
 ate time complexity O(log(M)^2/\\epsilon^2).\nOur algorithm provides the f
 irst algorithm with polynomial dependence on the dimension for Klee’s me
 asure problem in streaming setting and independent of the stream size\, th
 ereby settling the open problem of Woodruff and Tirthpura (PODS-12).\nThis
  talk will be based on works with Kuldeep Meel and Vinodchandran (PODS21\,
  PODS22 and ESA22).\n
URL:https://www.tcs.tifr.res.in/web/events/1268
DTSTART;TZID=Asia/Kolkata:20230127T160000
DTEND;TZID=Asia/Kolkata:20230127T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1269
DTSTAMP:20230914T125957Z
SUMMARY:An Approximate Generalization of the Okamura-Seymour Theorem
DESCRIPTION:Speaker: Nikhil Kumar (Hasso-Plattner institute\, Potsdam\, Ger
 many.)\n\nAbstract: \nWe consider the problem of multicommodity flows in p
 lanar graphs. Okamura and Seymour showed that if all the demands are incid
 ent on one face\, then the cut-condition is sufficient for routing demands
 . We consider the following generalization of this setting and prove an ap
 proximate max flow-min cut theorem: for every demand edge\, there exists a
  face containing both its end points. We show that the cut-condition is su
 fficient for routing Ω(1) -fraction of all the demands. To prove this\, w
 e give a L1-embedding of the planar metric which approximately preserves d
 istance between all pair of points on the same face.\n
URL:https://www.tcs.tifr.res.in/web/events/1269
DTSTART;TZID=Asia/Kolkata:20230131T093000
DTEND;TZID=Asia/Kolkata:20230131T103000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1270
DTSTAMP:20230914T125957Z
SUMMARY:The Moore Bound for Irregular Graphs
DESCRIPTION:Speaker: Shanthanu  Suresh Rai\n\nAbstract: \nWhat is the large
 st number of edges in a graph of order n and girth g? For d-regular graphs
 \, essentially the best known answer is provided by the Moore bound. This 
 result can be extended to cover irregular graphs as well.\n\nIn the talk\,
  we will look at what the Moore bound is and some problems related to Moor
 e graphs. Then we will try to generalize the Moore bound for irregular gra
 phs.\n\nPaper: https://link.springer.com/article/10.1007/s003730200002\n
URL:https://www.tcs.tifr.res.in/web/events/1270
DTSTART;TZID=Asia/Kolkata:20230203T160000
DTEND;TZID=Asia/Kolkata:20230203T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1271
DTSTAMP:20230914T125957Z
SUMMARY:A THEORETICALLY TRACTABLE CROSS VALIDATION FRAMEWORK FOR SIGNAL DEN
 OISING
DESCRIPTION:Speaker: Sabyasachi Chatterjee (University of Ilinois at Urbana
  Champagne)\n\nAbstract: \nWe formulate a general cross validation framewo
 rk for signal denoising. The general framework is then applied to nonparam
 etric regression methods such as Trend Filtering and Dyadic CART. The resu
 lting cross validated versions are then shown to attain nearly the same ra
 tes of convergence as are known for the optimally tuned analogues. There d
 id not exist any previous theoretical analyses of cross validated versions
  of Trend Filtering or Dyadic CART. Our general framework is inspired by t
 he ideas in Chatterjee and Jafarov (2015) and is potentially applicable to
  a wide range of estimation methods which use tuning parameters. BIO: Saby
 asachi Chatterjee is an Assistant Professor (from 2017 onwards) in the Sta
 tistics Department at University of Illinois at Urbana Champaign. Most of 
 his research has been in Statistical Signal Processing. His is also intere
 sted in Probability and all theoretical aspects of Machine Learning. He ob
 tained his Phd in 2014 at Yale University and then was a Kruskal Instructo
 r at University of Chicago till 2017.\n
URL:https://www.tcs.tifr.res.in/web/events/1271
DTSTART;TZID=Asia/Kolkata:20230210T140000
DTEND;TZID=Asia/Kolkata:20230210T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1272
DTSTAMP:20230914T125957Z
SUMMARY:A visual proof of Fermat's two square theorem
DESCRIPTION:Speaker: Malhar Ajit  Managoli\n\nAbstract: \nFermat's two squa
 re theorem states that: \nAn odd prime p can be written as a sum of two sq
 uares if and only if p = 1 (mod 4) \nFurthermore\, such a solution is uniq
 ue. Many proofs have been given of this fact\, but most of them are very t
 ricky. \nA relatively simple proof of the existence part  appeared in a su
 rvey of proofs of Fermat's theorem by Alexander Spivak\, where the key poi
 nt is presented in a visual manner\, which I will present. The proof of un
 iqueness is much simpler\, and I will present it\, time permitting.\n
URL:https://www.tcs.tifr.res.in/web/events/1272
DTSTART;TZID=Asia/Kolkata:20230210T160000
DTEND;TZID=Asia/Kolkata:20230210T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1273
DTSTAMP:20230914T125957Z
SUMMARY:A Chernoff-Stein Lemma for adversarial hypothesis testing
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nIn the composite hypothesi
 s testing setting\, the detector receives n i.i.d. samples either from a d
 istribution  p∈P or from a distribution q∈Q. It then decides the corr
 ect set from which the samples were drawn.\nBrandao\, Harrow\, Lee and Per
 es [BHLP] considered an adaptive generalization of this problem where the 
 choice of p∈P and q∈Q can change in each sample in some way that depen
 ds arbitrarily on the previous samples. Initially\, one might think that t
 his might confuse the detector and worsen the optimal error exponent. But\
 , [BHLP] showed that the exponent remains the same and a simple maximum li
 kelihood ratio test achieves it.\nLink to the paper: https://arxiv.org/abs
 /1308.6702\n
URL:https://www.tcs.tifr.res.in/web/events/1273
DTSTART;TZID=Asia/Kolkata:20230217T160000
DTEND;TZID=Asia/Kolkata:20230217T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1274
DTSTAMP:20230914T125957Z
SUMMARY:Computational variants of the general Lax conjecture
DESCRIPTION:Speaker: Rafael Oliviera (University of Waterloo)\n\nAbstract: 
 \nHyperbolicity cones are convex semialgebraic sets generalizing both poly
 hedral and spectrahedral cones\, the latter forming the basic geometric se
 ts from linear and semidefinite programming. Hyperbolic polynomials\, whic
 h give rise to these hyperbolicity cones\, have recently found application
 s in several areas of mathematics\, statistical physics\, computer science
 \, and optimization. The general Lax conjecture is a fundamental question 
 in real algebraic geometry and optimization: do hyperbolicity cones form a
  strict generalization of spectrahedral cones?\nIn this talk\, we will giv
 e an introduction to hyperbolic polynomials and their cones\, and raise se
 veral computational questions related to these objects\, which blend algeb
 raic complexity\, real algebraic geometry\, proof complexity and optimizat
 ion.\n
URL:https://www.tcs.tifr.res.in/web/events/1274
DTSTART;TZID=Asia/Kolkata:20230220T143000
DTEND;TZID=Asia/Kolkata:20230220T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1275
DTSTAMP:20230921T105045Z
SUMMARY:Communication is Everything. Everything is Communication
DESCRIPTION:Speaker: Raghuvansh Saxena (Microsoft Research)\n\nAbstract: \n
 Communication complexity is the study of how two or more parties with priv
 ate inputs compute a function that depends on all their inputs. The scarce
  resource is communication\, or the number of bits exchanged between the p
 arties. What is amazing about this field is that it has applications not o
 nly in areas where there is actual communication between parties\, such as
  auction design and distributed computing\, but also in areas which superf
 icially may seem completely unrelated to communication\, such as graph str
 eaming and data structures. This is because bounds on communication can of
 ten be translated into bounds on other resources of interest\, such as mem
 ory and the number of wires.\nIn this talk\, I will cover my work in devel
 oping and applying new communication complexity tools to mechanism design\
 , streaming algorithms\, error-resilient circuits\, and interactive coding
 \, with a special focus on the latter. Specifically\, I shall cover two of
  my recent results [EKS20a] and [EKSZ22]\, that develop new codes resilien
 t to a larger fraction of noise than the previous state-of-the-art. In the
  case of [EKSZ22]\, I will also explain why our result opens a whole new p
 aradigm for error correcting codes that was previously unexplored. No prio
 r background will be assumed.\n
URL:https://www.tcs.tifr.res.in/web/events/1275
DTSTART;TZID=Asia/Kolkata:20230221T090000
DTEND;TZID=Asia/Kolkata:20230221T100000
LOCATION:Online with A-201 screening
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1276
DTSTAMP:20230914T125957Z
SUMMARY:Fair and Efficient Allocations under Sub-additive Valuations
DESCRIPTION:Speaker: Yeshwant Chandrakant  Pandit\n\nAbstract: \nFair divis
 ion of a set of resources among several agents is a commonly occurring pro
 blem in many real-world settings. In this paper\, we will study the proble
 m of allocating a set of indivisible goods among agents with sub-additive 
 valuations in a fair and efficient manner. Envy-Freeness up to any good (E
 FX) is the most compelling notion of fairness in the context of indivisibl
 e goods. Although the existence of EFX is not known beyond the simple case
  of two agents with sub-additive valuations \, some good approximations of
  EFX are known to exist\, namely 1/2-EFX allocation and EFX allocations wi
 th bounded charity.\n\nIn this talk\, we will look at a polynomial time al
 gorithm that outputs an allocation that satisfies either of the two approx
 imations of EFX as well as achieve an O(n) approximation to the Nash welfa
 re\n
URL:https://www.tcs.tifr.res.in/web/events/1276
DTSTART;TZID=Asia/Kolkata:20230224T160000
DTEND;TZID=Asia/Kolkata:20230224T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1277
DTSTAMP:20230914T125957Z
SUMMARY:Determinantal complexity of the power sum polynomial
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nWe will introduce the 
 notion of determinantal complexity\, one of the main characters in the VP 
 vs VNP question\, which is the algebraic analogue of the P vs NP question.
  We will focus on a specific polynomial - the power sum polynomial - and s
 ee proof sketches for an upper bound and a lower bound on its determinanta
 l complexity. The lower bound will be from a paper by Alper\, Bogart and V
 elasco. Prerequisites for the talk are basic linear algebra (rank\, etc) a
 nd basic calculus (partial derivatives\, chain rule\, etc). There will be 
 some usage of tools from algebraic geometry but we won't see their proofs.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1277
DTSTART;TZID=Asia/Kolkata:20230303T163000
DTEND;TZID=Asia/Kolkata:20230303T173000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1278
DTSTAMP:20230914T125957Z
SUMMARY:Determinantal complexity (part 2)
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nI will complete a coup
 le of proofs from last week's student seminar on determinantal complexity.
  I will recall the required background for the proofs. On the way\, we wil
 l learn a cute linear-algebraic fact. The talk / the proofs should be acce
 ssible even if you missed last week's seminar.\n
URL:https://www.tcs.tifr.res.in/web/events/1278
DTSTART;TZID=Asia/Kolkata:20230310T160000
DTEND;TZID=Asia/Kolkata:20230310T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1279
DTSTAMP:20230914T125957Z
SUMMARY:Errors and Correction in Cumulative Knowledge
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Paulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nSocietal accumulation of knowled
 ge is a complex\, and arguably error-prone\, process. The correctness of n
 ew units of knowledge depends not only on the correctness of the new reaso
 ning\, but also on the correctness of old units that the new one builds on
 . Left unchecked errors could completely ruin the validity of most of this
  knowledge - so there must some error-correcting going on. What are the er
 ror-corrections processes and how effective are they? In this talk\, we pr
 esent a simple probabilistic process that aims to model such accumulation 
 of knowledge and study the persistence (or lack thereof) of errors. % Our 
 model for the generation of new units of knowledge is based on the prefere
 ntial attachment growth model\, to which we additionally allow for injecti
 on of errors. Furthermore\, the process includes checks aimed at catching 
 these errors. We investigate when effects of errors persist forever in the
  system (with positive probability) and when they get rooted out completel
 y by the checking process. The two basic parameters associated with the ch
 ecking process are the {\\em probability} of conducting a check and the {\
 \em depth} of the check. We show that errors are rooted out if checks are 
 sufficiently frequent and sufficiently deep. In contrast\, shallow or infr
 equent checks are insufficient to root out errors. Based on the paper: "Is
  This Correct? Let's Check!" with Omri Ben-Eliezer\, Dan Mikulincer and El
 chanan Mossel (all at MIT).\n
URL:https://www.tcs.tifr.res.in/web/events/1279
DTSTART;TZID=Asia/Kolkata:20230314T160000
DTEND;TZID=Asia/Kolkata:20230314T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1280
DTSTAMP:20230914T125957Z
SUMMARY:The Implicit Bias of Gradient Descent on Separable Data
DESCRIPTION:Speaker: Santanu Das\n\nAbstract: \nWe examine gradient descent
  on unregularised logistic regression problems\, with homogeneous linear p
 redictors on linearly separable datasets. We show the predictor converges 
 to the direction of the max-margin (hard margin SVM) solution. The result 
 also generalizes to other monotone decreasing loss functions with an infim
 um at infinity\, to multi-class problems\, and to training a weight layer 
 in a deep network in a certain restricted setting. Furthermore\, we show t
 his convergence is very slow\, and only logarithmic in the convergence of 
 the loss itself. This can help explain the benefit of continuing to optimi
 se the logistic or cross-entropy loss even after the training error is zer
 o and the training loss is extremely small\, and\, as we show\, even if th
 e validation loss increases. Our methodology can also aid in understanding
  implicit regularisation in more complex models and with other optimisatio
 n methods.\n
URL:https://www.tcs.tifr.res.in/web/events/1280
DTSTART;TZID=Asia/Kolkata:20230317T160000
DTEND;TZID=Asia/Kolkata:20230317T173000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1281
DTSTAMP:20230914T125957Z
SUMMARY:Monte Carlo tree search with advice
DESCRIPTION:Speaker: Debraj Chakraborty (Université Libre de Bruxelles)\n\
 nAbstract: \nWe show how to combine techniques from formal methods and lea
 rning for online computation of a strategy that aims at optimizing the exp
 ected long-term reward in large systems modelled as Markov decision proces
 ses. This strategy is computed with a receding horizon and using Monte Car
 lo tree search (MCTS). We augment the MCTS algorithm with the notion of ad
 vice which guides the search in the relevant part of the tree using exact 
 methods. Such advice can be symbolically written as a logical formula and 
 computed on-the-fly using model-checking tools.\n\nWe show that the classi
 cal theoretical guarantees of the Monte Carlo tree search are still mainta
 ined after this augmentation. To lower the latency of MCTS algorithms with
  advice\, we propose to replace advice coming from exact algorithms with a
 n artificial neural network. For this purpose\, we implemented an expert i
 mitation framework to train the neural network in order to replace expert 
 advice with neural advice. To demonstrate the practical interest of our te
 chniques\, we implemented the frameworks on different systems modelled as 
 MDPs.\n
URL:https://www.tcs.tifr.res.in/web/events/1281
DTSTART;TZID=Asia/Kolkata:20230321T160000
DTEND;TZID=Asia/Kolkata:20230321T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1282
DTSTAMP:20230914T125957Z
SUMMARY:Efficiency of non-truthful auctions under auto-bidding
DESCRIPTION:Speaker: Agniv Bandyopadhyay\n\nAbstract: \nAuto-bidding is a f
 ramework of ad auctions where every advertiser can tell their long-term go
 als\, such as budget\, target return on spend (RoS)\, etc.\, to an auto-bi
 dding agent interface. With this information\, the interface bids on behal
 f of the advertiser to a central agency running some mechanism (an allocat
 ion rule and payment rule) to allocate the available ad slot to one of the
  bidders. A natural question is: what choice of mechanism provides the mos
 t efficient allocation in this auto-bidding world? Aggarwal et al. (2019) 
 proved that a second price auction incurs a price of anarchy (PoA) of 2\, 
 even with two bidders (i.e.\, social welfare at the equilibrium bidding po
 licy is at least 1/2 times the optimal social welfare achievable). Later M
 ehta (2022) proved that upon allowing randomized mechanisms\, one could ha
 ve a truthful mechanism with a PoA of approx. 1.896 when restricted to ins
 tances with only two bidders. Moreover\, they proved an impossibility resu
 lt that any randomized truthful mechanism has a PoA >=2 as the # of bidder
 s increases to infinity. So\, one natural question can be\, can one have a
  lower PoA by allowing a non-truthful mechanism?\n\nLiaw et al. (2022) add
 ressed this question and proved that\, even for non-truthful mechanisms wi
 th some assumptions\, PoA >=2 as the # of bidders increases to infinity. T
 hey showed that every deterministic mechanism (truthful and non-truthful) 
 satisfying some assumptions has a PoA >= 2\, even with two bidders\, and t
 he bound is tight for first-price auctions. They also constructed a non-tr
 uthful randomized variant of the first-price auction with PoA=1.8 over ins
 tances with two bidders. Moreover\, they proved that after modifying the s
 ame mechanism's payment rule to be truthful\, PoA increases to 1.9\, provi
 ng that non-truthfulness helps in those instances. As long as time permits
 \, we will go through as many results as possible proven in this paper.\n
URL:https://www.tcs.tifr.res.in/web/events/1282
DTSTART;TZID=Asia/Kolkata:20230324T143000
DTEND;TZID=Asia/Kolkata:20230324T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1283
DTSTAMP:20230914T125957Z
SUMMARY:Introduction in Topological Vector Spaces and Banach Spaces
DESCRIPTION:Speaker: Sourav  Roy\n\nAbstract: \nWe will start basic definit
 ions and examples. We will try to cover Duality in Banach Spaces\, Compact
  operators. If time permits  we will see some convexity results known "Se
 paration Theorem" and "Hahn- Banach Theorem".\n
URL:https://www.tcs.tifr.res.in/web/events/1283
DTSTART;TZID=Asia/Kolkata:20230331T160000
DTEND;TZID=Asia/Kolkata:20230331T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1284
DTSTAMP:20230914T125957Z
SUMMARY:On Robustness for Linear Recurrence Sequences
DESCRIPTION:Speaker: Mihir Vahanwala (MPI-SWS\, Saarbrücken)\n\nAbstract: 
 \nThe Skolem\, Positivity\, and Ultimate Positivity problems for Linear Re
 currence Sequences (LRS) are number-theoretic problems whose decidability 
 has been open for decades. They are known to be at least as hard as Diopha
 ntine approximation\, an open number-theoretic problem. LRS have scientifi
 c applications ranging from theoretical biology to software verification a
 nd formal languages. Given the inherent imprecision and need for safety ma
 rgins in the real world\, we consider the problems for LRS with the follow
 ing notion of robustness: does the sequence satisfy the required property 
 despite small perturbations in the given initialisation? Although some int
 erpretations of this notion yield problems that are still Diophantine hard
 \, others can be shown to be decidable\, in PSPACE even! In this talk\, we
  discuss how the decision procedure strings together remarkable and profou
 nd results from computational algebra\, number theory\, and logic. The tec
 hniques we discuss are indeed a thematic feature of modern progress in thi
 s area\, and we briefly sketch how they have been extended to handle more 
 sophisticated semi-algebraic reachability sets\, and to tackle the problem
  of invariant synthesis.\nBio: Mihir Vahanwala is a doctoral researcher a
 t MPI-SWS\, Saarbrücken. He works in the Foundations of Algorithmic Verif
 ication group led by Joël Ouaknine.\n
URL:https://www.tcs.tifr.res.in/web/events/1284
DTSTART;TZID=Asia/Kolkata:20230405T160000
DTEND;TZID=Asia/Kolkata:20230405T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1285
DTSTAMP:20230914T125957Z
SUMMARY:Minimization of weighted automaton
DESCRIPTION:Speaker: Mohit Upmanyu (TIFR\, Mumbai)\n\nAbstract: \nWe will d
 efine a weighted automaton over a semiring\, give examples and explain how
  to find a minimal weighted automaton (for certain rings like fields\, int
 egers etc.)\,  If time permits we will then discuss how this helps solve 
 the problem of checking whether two weighted automata are equal or not.\n
URL:https://www.tcs.tifr.res.in/web/events/1285
DTSTART;TZID=Asia/Kolkata:20230406T180000
DTEND;TZID=Asia/Kolkata:20230406T190000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1286
DTSTAMP:20230914T125957Z
SUMMARY:Dual Mirror Descent for Online Allocation Problems
DESCRIPTION:Speaker: Agniv Bandyopadhyay\n\nAbstract: \nWe will look at the
  situation where an agent decides what action to take sequentially over a 
 finite time horizon to maximize revenue subject to resource consumption co
 nstraints. Every time the revenue generated will be some concave function 
 of the action picked. Also\, the revenue function and resource consumption
  will be sampled i.i.d. from some fixed distribution every time\, and that
  distribution will be unknown to the agent.  Balseiro\, Hu\, and Mirrokni
  (2020) introduced a general class of algorithms for this problem\, which 
 achieves sublinear regret. The algorithm maintains a dual multiplier at ev
 ery time step and uses online mirror descent to update it.  Depending on 
 the regularizer chosen\, the policy can be equivalent to dual sub-gradient
  descent and dual-multiplicative weight update. Moreover\, this framework 
 can achieve sublinear regret in repeated second-price auctions where\, unl
 ike the online allocation problem\, bidders are unaware of their revenue f
 unctions and resource consumption (payment) before deciding their bid.\n\n
 Our discussion will be based on the contents of the following paper:\n"Dua
 l Mirror Descent for Online Allocation Problems"-Santiago Balseiro\, Haiha
 o Lu\, Vahab Mirrokni\, In: Proceedings of the 37th International Conferen
 ce on Machine Learning\, PMLR 119:613-628\, 2020\n
URL:https://www.tcs.tifr.res.in/web/events/1286
DTSTART;TZID=Asia/Kolkata:20230421T160000
DTEND;TZID=Asia/Kolkata:20230421T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1287
DTSTAMP:20230914T125958Z
SUMMARY:Bounded Negativity and Harbourne constants on Algebraic Surfaces
DESCRIPTION:Speaker: Aditya Subramaniam (TIFR)\n\nAbstract: \nStudy of Alge
 braic Surfaces is a classical subject. To understand surfaces\, it is natu
 ral to study the various properties of the curves on them. Even now\, ther
 e are several interesting conjectures about the properties of curves on su
 rfaces. One such conjecture is the Bounded Negativity Conjecture (BNC).\nL
 et X be a nonsingular projective surface. Bounded Negativity Conjecture (B
 NC) says that there is an integer b(X)\, depending only on X\, such that t
 he self-intersection C^2 is at least b(X) for every reduced curve C on X. 
 This conjecture is false in positive characteristic\, but it is open in ch
 aracteristic zero\, except in trivial cases. Harbourne constants were defi
 ned in an attempt to tackle this problem. I will introduce some of these i
 deas in this talk.\n
URL:https://www.tcs.tifr.res.in/web/events/1287
DTSTART;TZID=Asia/Kolkata:20230428T160000
DTEND;TZID=Asia/Kolkata:20230428T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1288
DTSTAMP:20230914T125958Z
SUMMARY:Foundations of Lattice-based Cryptography
DESCRIPTION:Speaker: Rajendra Kumar (Weizmann institute)\n\nAbstract: \nPub
 lic key cryptography is essential for internet security\, and RSA and Diff
 ie-Hellman are the most widely used public-key cryptosystems for internet 
 traffic. However\, recent progress in building quantum computers threatens
  RSA and Diffie-Hellman's security\, as they are vulnerable to quantum adv
 ersaries. To address this\, organizations like the National Institute of S
 tandards and Technology (NIST) and the European Telecommunications Standar
 ds Institute (ETSI) have started standardizing and deploying cryptosystems
  that are secure against quantum attacks. Recently\,  NIST has chosen Kyb
 er and Dilithium\, lattice-based candidates\, as primary algorithms for se
 curity against quantum adversaries. The security of these cryptosystems cr
 ucially relies on the assumption that the best-known algorithms for the la
 ttice problems cannot be significantly improved.\nIn this talk\, I will di
 scuss the connections between the security of lattice-based cryptosystems 
 and the hardness of lattice problems. I will talk about classical and quan
 tum algorithms for lattice problems. I will also discuss the works on the 
 fine-grained security of lattice-based Crypto.\n
URL:https://www.tcs.tifr.res.in/web/events/1288
DTSTART;TZID=Asia/Kolkata:20230501T110000
DTEND;TZID=Asia/Kolkata:20230501T120000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1289
DTSTAMP:20230914T125958Z
SUMMARY:On Complexity measures of Boolean functions
DESCRIPTION:Speaker: Tulasi mohan Molli\n\nAbstract: \nBoolean functions ca
 pture various problems and situations arising in computer science and othe
 r areas. In this thesis\, we study boolean functions using three complexit
 y measures namely Probabilistic degree\, decision tree depth and Fourier d
 imension. The thesis and the talk are organized into three parts one for e
 ach of these measures.\nIn the first part of the talk\, we will focus on t
 he Probabilistic degree of OR over Reals. This is based on joint work with
  Bhandari\, Harsha and Srinivasan. In this part\, we will look at the cons
 truction of a Probabilistic Polynomial for OR over Reals\, which improves 
 on the previous best construction due to Toda-Ogiwara and Beigel\, Tarui\,
  Reingold and Speilman.  We will also look at a lower bound on the Probab
 ilistic degree of OR which matches our upper bound construction in a restr
 icted setting.\n\nIn the second part\, we will focus on decision trees of 
 Boolean functions after random restrictions.\nThis is based on joint work 
 with Harsha and Shankar. In this part\, we will look at the notion of the 
 criticality of a Boolean function which captures several properties of Boo
 lean functions tightly. In our work\, we prove a switching lemma-like stat
 ement for Boolean Formulas which settles a conjecture of Rossman.\nIn the 
 third part\, we will look at a bunch of complexity measures which arise ou
 t of the Fourier representation of Boolean functions and study the relatio
 nship between them.  This is based on joint work with Chakraborty\, Mande
 \, Mittal\, Paraashar and Sanyal. In this part\, we will focus on a couple
  of upper bounds on the Fourier dimension in terms of Fourier sparsity\, w
 eight\, Fourier max-entropy and  Fourier max-rank entropy. We will also e
 xhibit functions which match these bounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1289
DTSTART;TZID=Asia/Kolkata:20230502T160000
DTEND;TZID=Asia/Kolkata:20230502T180000
LOCATION:Hybrid Mode (A-201)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1290
DTSTAMP:20230914T125958Z
SUMMARY:Towards Next-Generation ML/AI: Robustness\, Optimization\, Privacy
DESCRIPTION:Speaker: Krishna Pillutla (Google Research\, U.S.A.)\n\nAbstrac
 t: \nTwo trends have taken hold in machine learning and artificial intelli
 gence: a move to massive\, general-purpose\, pre-trained models as well as
  a move to small\, on-device models trained on distributed data. Both thes
 e disparate settings face some common challenges: a need for (a) robustnes
 s to deployment conditions that differ from training\, (b) faster optimiza
 tion\, and (c) protection of data privacy.\nAs a result of the former tren
 d\, large language models have displayed emergent capabilities they have n
 ot been trained for. Recent models such as ChatGPT have attained the abili
 ty to generate remarkably human-like long-form text. I will describe Mauve
 \, a measure to quantify this ability by measuring the gap between the dis
 tribution of generated text and that of human-written text. I will highlig
 ht its good empirical performance and present some statistical estimation 
 results.\nThe move to massively distributed on-device federated learning o
 f models opens up new challenges due to the natural diversity of the under
 lying user data and the need to protect its privacy. I will discuss how to
  reframe the learning problem to make the model robust to natural distribu
 tion shifts arising from deployment on diverse users who do not conform to
  the population trends in a manner that admits a distributed optimization 
 algorithm with end-to-end differential privacy.\nTo conclude\, I will disc
 uss my ongoing efforts and future plans to work toward the next generation
  of ML/AI techniques by combining the best of both worlds. I will discuss 
 applications ranging from differentially private language models and text 
 generation to decentralized learning.\n\nBio: Krishna Pillutla is a visiti
 ng researcher (postdoc) at Google Research\, USA in the Federated Learning
  team. He obtained his Ph.D. at the University of Washington where he was 
 advised by Zaid Harchaoui and Sham Kakade. Before that\, he received his M
 .S. from Carnegie Mellon University and B.Tech. from IIT Bombay where he w
 as advised by Nina Balcan and J. Saketha Nath respectively. Krishna's rese
 arch has been recognized by a NeurIPS outstanding paper award (2021) and a
  JP Morgan Ph.D. fellowship (2019-20).\n
URL:https://www.tcs.tifr.res.in/web/events/1290
DTSTART;TZID=Asia/Kolkata:20230502T190000
DTEND;TZID=Asia/Kolkata:20230502T200000
LOCATION:Online
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1291
DTSTAMP:20230914T125958Z
SUMMARY:Towards a Principled Approach to Large Scale Data Analysis
DESCRIPTION:Speaker: Parthe Pandit (University of California\, San Diego)\n
 \nAbstract: \nThe contemporary practice of data analysis is driven in larg
 e part by deep neural networks. These complex models have had a tremendous
  impact on a broad range of applications in science and engineering. Train
 ing deep neural networks however\, remains an art with practitioners relyi
 ng on heuristics and trial-&-error procedures. To make Data Science reliab
 le and widely accessible\, we need to develop a theoretical foundation to 
 characterize the behavior of these complex models\, and come up with simpl
 er substitutes firmly grounded in engineering principles.\nRecently\, a cl
 assical model -- Kernel Methods -- has emerged as a framework to understan
 d the behavior of deep neural networks\, following the discovery of the Ne
 ural Tangent Kernel. This leads to a natural question as to whether Kernel
  Methods can provide a simpler substitute to Deep Neural Networks\, while 
 achieving the same prediction performance and scalability. I will present 
 2 works which show progress in this direction:\n1. Recursive Feature Machi
 nes: a new class of adaptive kernel methods that learn task-specific featu
 res (arxiv.org/2212.13881 [1])\,\n2. EigenPro3: a new iterative algorithm 
 that enables scalable training of large kernel models (arxiv.org/2302.0260
 5 [2])\, accepted at ICML 2023.\n\nBio: Parthe Pandit is a Simons postdoc
 toral fellow with the Halıcıoğlu Data Science Institute at UC San Diego
 . He obtained his Ph.D. in Electrical and Computer Engineering\, and M.S. 
 in Statistics both from UCLA\, and a B.Tech. + M.Tech. dual degree in Elec
 trical Engineering with a minor in Computer Science from IIT Bombay.\nHis 
 research spans Machine Learning and Signal Processing with a focus on the 
 design and statistical analysis of iterative procedures for estimation and
  inference in high dimensions. He has been a recipient of the Jack K. Wolf
  student paper award at ISIT 2019\, and a Distinguished PhD dissertation f
 inalist at UCLA ECE in 2022. He was a research intern with Amazon Search a
 nd Amazon AWS working on Large Language Models\; and with Citadel LLC\, wo
 rking on optimal trade execution in financial markets. Apart from Machine 
 Learning and Signal Processing\, he has also published articles in Graph T
 heory\, Coding Theory\, Network Economics\, and planning EV charging infra
 structure.\n
URL:https://www.tcs.tifr.res.in/web/events/1291
DTSTART;TZID=Asia/Kolkata:20230504T090000
DTEND;TZID=Asia/Kolkata:20230504T100000
LOCATION:Screening in A-201 with Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1292
DTSTAMP:20230914T125958Z
SUMMARY:Simulation Is All You Need
DESCRIPTION:Speaker: Akshit Kumar (Columbia University\, U.S.A.)\n\nAbstrac
 t: \nMotivated by online matching markets and network revenue management (
 NRM) problems with many types (e.g.\, fulfillment optimization)\, we study
  dynamic spatial matching (DSM) in which supply and demand live in d dimen
 sional space and need to be matched with each other dynamically. If demand
  and supply have the same spatial distribution\, greedy matching suffices\
 , and achieves average match distance of the same order as the distance to
  the nearest neighbor. If demand and supply have different spatial distrib
 utions\, the matching constraint has bite and greedy matching fails. We in
 troduce a unifying and practical algorithmic principle for NRM and DSM dub
 bed SOAR: Simulate\, Optimize\, Assign\, Repeat\, which repeatedly simulat
 es the future to enable good matching decisions. Simulating one sample pat
 h at each stage already enables SOAR to produce near optimal regret for th
 e majority of NRM models in the literature\, and for DSM with non-atomic d
 emand and supply distributions. For particularly challenging NRM and DSM m
 odels\, SOAR with multiple simulated sample paths at each stage achieves n
 ear optimal regret. This is joint work with Omar Besbes\, Yilun Chen\, Yas
 h Kanoria and Wenxin Zhang based on two papers linked here and here.\n
URL:https://www.tcs.tifr.res.in/web/events/1292
DTSTART;TZID=Asia/Kolkata:20230511T160000
DTEND;TZID=Asia/Kolkata:20230511T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1293
DTSTAMP:20230914T125958Z
SUMMARY:Why Robust Generalization in Deep Learning is Difficult: Perspectiv
 e of Expressive Power
DESCRIPTION:Speaker: Santanu Das\n\nAbstract: \nIt is commonly known that m
 odern neural networks become sensitive when they get exposed to adversaria
 l examples. To get rid of this problem\, people start to train neural netw
 orks by using adversarial training algorithms and adversarial examples as 
 training data. However\, although the robust training error can be equal t
 o near zero by using some methods\, but the robust generalization error re
 mains high for all those existing adversarial training algorithms. My talk
  will be based on the paper "Why Robust Generalization in Deep Learning is
  Difficult: Perspective of Expressive Power " authored by Binghui Li\, Jik
 ai Jin2\,Han Zhong\, John E. Hopcroft\, Liwei Wang3. In this paper\, the a
 uthors provide a theoretical understanding of this phenomenon from the per
 spective of expressive power for deep neural networks.\n
URL:https://www.tcs.tifr.res.in/web/events/1293
DTSTART;TZID=Asia/Kolkata:20230512T143000
DTEND;TZID=Asia/Kolkata:20230512T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1294
DTSTAMP:20230914T125958Z
SUMMARY:Broadcast Channel Synthesis
DESCRIPTION:Speaker: Malhar Ajit  Managoli\n\nAbstract: \nIn a coordination
  or channel synthesis problem\, parties have to use communication and shar
 ed randomness to produce correlated random outputs. The question is\, how 
 much communication and/or shared randomness is required to accurately gene
 rate correlation.\nIn this project\, we study the problem of three parties
  synthesizing a noisy broadcast channel. The first party observes a random
  variable X\, and sends a common message to the other two\, who have to pr
 oduce random variables Y and Z according to a prescribed distribution.\n
URL:https://www.tcs.tifr.res.in/web/events/1294
DTSTART;TZID=Asia/Kolkata:20230515T170000
DTEND;TZID=Asia/Kolkata:20230515T180000
LOCATION:A238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1295
DTSTAMP:20230921T105046Z
SUMMARY:Some results at the Intersection of Game Theory and Logic
DESCRIPTION:Speaker: Ramit Das (The Institute of Mathematical Sciences (IMS
 c)\, Chennai)\n\nAbstract: \nWe shall address the issues of modelling or f
 ormalising  game theoretic properties like Nash Equilibrium\, Finite Impr
 ovement Property\, Weak Acyclicity of various game forms in various kinds 
 of logic. We shall investigate the _expressive powers_ offered by each log
 ic\, the _model checking_ theorems and also a _completeness_ proof  of a 
 decidable logic variant. We hope that this investigation would  have an i
 mpact on the formalisation of game theory and its allied areas like comput
 ational social choice theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1295
DTSTART;TZID=Asia/Kolkata:20230518T110000
DTEND;TZID=Asia/Kolkata:20230518T120000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1296
DTSTAMP:20230914T125958Z
SUMMARY:Functionality of a Random Graph is Polylogarithmic
DESCRIPTION:Speaker: Pavel Dvorak\n\nAbstract: \nThe functionality of a gra
 ph defined by [Alecu et al.: Graph functionality\, JCTB2021] is a paramete
 r that generalizes graph degeneracy.\nInformally\, the functionality of a 
 graph G is minimal k such that in any induced subgraph H of G there is a v
 ertex v in H and a set S of k vertices that the adjacency of v and any ver
 tex u in H is determined by adjacency of u and S.\nI'll show that random g
 raph G = G(n\,p) has functionality asymptotically at least log n and at mo
 st log^3 n. The upper bound is a fresh new result\, I'll be happy to discu
 ss its correctness.\nThis is joint work with L. Folwarczný\, M. Opler\, P
 . Pudlák\, R. Šámal\, T. Vu.\n
URL:https://www.tcs.tifr.res.in/web/events/1296
DTSTART;TZID=Asia/Kolkata:20230526T160000
DTEND;TZID=Asia/Kolkata:20230526T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1297
DTSTAMP:20230914T125958Z
SUMMARY:New results on reasoning using transformers
DESCRIPTION:Speaker: Piyush Srivastava\n\nAbstract: \nIn the ML reading gro
 up this Friday\, we will look at a circuit model (or "architecture") calle
 d "transformer" that ostensibly underlies recent popular applications such
  as ChatGPT\, Bard and friends.  We\, however\, will focus on works (most
 ly empirical as of now) that attempt to understand its power in the more r
 estricted setting of learning to "reason" in the setting of a restricted p
 roof system.  Two examples we will look at are\n1) Straight Line Programs
 \n2) Proofs in the Isabelle proof system.\nReferences:\nVaswani\, Ashish\,
  Noam Shazeer\, Niki Parmar\, Jakob Uszkoreit\, Llion Jones\, Aidan N Gome
 z\, Łukasz Kaiser\, and Illia Polosukhin. "Attention Is All You Need." In
  Advances in Neural Information Processing Systems\, Vol. 30. Curran Assoc
 iates\, Inc.\, 2017. https://papers.nips.cc/paper/2017/hash/3f5ee243547dee
 91fbd053c1c4a845aa-Abstract.html.\nZhang\, Yi\, Arturs Backurs\, Sébastie
 n Bubeck\, Ronen Eldan\, Suriya Gunasekar\, and Tal Wagner. "Unveiling Tra
 nsformers with LEGO: A Synthetic Reasoning Task." arXiv\, February 17\, 20
 23. http://arxiv.org/abs/2206.04301.\nMikuła\, Maciej\, Szymon Antoniak\,
  Szymon Tworkowski\, Albert Qiaochu Jiang\, Jin Peng Zhou\, Christian Szeg
 edy\, Łukasz Kuciński\, Piotr Miłoś\, and Yuhuai Wu. "Magnushammer: A 
 Transformer-Based Approach to Premise Selection." arXiv\, March 8\, 2023. 
 https://doi.org/10.48550/arXiv.2303.04488.\n
URL:https://www.tcs.tifr.res.in/web/events/1297
DTSTART;TZID=Asia/Kolkata:20230602T143000
DTEND;TZID=Asia/Kolkata:20230602T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1298
DTSTAMP:20230914T125958Z
SUMMARY:The AKS algorithm
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nAKS (Agra
 wal-Kayal-Saxena) algorithm is the first known algorithm for primality tes
 ting that is both provably efficient (not dependent on generalized Riemann
  hypothesis) and deterministic. I shall present the analysis of this algor
 ithm.\n\nPaper: https://annals.math.princeton.edu/2004/160-2/p12\n
URL:https://www.tcs.tifr.res.in/web/events/1298
DTSTART;TZID=Asia/Kolkata:20230602T160000
DTEND;TZID=Asia/Kolkata:20230602T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1299
DTSTAMP:20230914T125958Z
SUMMARY:Lower bounds for Polynomial Calculus with extension variables over 
 finite fields
DESCRIPTION:Speaker: Sasank Mouli (University of California\, San Diego)\n\
 nAbstract: \nPropositional proof complexity aims to prove lower bounds aga
 inst tautological Boolean formulae for increasingly strong proof systems\,
  with the ultimate goal of separating NP and coNP. A major open problem in
  this area is lower bounds for AC0[p]-Frege proofs. Since lower bounds for
  the corresponding circuit class AC0[p] were proved by Razborov and Smolen
 sky through algebraic means\, algebraic proof systems such as Nullstellens
 atz (Beame et. al.) and Polynomial Calculus (Clegg et. al.) were introduce
 d with the intention of better understanding AC0[p]-Frege. Lower bounds fo
 r the former systems have been obtained but it has not led to much progres
 s for the latter. In this talk we will show how to obtain lower bounds for
  a weak version of Polynomial Calculus with extension variables\, a proof 
 system which with strong enough extension variables can simulate AC0[p]-Fr
 ege. In particular we show that for every prime p and n > 0\, there exist 
 tautologies over O(n log n) variables of degree O(log n) such that any Pol
 ynomial Calculus proof with o(n^2) extension variables\, each depending on
  O(log n) original variables requires exponential size. This builds on a r
 ecent work of Sokolov (STOC 2020) and is joint work with Russell Impagliaz
 zo and Toniann Pitassi\, appearing in CCC 2023.\n
URL:https://www.tcs.tifr.res.in/web/events/1299
DTSTART;TZID=Asia/Kolkata:20230605T160000
DTEND;TZID=Asia/Kolkata:20230605T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1300
DTSTAMP:20230914T125958Z
SUMMARY:Inference\, Compression\, and Communication under Limited Data Acce
 ss
DESCRIPTION:Speaker: Sahasranand Kodinthirapully Ramanadhan (Institut Polyt
 echnique de Paris)\n\nAbstract: \nFirst\, we consider a two-party distribu
 ted hypothesis testing problem for correlated Gaussian random variables. F
 or a d-dimensional random vector X and a scalar Y\, where X and Y are join
 tly Gaussian with an unknown correlation vector $\\rho$\, parties $\\mathc
 al{P}_1$ and $\\mathcal{P}_2$ observe independent copies of X and Y\, resp
 ectively. The parties seek to test if their observations are correlated or
  not\, namely they seek to test if $\\|\\rho\\|_2$ exceeds $\\tau$ or is i
 t 0. To that end\, they communicate interactively and declare the test out
 put. We show that roughly order $d/\\tau^2$ bits of communication are suff
 icient and necessary for resolving the distributed correlation testing pro
 blem above. Furthermore\, we establish a lower bound of roughly $d^2/\\tau
 ^2$ bits for the communication needed for distributed estimation of $\\rho
 $\, implying that distributed correlation testing requires less communicat
 ion than distributed estimation. Towards the end\, we shall discuss briefl
 y a streaming signal compression problem where access to samples is limite
 d\, and another recent work wherein we provide partial resolution to a 27-
 year-old conjecture regarding the capacity of queue channels by considerin
 g a limited form of feedback.\nBio: Sahasranand is currently a postdoctora
 l fellow at Telecom Paris. He has completed his PhD from ECE\, IISc in 202
 2. His research interests include statistical inference\, information theo
 ry\, and signal processing.\n
URL:https://www.tcs.tifr.res.in/web/events/1300
DTSTART;TZID=Asia/Kolkata:20230606T163000
DTEND;TZID=Asia/Kolkata:20230606T173000
LOCATION:Online
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1301
DTSTAMP:20230914T125958Z
SUMMARY:Stochastic Approximations of Sampling Algorithms
DESCRIPTION:Speaker: Dheeraj Nagaraj (Google AI\, Bangalore)\n\nAbstract: \
 nWe consider stochastic approximations of sampling algorithms like Langevi
 n Monte Carlo (pathwise approximation via random batches) and Stein Variat
 ional Gradient Descent (approximation in the space of distributions). Thes
 e algorithms are heavily deployed in Bayesian inference\, and the physical
  sciences.\nWe first consider pathwise approximation in Stochastic Gradien
 t Langevin Dynamics (SGLD)\, we show that the noise induced by the random 
 batches is approximately Gaussian (due to the Central Limit Theorem) while
  the Brownian motion driving the algorithm is exactly Gaussian.  We utili
 ze this structure to provide improved guarantees for sampling algorithms u
 nder significantly weaker assumptions. We then propose covariance correcti
 on\, which rescales the brownian motion to approximately remove the random
  batch error. We show that covariance corrected algorithms enjoy even bett
 er convergence.\nWe then consider stochastic approximation in the space of
  probability distributions to obtain a new particle discretization of Stei
 n Variational Gradient Descent (SVGD)\, an interacting particle based samp
 ling algorithm. We introduce and analyze Virtual Particle SVGD (VP-SVGD)\,
  which enjoys provably rapid convergence to the target. Our rates provide 
 a double exponential improvement over the prior state of the art convergen
 ce results for SVGD under mild conditions\, giving us the first provably f
 ast variant of SVGD.\nBased on joint work with Aniket Das (Google) and Ana
 nt Raj (INRIA and UIUC)\n
URL:https://www.tcs.tifr.res.in/web/events/1301
DTSTART;TZID=Asia/Kolkata:20230608T110000
DTEND;TZID=Asia/Kolkata:20230608T120000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1302
DTSTAMP:20230914T125958Z
SUMMARY:Randomness Requirements for Three-Secret Sharing
DESCRIPTION:Speaker: Hari Krishnan P A\n\nAbstract: \nConsider a secret sha
 ring problem with three secrets related to each other\, i.e.\, we allow on
 ly certain combinations of the three secrets. A dealer produces three shar
 es such that every pair of share reveals a certain secret and nothing abou
 t the other two secrets other than what can be inferred from the revealed 
 secret. We bound the randomness complexity of each possible set of permiss
 ible combinations and give randomness-optimal schemes for the same for bin
 ary secrets.\nThis is a joint work with Aayush Rajesh\, Varun Narayanan\, 
 Manoj Prabhakaran and Vinod Prabhakaran.\n
URL:https://www.tcs.tifr.res.in/web/events/1302
DTSTART;TZID=Asia/Kolkata:20230609T140000
DTEND;TZID=Asia/Kolkata:20230609T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1303
DTSTAMP:20230914T125958Z
SUMMARY:Differentiable Algorithms for Representation\, Processing and Rende
 ring of Shapes
DESCRIPTION:Speaker: Aalok Gangopadhyay (IIT Gandhinagar)\n\nAbstract: \nOn
 e of the primary objectives of visual computing has been the development o
 f representations and algorithms that enable computer systems to acquire\,
  process\, and render shapes efficiently. While numerous representations a
 nd algorithms have been proposed\, many involve non-differentiable compone
 nts\, making them incompatible with gradient-based optimization methods. T
 he first part of this talk centers around developing differentiable repres
 entations and rendering techniques for shapes. We present our work on desi
 gning differentiable parameterized families of homeomorphisms and diffeomo
 rphisms\, possibly with additional symmetry constraints\, which are used t
 o deform a template shape having desired topological properties. This enab
 les us to address shape search problems using gradient-based optimization 
 methods. We showcase our results for various applications\, including sear
 ching for curve embeddings whose perspective projections resemble a target
  image\, untangling knots\, parametrization of prototiles belonging to spe
 cific isohedral tiling classes\, and density estimation on identification 
 spaces. In the subsequent part of this talk\, we focus on learning-based f
 rameworks\, which generate differentiable algorithms for shape-processing 
 problems. Specifically\, we will elaborate on our work on surface denoisin
 g\, surface correspondence\, temporal surface blending\, and curve extract
 ion problems. The talk concludes with a discussion on future directions an
 d potential areas of exploration for advancing the field.\n
URL:https://www.tcs.tifr.res.in/web/events/1303
DTSTART;TZID=Asia/Kolkata:20230612T160000
DTEND;TZID=Asia/Kolkata:20230612T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1304
DTSTAMP:20230921T105046Z
SUMMARY:DANSE - Data-driven Non-linear State Estimation in Unsupervised Lea
 rning
DESCRIPTION:Speaker: Saikat Chatterjee (KTH Royal Institute of Technology\,
  Stockholm\, Sweden)\n\nAbstract: \nWe address the tasks of Bayesian state
  estimation and forecasting for a model-free process in an unsupervised le
 arning setup. In the seminar\, we discuss our new method called DANSE -- D
 ata-driven Nonlinear State Estimation method. DANSE provides a closed-form
  posterior of the state of the model-free process\, given linear measureme
 nts of the state. In addition it provides a closed-form posterior for fore
 casting. We show how data-driven recurrent neural networks (RNNs) are used
  in the DANSE to provide closed-form prior of the state and posterior. The
  training of DANSE\, mainly learning the parameters of RNN\, is executed i
 n unsupervised learning approach. In the unsupervised learning\, we have a
 ccess to a training dataset comprising of only a set of measurement data t
 rajectories\, but we do not have any access to the state trajectories. The
 refore\, DANSE does not have access to state information in training data 
 and can not use supervised learning. Using simulated linear and non-linear
  process models (Lorenz attractor and Chen attractor)\, we evaluate the un
 supervised learning-based DANSE. We show that the proposed DANSE\, without
  knowledge of the process model and without supervised learning\, provides
  a competitive performance against model-driven methods\, such as Kalman f
 ilter (KF)\, extended KF (EKF) and unscented KF (UKF)\, and a recently pro
 posed hybrid method called KalmanNet.\n
URL:https://www.tcs.tifr.res.in/web/events/1304
DTSTART;TZID=Asia/Kolkata:20230616T160000
DTEND;TZID=Asia/Kolkata:20230616T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1305
DTSTAMP:20230914T125958Z
SUMMARY:Communication with Byzantine Users
DESCRIPTION:Speaker: Neha Sangwan\n\nAbstract: \nDistributed systems are ub
 iquitous in modern society. These systems consist of a collection of nodes
  or computers connected through a network. One of the fundamental requirem
 ents of any distributed system is fault tolerance – even if some nodes a
 re faulty or hacked\, it should not affect the functioning of the system a
 s a whole.  In this talk\, we will focus on two aspects of fault toleranc
 e:\n(1) Is it possible to design a mechanism which allows different nodes 
 to reach consensus\, for example\, on a common state of the system or data
 \, even in the presence of faulty nodes?\n(2) Can multiple nodes send info
 rmation reliably over a shared communication medium\, even when some nodes
  do not follow the protocol?\nTo answer the first question\, we focus on r
 ealizing a cryptographic primitive called the byzantine broadcast\, which 
 ensures consensus among honest nodes in a network with one sender and mult
 iple receivers. We use stochastic resources (like correlated randomness or
  a noisy channel) to realize this primitive. For the second question\, we 
 model the setting using a noisy channel with multiple senders and a single
  receiver (also called a multiple access channel) where some of the sender
 s may maliciously deviate from the protocol. We study communication in thi
 s model while ensuring that malicious senders are not able to cause undete
 cted decoding errors for the honest senders.\n
URL:https://www.tcs.tifr.res.in/web/events/1305
DTSTART;TZID=Asia/Kolkata:20230621T113000
DTEND;TZID=Asia/Kolkata:20230621T130000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1306
DTSTAMP:20230914T125958Z
SUMMARY:Game of arrivals at a two queue network with heterogeneous route ch
 oice
DESCRIPTION:Speaker: Agniv Bandyopadhyay\n\nAbstract: \nConsiderable resear
 ch has focused on modelling customer arrival time to queues as games where
  customers are strategic and non-cooperative in selecting their arrivals a
 nd their costs are a function of the queueing delays as well as service co
 mpletion times. Customers are typically modelled as fluid or non-atomic pa
 rticles and services are assumed to have a deterministic rate. Most applic
 ations involving strategic customers who think about when to join a queuin
 g system fit this setting including customers arriving at a service provid
 er(s)\, traffic networks and so on. Most of the literature has focused on 
 a single queue. Some works consider tandem and more general queuing networ
 ks where customers have homogeneous routes. This homogeneity leads to subs
 tantial analytical simplification. However\, there are many practical sett
 ings where more than one queue is involved and customers have different ro
 utes. Motivated by this\, we consider a queuing network that opens at a sp
 ecified time\, where customers are non-atomic and belong to different clas
 ses. Each class has its own route\, and as is typical in the literature\, 
 the costs are a linear function of waiting and service completion time. We
  restrict ourselves to a two class\, two queue network: this simplificatio
 n is well motivated as the diversity in solution structure as a function o
 f problem parameters is substantial even in this simple setting (e.g.\, a 
 specific routing structure involves eight different regions)\, suggesting 
 a combinatorial blow up as the number of queues\, routes and customer clas
 ses increase. We identify the unique Nash equilibrium customer arrival pro
 file when the customer linear cost preferences are different. When custome
 r cost preferences match\, under certain parametric settings\, the equilib
 rium arrival profiles may not be unique and may lie in a convex set. We fu
 rther make a surprising observation that in some parametric settings\, cus
 tomers in one class may arrive in disjoint intervals\, although the union 
 of the arrival times across the two classes is always an interval. Further
 \, the two classes may arrive in contiguous intervals or in overlapping in
 tervals\, and at varying rates within an interval\, depending upon the pro
 blem parameters. In this talk\, we will cover the existing works on single
  queue setting and tandem networks. Following that\, if time permits\, we 
 will go through the analysis of the two queue settings.\nThis talk will be
  based on joint work with Sandeep Juneja.\n
URL:https://www.tcs.tifr.res.in/web/events/1306
DTSTART;TZID=Asia/Kolkata:20230623T160000
DTEND;TZID=Asia/Kolkata:20230623T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1307
DTSTAMP:20230914T125958Z
SUMMARY:Counting Markov equivalence directed cyclic graphs consistent with 
 background knowledge
DESCRIPTION:Speaker: Vidya Sagar Sharma\n\nAbstract: \nWe study the problem
  of counting the number of directed acyclic graphs in a Markov equivalence
  class (MEC) that are consistent with background knowledge specified in t
 he form of the directions of some additional edges in the MEC.  A polynom
 ial-time algorithm for the special case of the problem\, when no backgroun
 d knowledge constraints are specified\, was given by Wienöbst\, Bannach\,
  and Liśkiewicz (AAAI 2021)\, who also showed that the general case is NP
 -hard (in fact\, \\#P-hard).  In this talk\, we show that the problem is 
 nevertheless tractable in an interesting class of instances\, by establish
 ing that it is ``fixed-parameter tractable'' (FPT): we give an algorithm t
 hat runs in time $O(k! k^2 n^4)$\, where $n$ is the number of nodes in the
  MEC and $k$ is the maximum number of nodes in any maximal clique of the M
 EC that participate in the specified background knowledge constraints.  I
 n particular\, our algorithm runs in polynomial time in the well-studied s
 pecial case of MECs of bounded tree-width or bounded maximum clique size.
 \nPaper link: https://arxiv.org/abs/2206.06744\n
URL:https://www.tcs.tifr.res.in/web/events/1307
DTSTART;TZID=Asia/Kolkata:20230626T170000
DTEND;TZID=Asia/Kolkata:20230626T180000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1308
DTSTAMP:20230914T125958Z
SUMMARY:Tree-like Resolution and Decision Trees
DESCRIPTION:Speaker: Farzan Byramji (IIT Kanpur\, UCSD)\n\nAbstract: \nIt i
 s well-known that tree-like resolution refutations correspond to decision 
 trees solving the associated false clause search problem. We describe this
  connection and some lower bounds using this. Then we discuss variants of 
 tree-like resolution (resolution with parities and AND-resolution) along w
 ith the corresponding decision tree models\, and lifting in this setting.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1308
DTSTART;TZID=Asia/Kolkata:20230629T160000
DTEND;TZID=Asia/Kolkata:20230629T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1309
DTSTAMP:20230914T125958Z
SUMMARY:New results on reasoning using transformer\, Part 2
DESCRIPTION:Speaker: Piyush Srivastava\n\nAbstract: \nIn the ML reading gro
 up this Friday\, we will look at a circuit model (or "architecture") calle
 d "transformer" that ostensibly underlies recent popular applications such
  as ChatGPT\, Bard and friends.  We\, however\, will focus on works (mostl
 y empirical as of now) that attempt to understand its power in the more re
 stricted setting of learning to "reason" in the setting of a restricted pr
 oof system.  Two examples we will look at are\n\n1) Straight Line Programs
 \n2) Proofs in the Isabelle proof system.\n\nReferences:\n Vaswani\, Ashis
 h\, Noam Shazeer\, Niki Parmar\, Jakob Uszkoreit\, Llion Jones\, Aidan N G
 omez\, Łukasz Kaiser\, and Illia Polosukhin. "Attention Is All You Need."
  In Advances in Neural Information Processing Systems\, Vol. 30. Curran As
 sociates\, Inc.\, 2017. https://papers.nips.cc/paper/2017/hash/3f5ee243547
 dee91fbd053c1c4a845aa-Abstract.html.\n Zhang\, Yi\, Arturs Backurs\, Séba
 stien Bubeck\, Ronen Eldan\, Suriya Gunasekar\, and Tal Wagner. "Unveiling
  Transformers with LEGO: A Synthetic Reasoning Task." arXiv\, February 17\
 , 2023. http://arxiv.org/abs/2206.04301.\nMikuła\, Maciej\, Szymon Antoni
 ak\, Szymon Tworkowski\, Albert Qiaochu Jiang\, Jin Peng Zhou\, Christian 
 Szegedy\, Łukasz Kuciński\, Piotr Miłoś\, and Yuhuai Wu. "Magnushammer
 : A Transformer-Based Approach to Premise Selection." arXiv\, March 8\, 20
 23. https://doi.org/10.48550/arXiv.2303.04488.\n
URL:https://www.tcs.tifr.res.in/web/events/1309
DTSTART;TZID=Asia/Kolkata:20230630T143000
DTEND;TZID=Asia/Kolkata:20230630T153000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1310
DTSTAMP:20230914T125958Z
SUMMARY:Optimal social choice functions: A utilitarian view
DESCRIPTION:Speaker: Soumyajit Pyne\n\nAbstract: \nThe authors adopt a util
 itarian perspective on social choice\, assuming that agents have (possibly
  latent) utility functions over some space of alternatives. For many reaso
 ns one might consider mechanisms\, or social choice functions\, that only 
 have access to the ordinal rankings of alternatives by the individual agen
 ts rather than their utility functions. In this context\, one possible obj
 ective for a social choice function is the maximization of (expected) soci
 al welfare relative to the information contained in these rankings. In the
  talk\, we will focus on the worst case model (distortion) of the paper.\n
 The link of the paper: https://www.sciencedirect.com/science/article/pii/S
 0004370215000892\n
URL:https://www.tcs.tifr.res.in/web/events/1310
DTSTART;TZID=Asia/Kolkata:20230707T160000
DTEND;TZID=Asia/Kolkata:20230707T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1311
DTSTAMP:20230914T125958Z
SUMMARY:The unreasonable effectiveness of mathematics in large scale deep l
 earning
DESCRIPTION:Speaker: Greg Yang (Microsoft New England Research and Developm
 ent Center\, USA)\n\nAbstract: \nRecently\, the theory of infinite-width n
 eural networks led to the first technology\, muTransfer\, for tuning enorm
 ous neural networks that are too expensive to train more than once. For ex
 ample\, this allowed us to tune the 6.7 billion parameter version of GPT-3
  using only 7% of its pretraining compute budget\, and with some asterisks
 \, we get a performance comparable to the original GPT-3 model with twice 
 the parameter count. In this talk\, I will explain the core insight behind
  this theory. In fact\, this is an instance of what I call the Optimal Sca
 ling Thesis\, which connects infinite-size limits for general notions of "
 size" to the optimal design of large models in practice. I'll end with sev
 eral concrete key mathematical research questions whose resolutions will h
 ave an incredible impact on the future of AI.\n
URL:https://www.tcs.tifr.res.in/web/events/1311
DTSTART;TZID=Asia/Kolkata:20230712T110000
DTEND;TZID=Asia/Kolkata:20230712T123000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1312
DTSTAMP:20230914T125958Z
SUMMARY:A Sanov-type theorem for unimodular marked random graphs and its ap
 plications
DESCRIPTION:Speaker: Sarath Yasodharan (Brown University\, U.S.A.)\n\nAbstr
 act: \nWe prove a Sanov-type large deviation principle for the component e
 mpirical measures of certain sequences of unimodular random graphs (includ
 ing Erdos-Renyi and random regular graphs) whose vertices are marked with 
 i.i.d. random variables. Specifically\, we show that the rate function can
  be expressed in a fairly tractable form involving suitable relative entro
 py functionals. As a corollary\, we establish a variational formula for th
 e annealed pressure (or limiting log partition function) for various stati
 stical physics models on sparse random graphs.\nJoint work with I-Hsun Che
 n and Kavita Ramanan.\n
URL:https://www.tcs.tifr.res.in/web/events/1312
DTSTART;TZID=Asia/Kolkata:20230712T160000
DTEND;TZID=Asia/Kolkata:20230712T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1313
DTSTAMP:20230914T125959Z
SUMMARY:Strategic Decision-Making for Information Freshness
DESCRIPTION:Speaker: Kumar Saurav\n\nAbstract: \nClassical network scheduli
 ng problems have primarily focused on optimizing metrics\, such as delay\,
  which pertain to the service provided to individual packets in the networ
 k. However\, in modern applications like tele-robotics and networked cars\
 , the emphasis is on metrics that capture the freshness of information\, s
 pecifically\, how up-to-date the information is at the receiver (monitor) 
 compared to the transmitter (source). Thus\, several metrics have been int
 roduced to quantify information freshness\, the most widely used one being
  the age of information (AoI). The AoI for a source at any given time is e
 qual to the difference between the current time and the generation time of
  the most recent packet (update) received at the monitor.  For modern app
 lications\, the scheduling objective is to minimize the AoI for the source
 s in an online environment\, where only causal information is available at
  any time.\nA critical feature of AoI scheduling problems is that not all 
 updates generated at a source need to be transmitted. Depending on the net
 work model\, a scheduling algorithm (policy) must choose a subset of updat
 es to transmit. This characteristic gives AoI scheduling problems a combin
 atorial flavour\, making them fundamentally different and analytically cha
 llenging compared to classical scheduling problems. In the PhD dissertatio
 n\, we have addressed some major challenges in AoI scheduling for generic 
 network models\, taking into consideration energy consumption\, shared tra
 nsmission link\, and the type of scheduler (centralized/decentralized). We
  have analyzed the various trade-offs involved in decision-making and prop
 osed novel causal algorithms (policies) that strategically handle these tr
 ade-offs. Additionally\, using analytical techniques\, we have derived the
 oretical performance guarantees\, ensuring the efficiency and robustness o
 f the proposed solutions. In this seminar\, we will have a comprehensive o
 verview of the above contributions\, with all the relevant background.\n
URL:https://www.tcs.tifr.res.in/web/events/1313
DTSTART;TZID=Asia/Kolkata:20230713T160000
DTEND;TZID=Asia/Kolkata:20230713T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1314
DTSTAMP:20230914T125959Z
SUMMARY:Majority-3SAT in Polynomial Time
DESCRIPTION:Speaker: Ratnakar Medepalli\n\nAbstract: \nMajority-SAT is the 
 problem of determining whether a boolean formula evaluates to true on more
  than half of its assignments. Majority-SAT is known to be PP-hard. In thi
 s talk\, we will see a polynomial time algorithm for Majority-3SAT\, which
  is the problem of determining whether a 3-CNF formula evaluates to true o
 n more than half of its assignments. The result is surprising because most
  SAT-related problems remain hard when restricted to their corresponding 3
 -CNF variant.\nThis is a result of Shyan Akmal and Ryan Williams from FOCS
  2021.\n
URL:https://www.tcs.tifr.res.in/web/events/1314
DTSTART;TZID=Asia/Kolkata:20230714T140000
DTEND;TZID=Asia/Kolkata:20230714T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1315
DTSTAMP:20230914T125959Z
SUMMARY:Robust Mean Estimation of Gaussian Random Variables
DESCRIPTION:Speaker: Malhar Ajit  Managoli\n\nAbstract: \nSuppose we are gi
 ven a set of n i.i.d. samples from a Gaussian with known variance but unkn
 own mean. We wish to estimate the mean. It is well known that the sample m
 ean is an excellent estimator for the true mean.\nHowever\, if a small fra
 ction of the samples are corrupted (i.e. chosen by an adversary instead of
  being drawn from the Gaussian)\, the sample mean can fail spectacularly.\
 nIn this talk\, I will present an estimator which is robust to such corrup
 tions and also show a lower bound.\n
URL:https://www.tcs.tifr.res.in/web/events/1315
DTSTART;TZID=Asia/Kolkata:20230714T160000
DTEND;TZID=Asia/Kolkata:20230714T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1316
DTSTAMP:20230914T125959Z
SUMMARY:Strong bounds for three-term progressions
DESCRIPTION:Speaker: Raghu Meka (University of California\, Los Angeles)\n\
 nAbstract: \nSuppose you have a set $S$ of integers from $\\{1\,2\,...\,N\
 \}$ that contains at least $N / C$ elements. Does such a set contain three
  equally spaced numbers (i.e.\, a 3-term arithmetic progression)? For exam
 ple\, the set $S$  from $\\{1\,2\,...\, 40\\}$ comprised of the following
  15 numbers $\\{1\,2\,4\,5\,10\,11\,13\,14\,28\,29\,31\,32\,37\,38\,40\\}$
  avoids every 3-term arithmetic progression.\nWhat is the largest value of
  $C$ such that for large enough $N$\, every such set $S$ necessarily conta
 ins a 3-term arithmetic progression?\nIn 1953\, Roth showed this is the ca
 se when $C$ is roughly (log log N). Behrend in 1946 showed that $C$ can be
  at most $exp(\\sqrt(\\log N))$. Since then\, the problem has been a corne
 rstone of the area of additive combinatorics. Following a series of remark
 able results\, a celebrated paper from 2020 due to Bloom and Sisask improv
 ed the lower bound on $C$ to $C = (\\log N)^{1+c}$ for some constant $c > 
 0$.\nThis talk will describe a new work showing that $C$ can be as big as 
 $exp((log N)^{0.08})$\, thus getting closer to Behrend's construction. Bas
 ed on joint work with Zander Kelley (Univ of Illinois\, Urbana Champaign).
 \n
URL:https://www.tcs.tifr.res.in/web/events/1316
DTSTART;TZID=Asia/Kolkata:20230719T160000
DTEND;TZID=Asia/Kolkata:20230719T170000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1317
DTSTAMP:20230914T125959Z
SUMMARY:Strong bounds for three-term progressions (Part II)
DESCRIPTION:Speaker: Raghu Meka (University of California\, Los Angeles)\n\
 nAbstract: \nSuppose you have a set $S$ of integers from $\\{1\,2\,...\,N\
 \}$ that contains at least $N / C$ elements. Does such a set contain three
  equally spaced numbers (i.e.\, a 3-term arithmetic progression)? For exam
 ple\, the set $S$  from $\\{1\,2\,...\, 40\\}$ comprised of the following
  15 numbers $\\{1\,2\,4\,5\,10\,11\,13\,14\,28\,29\,31\,32\,37\,38\,40\\}$
  avoids every 3-term arithmetic progression.\nWhat is the largest value of
  $C$ such that for large enough $N$\, every such set $S$ necessarily conta
 ins a 3-term arithmetic progression?\nIn 1953\, Roth showed this is the ca
 se when $C$ is roughly (log log N). Behrend in 1946 showed that $C$ can be
  at most $exp(\\sqrt(\\log N))$. Since then\, the problem has been a corne
 rstone of the area of additive combinatorics. Following a series of remark
 able results\, a celebrated paper from 2020 due to Bloom and Sisask improv
 ed the lower bound on $C$ to $C = (\\log N)^{1+c}$ for some constant $c > 
 0$.\nThis talk will describe a new work showing that $C$ can be as big as 
 $exp((log N)^{0.08})$\, thus getting closer to Behrend's construction. Bas
 ed on joint work with Zander Kelley (Univ of Illinois\, Urbana Champaign).
 \n
URL:https://www.tcs.tifr.res.in/web/events/1317
DTSTART;TZID=Asia/Kolkata:20230721T110000
DTEND;TZID=Asia/Kolkata:20230721T120000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1318
DTSTAMP:20230914T125959Z
SUMMARY:A Formal Approach to Exchange Design and Regulation
DESCRIPTION:Speaker: Suneel Sarswat\n\nAbstract: \nExchanges such as that o
 f foreign currency\, stocks\, and commodities are organized marketplaces w
 here trades are conducted by matching buy and sell requests of traders. Se
 veral instances have been reported where exchanges have been found violati
 ng regulatory guidelines and the stated rules. In this work\, we propose a
  robust approach to exchange design and regulation by presenting a compreh
 ensive framework for formalizing and certifying double auctions\, which ar
 e the key mechanisms employed by the exchanges to match the buy and sell r
 equests of traders. Typically\, two types of double auctions are employed 
 in the exchanges: call auctions and continuous auctions. For call auctions
  again\, there are two main alternatives:  uniform price and dynamic pric
 e. Our main contributions are as follows.\n-- Call auctions: We formalize 
 the various notions of call auctions and provide fully formalized algorith
 ms for uniform and dynamic price auctions along with their correctness pro
 ofs.\n-- Continuous auctions: We formulate the specifications for continuo
 us double auctions by identifying three simple and necessary properties an
 d formally proving that they are in fact sufficient\; they completely dete
 rmine the input-output relationship. We then formally verify that a natura
 l algorithm satisfies these properties.\n-- Uniqueness theorems: We establ
 ish new uniqueness theorems for both call and continuous auctions that ena
 ble us to build automated checkers that are guaranteed to detect errors in
  the trade logs of exchanges if they generate transactions that violate th
 e specifications. We extract verified programs of our formalized algorithm
 s to build automated checkers.\n-- Tests on real data: We add preprocessin
 g steps that enable us to tailor our general model to a specific exchange.
  We then run our automated checkers on real data. Furthermore\, we report 
 the running times on various input sizes.\n-- Efficiency: We obtain tight 
 bounds on the time complexity of all these three matching problems in the 
 comparison model. Specifically\, we demonstrate that uniform price matchin
 g can be achieved in linear time\, which is an improvement over the previo
 us algorithm that takes O(n log n) time to match n requests. For dynamic p
 rice matching\, we establish a lower bound of Ω(n log n) on the running t
 ime\, thereby proving that the currently known best algorithm is time-effi
 cient. Furthermore\, for continuous double auctions\, we show that a natur
 al algorithm takes O(n log n) time\, while any algorithm requires at least
  Ω(n log n) time.\n
URL:https://www.tcs.tifr.res.in/web/events/1318
DTSTART;TZID=Asia/Kolkata:20230721T140000
DTEND;TZID=Asia/Kolkata:20230721T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1319
DTSTAMP:20230914T125959Z
SUMMARY:Fast Algorithms for Regression Problems
DESCRIPTION:Speaker: Deeksha Adil (ETH Zurich\, Switzerland)\n\nAbstract: \
 nIncreasing data sizes necessitate fast and efficient algorithms for analy
 zing them. Regression is one such essential tool that is used widely in co
 mputer science. In this talk\, I will focus on the "p-norm regression prob
 lem"\, which is a generalization of the standard "linear regression proble
 m"\, and captures several important problems including the maximum flow pr
 oblem on graphs. Historically\, obtaining fast\, high-accuracy algorithms 
 for this problem has been challenging due to the lack of smoothness and st
 rong convexity of the function\, however\, recent breakthroughs have been 
 able to get around these issues. I will present an overview of how these a
 lgorithms work and discuss some generalizations of these techniques to oth
 er regression problems.\n
URL:https://www.tcs.tifr.res.in/web/events/1319
DTSTART;TZID=Asia/Kolkata:20230724T160000
DTEND;TZID=Asia/Kolkata:20230724T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1320
DTSTAMP:20230914T125959Z
SUMMARY:Sampling Algorithms via random walks on polytopes
DESCRIPTION:Speaker: Sourav  Roy\n\nAbstract: \nGiven a polytope K of R^n\,
  the problem of sampling from the uniform distribution over K arises in va
 rious contexts. Till now there are various types of random walks proposed 
 on K. In this talk we will talk about Dikin Walk\, Vaidya Walk\, John Walk
  defined on K.\n
URL:https://www.tcs.tifr.res.in/web/events/1320
DTSTART;TZID=Asia/Kolkata:20230728T160000
DTEND;TZID=Asia/Kolkata:20230728T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1321
DTSTAMP:20230921T105046Z
SUMMARY:A small numerical study about violation of additivity of Holevo cap
 acity for sending classical information through quantum channels
DESCRIPTION:Speaker: Sai Praveen\n\nAbstract: \nWe provide numerical eviden
 ce that appropriately defined random quantum channels violate additivity o
 f Holevo capacity for sending classical information by at least 2^{-182} b
 its. The channel achieving this violation acts on a 366 qubit input and gi
 ves a 187 qubit output.\n
URL:https://www.tcs.tifr.res.in/web/events/1321
DTSTART;TZID=Asia/Kolkata:20230731T111500
DTEND;TZID=Asia/Kolkata:20230731T121500
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1322
DTSTAMP:20230914T125959Z
SUMMARY:Quantum error correction using Generalized surface codes
DESCRIPTION:Speaker: Pavithran Iyer (Xanadu Quantum Technologies\, Canada)\
 n\nAbstract: \nA large-scale quantum computer is envisioned to leverage th
 e theoretical guarantees of the fault-tolerant accuracy threshold theorem 
 to ensure that long computations be carried out reliably\, even in the pre
 sence of noise. Quantum Error Correction (QEC) is an integral part of an F
 T protocol specifying noise-resilient quantum information storage. Quantum
  error-correcting codes encode information in entangled states of many phy
 sical qubits. Topological stabilizer codes are a  widely studied class of
  quantum error-correcting codes wherein the physical qubits are associated
  with a tessellation of a surface. The geometric locality of physical qubi
 ts in topological codes has both advantages and drawbacks. On the positive
  side\, it simplifies the engineering challenges of implementing them on c
 ertain hardware platforms. However\, it imposes a strict limitation on the
  scaling of the fraction of logical qubits that can be encoded per physica
 l qubit. In general\, it is useful to know several parameters of a surface
  code to deem its usefulness.\nIn this presentation\, I will introduce a g
 eneralized formalism for the study of a specific subclass of topological c
 odes called surface codes. Based on findings from [1]\, I will demonstrate
  an efficient method to compute the number of logical qubits and the dista
 nce of a generalized surface code. Additionally\, I will discuss results f
 rom [2]\, showing how to effectively benchmark the performance of generali
 zed surface codes under the error model described by quantum erasures. Las
 tly\, I will present a tool from [3] that facilitates the analysis of gene
 ralized surface codes.\nRelated works:\n[1]: Generalized surface codes and
  packing of logical qubits. Nicolas Delfosse\, Pavithran Iyer\, David Poul
 in. https://arxiv.org/abs/1606.07116\n[2]: A linear-time benchmarking tool
  for generalized surface codes. Nicolas Delfosse\, Pavithran Iyer\, David 
 Poulin.\nhttps://arxiv.org/abs/1611.04256.\n[3]: SQUAB: A Fast Benchmarkin
 g Software for Surface Quantum Computing\nArchitectures. http://quantum-sq
 uab.com [1].\n
URL:https://www.tcs.tifr.res.in/web/events/1322
DTSTART;TZID=Asia/Kolkata:20230801T160000
DTEND;TZID=Asia/Kolkata:20230801T170000
LOCATION:in person @ R.No. AG-69 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1323
DTSTAMP:20230914T125959Z
SUMMARY:Combinatorial Nullstellensatz
DESCRIPTION:Speaker: Rohan Goyal (Chennai Mathematical Institute)\n\nAbstra
 ct: \nWe will see a proof of Combinatorial Nullstellensatz and a few of it
 s applications.\n
URL:https://www.tcs.tifr.res.in/web/events/1323
DTSTART;TZID=Asia/Kolkata:20230802T160000
DTEND;TZID=Asia/Kolkata:20230802T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1324
DTSTAMP:20230914T125959Z
SUMMARY:STCS Annual Symposium 2023
DESCRIPTION:Speaker: \n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1324
DTSTART;TZID=Asia/Kolkata:20230803T093000
DTEND;TZID=Asia/Kolkata:20230804T183000
LOCATION:AG 69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1325
DTSTAMP:20230914T125959Z
SUMMARY:A sublinear time algorithm for approximately perfect matchings in r
 egular graphs
DESCRIPTION:Speaker: Varsha Dani (Golisano College of Computing and Informa
 tion Sciences\, Rochester Institute of Technology\, U.S.A.)\n\nAbstract: \
 nA breakthrough sequence of papers by Goel\, Kapralov\, and Khanna gave t
 he first sublinear-time algorithms for finding large matchings in regular
  bipartite graphs. The crown jewel of these is an $O(n \\log n)$ algorith
 m to find a perfect matching\, based on the idea of randomly generated au
 gmenting paths.\nWe discuss the extent to which the restrictions of being 
 regular and bipartite can be relaxed.  In particular\, we will show that\
 , for all d-regular (non-bipartite) graphs\, a matching using a (1-1/(d+1)
 ) fraction of the vertices can be found in O(n log d) time. At the heart o
 f our algorithm is a new method for turning walks that alternate between m
 atching and non-matching edges into alternating paths.\n
URL:https://www.tcs.tifr.res.in/web/events/1325
DTSTART;TZID=Asia/Kolkata:20230808T160000
DTEND;TZID=Asia/Kolkata:20230808T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1326
DTSTAMP:20230914T125959Z
SUMMARY:Dynamic Pricing and Matching for Online Marketplaces
DESCRIPTION:Speaker: Sushil Varma (Georgia Tech\, Georgia)\n\nAbstract: \nM
 otivated by applications from the gig economy and online marketplaces\, we
  study a bipartite matching network under joint pricing and matching contr
 ols. The objective is to maximize the long-run average profit and minimize
  the delay for the system. In the first part of the talk\, we propose a tw
 o-price policy and max-weight matching policy and show that it exhibits a 
 η1/3 optimality rate when all the arrival rates are scaled by η. We also
  demonstrate the advantage of max-weight matching with respect to the numb
 er of server and customer types by proving and exploiting state space coll
 apse. In the second part of the talk\, we consider the special case of sin
 gle customer and server type. The focus is on obtaining the entire distrib
 ution of the queue length in heavy traffic. A key observation is that\, un
 like a classical queue\, the limiting distribution of a matching queue exh
 ibits a phase transition. These results are established by generalizing th
 e characteristic function method.\n
URL:https://www.tcs.tifr.res.in/web/events/1326
DTSTART;TZID=Asia/Kolkata:20230810T160000
DTEND;TZID=Asia/Kolkata:20230810T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1327
DTSTAMP:20230914T125959Z
SUMMARY:Some musings on hypercontractivity
DESCRIPTION:Speaker: Eeshan Modak\n\nAbstract: \nHypercontractivity is one 
 of those interesting ideas that has been discovered/studied independently 
 by different communities. We will first look at the general definition of 
 hypercontractivity and two different perspectives of it: one from the info
 rmation theory community and the other from the computer science community
 . We'll then look at its generalization\, i.e.  the Brascamp-Lieb inequal
 ity and some of its alternate formulations.\nThis talk is loosely based on
  Chandra Nair's tutorial https://www.youtube.com/watch?v=oL1YvAEF450\n
URL:https://www.tcs.tifr.res.in/web/events/1327
DTSTART;TZID=Asia/Kolkata:20230811T160000
DTEND;TZID=Asia/Kolkata:20230811T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1328
DTSTAMP:20230914T125959Z
SUMMARY:Monotone Depth Lower Bounds using Communication Complexity
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya\n\nAbstract: \nWe shall 
 show that any monotone circuit (with fan-in 2) which determines if a graph
  has a perfect matching must have depth $\\Omega(n)$. This shows that effi
 cient deterministic parallel algorithms for the perfect matching problem m
 ust use negation. To do so\, we shall use tools from communication complex
 ity: more specifically\, we shall show that such a circuit will imply a lo
 w-cost communication protocol for set-disjointness\, which is known to be 
 hard.\n
URL:https://www.tcs.tifr.res.in/web/events/1328
DTSTART;TZID=Asia/Kolkata:20230825T160000
DTEND;TZID=Asia/Kolkata:20230825T170000
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1329
DTSTAMP:20230914T125959Z
SUMMARY:Sparsity bounds for factors of sparse polynomials
DESCRIPTION:Speaker: Varun Ramanathan\n\nAbstract: \nThe sparsity of a poly
 nomial is defined as the number of monomials in it. We will show that give
 n a sparse polynomial f with bounded individual degree\, the sparsity of i
 ts factors can be quasi-polynomially bounded by the sparsity of f. This re
 sult is from the paper "Deterministic Factorization of Sparse Polynomials 
 with Bounded Individual Degree" by Bhargava\, Saraf and Volkovich. The pro
 of is beautiful and uses techniques from convex geometry.\n
URL:https://www.tcs.tifr.res.in/web/events/1329
DTSTART;TZID=Asia/Kolkata:20230901T160000
DTEND;TZID=Asia/Kolkata:20230901T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1330
DTSTAMP:20230914T125959Z
SUMMARY:Toward Large Kernel Models
DESCRIPTION:Speaker: Parthe Pandit (University of California\, San Diego)\n
 \nAbstract: \nRecent studies indicate that kernel machines can often perfo
 rm similarly or better than deep neural networks (DNNs) on small datasets.
  The interest in kernel machines has been additionally bolstered by the di
 scovery of their equivalence to wide neural networks in certain regimes. H
 owever\, a key feature of DNNs is their ability to scale the model size an
 d training data size independently\, whereas in traditional kernel machine
 s model size is tied to data size. Because of this coupling\, scaling kern
 el machines to large data has been computationally challenging. In this pa
 per\, we provide a way forward for constructing large-scale general kernel
  models\, which are a generalization of kernel machines that decouples the
  model and data\, allowing training on large datasets. Specifically\, we i
 ntroduce EigenPro 3.0\, an algorithm based on projected dual preconditione
 d SGD and show scaling to model and data sizes which have not been possibl
 e with existing kernel methods.\nParthe is a Simons postdoctoral fellow wi
 th the Halıcıoğlu Data Science Institute at UCSD. He obtained his Ph.D.
  in ECE from UCLA\, and his undergrad degree in EE from IIT Bombay. He has
  been a recipient of the Jack K. Wolf student paper award at ISIT 2019.\n
URL:https://www.tcs.tifr.res.in/web/events/1330
DTSTART;TZID=Asia/Kolkata:20230905T160000
DTEND;TZID=Asia/Kolkata:20230905T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1331
DTSTAMP:20230921T105046Z
SUMMARY:Courcelle's theorem
DESCRIPTION:Speaker: Pranshu Gaba\n\nAbstract: \nGiven a graph\, we are oft
 en interested in deciding if it satisfies a certain property. Some example
 s of graph properties include connectivity\, bipartiteness\, and planarity
 . Courcelle's theorem gives parameterized upper bounds for decidability fo
 r a wide class of graph properties. Specifically\, Courcelle's theorem is 
 a metatheorem that states that if a graph property is definable in monadic
  second-order logic on graphs\, then the property is decidable in linear f
 ixed-parameter tractable time with the graph treewidth as the parameter. T
 his theorem finds many uses in automata theory and model checking. We will
  study the theorem and look at some of its applications.\n
URL:https://www.tcs.tifr.res.in/web/events/1331
DTSTART;TZID=Asia/Kolkata:20230908T160000
DTEND;TZID=Asia/Kolkata:20230908T170000
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1332
DTSTAMP:20230914T125959Z
SUMMARY:A Parameterized View on P-matchings
DESCRIPTION:Speaker: Juhi Chaudhary (Ben-Gurion University of the Negev\, I
 srael)\n\nAbstract: \nA matching M is a P-matching if the subgraph induced
  by the endpoints of the edges of M satisfies property P. For example\, if
  the property P is that of being a graph\, being a matching\, being acycli
 c\, or being disconnected\, then we obtain the usual matching\, an induced
  matching\, an acyclic matching\, and a disconnected matching\, respective
 ly. First\, I will survey the latest developments related to P-matchings f
 rom the viewpoint of Parameterized Complexity. Then\, I will describe some
  results focusing majorly on acyclic matchings and on three algorithmic pa
 radigms: approximation hardness\, kernelization lower bounds\, and FPT alg
 orithms with respect to various parameters such as treewidth and some belo
 w-guarantee parameters. The second part of the talk is based on the two re
 cent joint works with Meirav Zehavi\, which appeared in WG’2023.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1332
DTSTART;TZID=Asia/Kolkata:20230912T160000
DTEND;TZID=Asia/Kolkata:20230912T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1333
DTSTAMP:20230920T113426Z
SUMMARY:Quantum Pseudoentanglement
DESCRIPTION:Speaker: Soumik Ghosh (University of Chicago)\n\nAbstract: \nEn
 tanglement is a quantum resource\, in some ways analogous to randomness in
  classical computation. Inspired by recent work of Gheorghiu and Hoban\, w
 e define the notion of "pseudoentanglement''\, a property exhibited by ens
 embles of efficiently constructible quantum states which are indistinguish
 able from quantum states with maximal entanglement. Our construction relie
 s on the notion of quantum pseudorandom states -- first defined by Ji\, Li
 u and Song -- which are efficiently constructible states indistinguishable
  from (maximally entangled) Haar-random states. Specifically\, we give a c
 onstruction of pseudoentangled states with entanglement entropy arbitraril
 y close to logn across every cut\, a tight bound providing an exponential 
 separation between computational vs information theoretic quantum pseudora
 ndomness. We discuss applications of this result to Matrix Product State t
 esting\, entanglement distillation\, and the complexity of the AdS/CFT cor
 respondence.\n
URL:https://www.tcs.tifr.res.in/web/events/1333
DTSTART;TZID=Asia/Kolkata:20230920T100000
DTEND;TZID=Asia/Kolkata:20230920T110000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1336
DTSTAMP:20230921T031459Z
SUMMARY: Conditional Disclosure of Secrets via Non-Linear Reconstruction
DESCRIPTION:Speaker: Ratnakar Medepalli (TIFR)\n\nAbstract: \nConditional D
 isclosure of Secrets (CDS) is the problem in which a set of (non-interacti
 ng) parties reveal a secret to a receiver if and only if a predicate is tr
 ue. We will see results from the Crypto 2017 paper by Liu\, Vaikuntanathan
  and Wee in which they demonstrated a connection between CDS schemes and a
  class of PIR (Private Information Retrieval) schemes and in the process\,
  described the first CDS scheme with sub-exponential communication complex
 ity.\n
URL:https://www.tcs.tifr.res.in/web/events/1336
DTSTART;TZID=Asia/Kolkata:20230922T160000
DTEND;TZID=Asia/Kolkata:20230922T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1339
DTSTAMP:20230929T033658Z
SUMMARY:Construction of explicit lossless bipartite expanders
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nA 
 $D\,\\epsilon$ lossless bipartite vertex expander is a $D$-left-regular bi
 partite graph such that for each subset $S$ of the left vertices which is 
 not too large\, the neighborhood of $S$ has size at least $(1-\\epsilon)|S
 |$. Lossless expanders are important because of their usage in constructio
 n of linear time decodable error correcting codes (Sipser-Spielman codes).
  In this talk\, we shall describe the first explicit construction of lossl
 ess expanders by Capalbo\, Wigderson et al.\n
URL:https://www.tcs.tifr.res.in/web/events/1339
DTSTART;TZID=Asia/Kolkata:20230929T160000
DTEND;TZID=Asia/Kolkata:20230929T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1338
DTSTAMP:20230927T111049Z
SUMMARY:A Polynomial time Algorithm for the Minimum Generating set Problem 
 for Groups
DESCRIPTION:Speaker: Dhara Thakkar (IIT Gandhinagar)\n\nAbstract: \nFor a f
 inite group G of order n\, a generating set of minimum size is called a mi
 nimum generating set of G. A Cayley table for G is a representation of a g
 roup to an algorithm. It stores the product of the ith and jth element for
  each i\,j ∈ {1\,2\,..\,n}.\nGiven a group G of order n\, by its Cayley 
 table\, output the size of a minimum generating set problem is known as th
 e minimum generating set (MIN-GEN) problem. The MIN-GEN problem admits a t
 rivial algorithm that runs in time n^{\\log n+O(1)}. In this talk\, I will
  present a polynomial time algorithm that solves the MIN-GEN problem. Our 
 algorithm also finds one minimum generating set for a given group.\nFinite
  groups can also be represented by their generating set as input. Let G \\
 leq S_m be a primitive permutation group given by its generating set. We o
 btain a quasi-polynomial (in m) time algorithm that outputs the size of a 
 minimum generating set when G is a primitive permutation group.\nThis talk
  is based on the joint work with Bireswar Das\, and Andrea Lucchini.\n
URL:https://www.tcs.tifr.res.in/web/events/1338
DTSTART;TZID=Asia/Kolkata:20231003T160000
DTEND;TZID=Asia/Kolkata:20231003T173000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1341
DTSTAMP:20231005T090319Z
SUMMARY:Is it associative?
DESCRIPTION:Speaker: Shanthanu  Suresh Rai (TIFR)\n\nAbstract: \nIs a given
  binary operation * on a finite set X associative? We will see a O(n^2) ti
 me randomized algorithm for solving this problem (here n = |X|). If time p
 ermits\, we will also see how the above algorithm can be extended for chec
 king general "read-once" identities.\nReferences:- Jiri Matousek\, Thirty-
 three Miniatures: Mathematical and Algorithmic Applications of Linear Alge
 bra\, American Mathematical Society\, 2010- Rajagopalan\, Sridhar\; Schulm
 an\, Leonard J. (2000). "Verification of Identities". SIAM Journal on Comp
 uting. 29 (4): 1155–1163\n
URL:https://www.tcs.tifr.res.in/web/events/1341
DTSTART;TZID=Asia/Kolkata:20231006T154500
DTEND;TZID=Asia/Kolkata:20231006T171500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1342
DTSTAMP:20231012T044505Z
SUMMARY:Inspiring Trust in Outsourced Computations: From Verifiable Chip Fa
 brication to Secure Deep Learning in the Cloud
DESCRIPTION:Speaker: Siddharth Garg (NYU Tandon)\n\nAbstract: \nComputation
 s are often outsourced by computationally weak clients to computationally 
 powerful external entities. Cloud computing is an obvious example of outso
 urced computation\; outsourced chip manufacturing to off-shore foundries o
 r ``fabs" is another (perhaps less obvious) example.  Indeed\, many major
  semiconductor design companies have now adopted the so-called "fabless" m
 odel. However\, outsourcing raises a fundamental question of trust: how ca
 n the client ascertain that the outsourced computations were correctly per
 formed? First\, we describe the design of "verifiable ASICs" to address th
 e problem of secure chip fabrication at off-shore foundries. Leveraging in
 teractive proof (IP) protocols\, we enable untrusted chips to provide run-
 time proofs of the correctness of computations they perform. These proofs 
 are checked by a slower verifier chip fabricated at a trusted foundry. The
  proposed approach is the first to defend against arbitrary Trojan misbeha
 viors (Trojans refer to malicious modifications of a chip's blueprint by t
 he foundry) while providing formal and comprehensive soundness guarantees.
 \nNext\, we examine the "MLaaS" setting\, in which both the training and/o
 r inference of machine learning models is outsourced to the cloud. MLaaS i
 ntroduces both integrity and privacy and integrity risks. ML models can be
  maliciously trained\, or provide incorrect outputs during inference. We d
 escribe tailored IP protocols for a special class of deep networks that us
 e only polynomial activation functions. Finally\, MLaaS also introduces pr
 ivacy risk for users since they share their sensitive data with untrusted 
 cloud applications. Privacy-preserving crypto. methods provide a way out\,
  but are exorbitantly expensive. We show how deep network architectures ca
 n be tailored to reduce crypto costs by up to two orders of magnitude.\n
URL:https://www.tcs.tifr.res.in/web/events/1342
DTSTART;TZID=Asia/Kolkata:20231013T110000
DTEND;TZID=Asia/Kolkata:20231013T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1337
DTSTAMP:20230925T045659Z
SUMMARY:Harnessing Multiple BMC Engines Together for Efficient Formal Verif
 ication
DESCRIPTION:Speaker: Ansuman Banerjee (Indian Statistical Institute\, Kolka
 ta)\n\nAbstract: \nIn recent times\, Bounded Model Checking (BMC) engines 
 are gaining wide prominence and showing great effectiveness in formal veri
 fication. Today\, an arsenal of different BMC engines exist\, differing wi
 dely in the optimization\, representations and solving mechanisms used to 
 represent and navigate the underlying state transition system as they look
  for property violations. When having a concrete verification task at hand
 \, a designer is often confronted with the problem of engine selection\, a
 nd more often than not\, has to resort to manually designed selection heur
 istics or machine-learned strategies using carefully selected features of 
 the design. It has often been observed that these different engines have d
 ifferent strengths and weaknesses\, depending on the nature of the verific
 ation task\, the property and the complexity of the design. This talk will
  present a recent work that was set off to examine if combinations of thes
 e engines can help to combine the strengths. We talk about a recent work f
 rom our group that proposes an approach to create a sequencing of BMC engi
 nes that can reach better depths in formal verification\, as opposed to ex
 ecuting them alone. Our approach uses machine learning\, specifically\, th
 e Multi-Armed Bandit paradigm of Reinforcement Learning\, to predict the b
 est-performing BMC engine for a given unrolling depth of the underlying de
 sign transition system. We present an evaluation of our approach to show t
 hat our proposed approach outperforms state-of-the-art BMC engines in term
 s of the depth reached or time taken to deduce a property violation on the
  Hardware Model Checking Competition (HWMCC) benchmarks.\n
URL:https://www.tcs.tifr.res.in/web/events/1337
DTSTART;TZID=Asia/Kolkata:20231017T160000
DTEND;TZID=Asia/Kolkata:20231017T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1345
DTSTAMP:20231016T052415Z
SUMMARY:Topology of Omics Data
DESCRIPTION:Speaker: Laxmi Parida (IBM\, NYU Tandon)\n\nAbstract: \nMany pr
 oblems in omics are combinatorial in nature\, i.e.\, the interrelationship
  amongst the entities is at par\, if not more important\, than the value o
 f the entity themselves. Graphs are the most commonly used mathematical ob
 ject to model such relationships. However\, often it is important to captu
 re higher order relationships as well. Topological data analysis provides 
 a natural basis to model such interactions and the use of Logic enables ex
 traction of signal patterns as logical expressions (or hypothesis) from no
 isy data. I will discuss a few applications of such models.\n
URL:https://www.tcs.tifr.res.in/web/events/1345
DTSTART;TZID=Asia/Kolkata:20231020T160000
DTEND;TZID=Asia/Kolkata:20231020T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1346
DTSTAMP:20231020T044050Z
SUMMARY:Counting Markov equivalence classes with the same skeleton
DESCRIPTION:Speaker: Vidya Sagar Sharma (TIFR)\n\nAbstract: \nWe study a di
 rected acyclic graphical model\, also known as a Bayesian network. In this
  model\, a directed acyclic graph (DAG) is used to represent conditional d
 ependence between random variables. Two DAGs are said to be Markov equival
 ent if both represent the same set of conditional independence between the
  random variables. Verma and Pearl (1990) show that two DAGs are Markov eq
 uivalent if\, and only if\, both have the same skeleton (underlying undire
 cted graph) and the same v-structures (induced subgraph of the form $a\\ri
 ghtarrow b \\leftarrow c$). Markov equivalent DAGs belong to the same Mark
 ov equivalent class (MEC). A graphical representation of an MEC is the uni
 on of the DAGs it contains.An interesting problem related to the study of 
 MECs is: for an input undirected graph $G$\, count the MECs with skeleton 
 $G$. This problem has both graphical and statistical significance. In this
  talk\, we will discuss a polynomial algorithm that solves the problem whe
 n the skeleton is a tree graph. We will also explore a fixed parameter tra
 ctable algorithm to solve the problem.\n
URL:https://www.tcs.tifr.res.in/web/events/1346
DTSTART;TZID=Asia/Kolkata:20231020T180000
DTEND;TZID=Asia/Kolkata:20231020T190000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1349
DTSTAMP:20231025T111829Z
SUMMARY:Counting Markov equivalence classes with the same skeleton
DESCRIPTION:Speaker: Vidya Sagar Sharma (TIFR)\n\nAbstract: \nWe study a di
 rected acyclic graphical model\, also known as a Bayesian network. In this
  model\, a directed acyclic graph (DAG) is used to represent conditional d
 ependence between random variables. Two DAGs are said to be Markov equival
 ent if both represent the same set of conditional independence between the
  random variables. Verma and Pearl (1990) show that two DAGs are Markov eq
 uivalent if\, and only if\, both have the same skeleton (underlying undire
 cted graph) and the same v-structures (induced subgraph of the form $a\\ri
 ghtarrow b \\leftarrow c$). Markov equivalent DAGs belong to the same Mark
 ov equivalent class (MEC). A graphical representation of an MEC is the uni
 on of the DAGs it contains.An interesting problem related to the study of 
 MECs is: for an input undirected graph $G$\, count the MECs with skeleton 
 $G$. This problem has both graphical and statistical significance. This is
  a continuation of last week's talk. In last week's talk\, we discussed a 
 polynomial time algorithm that solves the problem when the skeleton is a t
 ree graph. In this talk\, we will explore a fixed parameter tractable algo
 rithm to solve the problem. We will recall the necessary prerequisites fro
 m the previous talk.\n
URL:https://www.tcs.tifr.res.in/web/events/1349
DTSTART;TZID=Asia/Kolkata:20231027T170000
DTEND;TZID=Asia/Kolkata:20231027T183000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1351
DTSTAMP:20231031T013539Z
SUMMARY:Statistically Near-Optimal Hypothesis Selection
DESCRIPTION:Speaker: Klim Efremenko (Ben-Gurion University of the Negev)\n\
 nAbstract: \nHypothesis Selection is a fundamental distribution learning 
 problem where given a comparator-class Q={q_1\,...\, q_n} of distribution
 s and a sampling access to an unknown target distribution p\, the goal is 
 to output a distribution q such that tv(p\,q) is close to \\opt\, where $\
 \text{opt} = \\min_i\\{\\text{tv}(p\,q_i)\\}$ and $\\text{tv}(\\cdot\, \\c
 dot)$ denotes the total-variation distance. Despite the fact that this pro
 blem has been studied since the 19th century\, its complexity in terms of 
 basic resources\, such as a number of samples and approximation guarantees
 \, remains unsettled. This is in stark contrast with other (younger) learn
 ing settings\, such as PAC learning\, for which these complexities are wel
 l understood.\nWe derive an optimal 2-approximation learning strategy for
  the Hypothesis Selection problem with a (nearly) optimal sample complexit
 y of~$\\tilde O(\\log n/\\epsilon^2)$. This is the first algorithm that si
 multaneously achieves the best approximation factor and sample complexity:
  previously\, Bousquet\, Kane\, and Moran ({\\it COLT `19}) gave a learner
  achieving the optimal $2$-approximation\, but with an exponentially worse
  sample complexity of $\\tilde O(\\sqrt{n}/\\epsilon^{2.5})$\, and Yatraco
 s~({\\it Annals of Statistics `85}) gave a learner with optimal sample com
 plexity of $O(\\log n /\\epsilon^2)$ but with a sub-optimal approximation 
 factor of $3$.\n
URL:https://www.tcs.tifr.res.in/web/events/1351
DTSTART;TZID=Asia/Kolkata:20231031T160000
DTEND;TZID=Asia/Kolkata:20231031T173000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1350
DTSTAMP:20231027T065509Z
SUMMARY:SGD from the Lens of Markov process: An Algorithmic Stability Persp
 ective
DESCRIPTION:Speaker: Anant Raj (University of Illinois at Urbana-Champaign)
 \n\nAbstract: \nIn this talk\, we delve into the intricate relationships b
 etween heavy-tailed distributions\, generalization error\, and algorithmic
  stability in the realm of noisy stochastic gradient descent. Recent resea
 rch has illustrated the emergence of heavy tails in stochastic optimizatio
 n and their intriguing links to generalization error. However\, these stud
 ies often relied on challenging topological and statistical assumptions. E
 mpirical evidence has further challenged existing theory\, suggesting that
  the relationship between heavy tails and generalization is not always mon
 otonic. In response\, we introduce novel insights\, exploring the relation
 ship between tail behavior and generalization properties through the lens 
 of algorithmic stability. Our analysis reveals that the stability of stoch
 astic gradient descent (SGD) varies based on how we measure it\, leading t
 o interesting conclusions about its behavior.Expanding upon these findings
 \, we extend the scope to a broader class of objective functions\, includi
 ng non-convex ones. Leveraging Wasserstein stability bounds for heavy-tail
 ed stochastic processes\, our research sheds light on the non-monotonic co
 nnection between generalization error and heavy tails\, offering a more co
 mprehensive perspective.Additionally\, we introduce a unified approach for
  proving Wasserstein stability bounds in stochastic optimization\, emphasi
 zing time-uniform stability and its role in various scenarios\, including 
 convex and non-convex losses. Our approach is versatile and applicable to 
 popular optimizers\, highlighting the importance of ergodicity.\n
URL:https://www.tcs.tifr.res.in/web/events/1350
DTSTART;TZID=Asia/Kolkata:20231101T203000
DTEND;TZID=Asia/Kolkata:20231101T220000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1354
DTSTAMP:20231103T054543Z
SUMMARY:The Optimal Approximation Factor in the Hypothesis Selection Proble
 m
DESCRIPTION:Speaker: Eeshan Modak (TIFR)\n\nAbstract: \nConsider the follow
 ing problem: Given a collection of probability distributions (q_1\,...\,q_
 n) and a sample access to an unknown target distribution p\, find which q_
 i is closest to p in total variation. Turns out that this problem in gener
 al is not tractable. However\, we can output a q_i such that TV(q_i\,p) <=
  \\beta OPT + \\epsilon. Here OPT is the TV between p and best candidate i
 n our collection.\nIn this talk\, we will see that the approximation facto
 r \\beta has to be at least 3.PS: If you attended Klim Efrimenko's talk th
 en he cited this result but did not go into the proof.\n
URL:https://www.tcs.tifr.res.in/web/events/1354
DTSTART;TZID=Asia/Kolkata:20231103T160000
DTEND;TZID=Asia/Kolkata:20231103T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1340
DTSTAMP:20231031T062211Z
SUMMARY:Black-Box Identity Testing of Noncommutative Rational Formulas in D
 eterministic Quasipolynomial Time
DESCRIPTION:Speaker: Abhranil Chatterjee (Indian Statistical Institute\, Ko
 lkata)\n\nAbstract: \nRational Identity Testing (RIT) is the decision prob
 lem of determining whether or not a given noncommutative rational formula 
 computes zero in the free skew field. It admits a deterministic polynomial
 -time white-box algorithm [Garg et al.\, 2016\; Ivanyos et al.\, 2018\; Ha
 mada and Hirai\, 2021]\, and a randomized polynomial-time black-box algori
 thm [Derksen and Makam\, 2017] via singularity testing of linear matrices 
 over the free skew field.Designing a subexponential-time deterministic RIT
  algorithm in black-box is a major open problem in this area. Despite bein
 g open for several years\, this question has seen very limited progress. I
 n fact\, the only known result in this direction is the construction of a 
 quasipolynomial-size hitting set for rational formulas of only inversion h
 eight two [Arvind et al.\, 2022].In this talk\, I'll present my recent wor
 k where we significantly improve the black-box complexity of this problem
  and obtain the first quasipolynomial-size hitting set for all rational fo
 rmulas of polynomial size. Our construction also yields a quasi-NC RIT al
 gorithm in the white-box setting.\n \nJoint work with V. Arvind (IMSc) an
 d Partha Mukhopadhyay (CMI).\n
URL:https://www.tcs.tifr.res.in/web/events/1340
DTSTART;TZID=Asia/Kolkata:20231107T160000
DTEND;TZID=Asia/Kolkata:20231107T173000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1356
DTSTAMP:20231109T100844Z
SUMMARY:Constructive Proofs of Concentration Bounds
DESCRIPTION:Speaker: Ashutosh Singh (TIFR)\n\nAbstract: \nWe will see a com
 binatorial proof of the Chernoff-Hoeffding bound\, which says that the sum
  of independent {0\,1}-valued random variables is highly concentrated arou
 nd the expected value. We will also see proof for the case of [0\,1]-value
 d random variables. This is based upon the work of Russell Impagliazzo\, V
 alentine Kabanets\, Wolfgang Mulzer\, and Natalia Shenkman.\n
URL:https://www.tcs.tifr.res.in/web/events/1356
DTSTART;TZID=Asia/Kolkata:20231110T160000
DTEND;TZID=Asia/Kolkata:20231110T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1343
DTSTAMP:20231109T045017Z
SUMMARY:Improved constructions of large-dimensional corner-free sets
DESCRIPTION:Speaker: Suhail Sherif (LASIGE\, University of Lisbon)\n\nAbstr
 act: \nIn this talk we will discuss some famous open problems in additive 
 combinatorics:- How large can a subset S of [N] be while managing to avoid
  k-term arithmetic progressions?- How large can a subset S of [N]^k be whi
 le managing to avoid a k-dimensional corner? (If ⋯ represents a 3-term a
 rithmetic progression\, then ⠓ represents a 2-dimensional corner. A more
  formal definition will be provided in the talk\, or can be found in the p
 aper linked below.)We will also discuss multiparty communication complexit
 y\, wherein players are given inputs and they want to compute a function o
 f those inputs. In the Number-In-Hand model\, each player can see their ow
 n input but not the inputs of others. In the Number-On-Forehead model\, ea
 ch player can see the other players' inputs but not their own.In 2021 Lini
 al and Shraibman utilized a long-known connection which showed that findin
 g good k-party Number-On-Forehead communication protocols for the "Exactly
 N" function is equivalent to finding large (k-1)-dimensional-corner-free s
 ets. Working in the setting when k=3\, they constructed an explicit protoc
 ol that matched a 1946 construction of large corner-free sets. Using the c
 ommunication complexity point of view\, they improved upon the protocol to
  create even larger sets\, giving the first improvement to the "highest-or
 der" term since 1946. This was then subsequently improved by Green later t
 hat year.In our work we generalize this method to larger dimensions. We cr
 eate explicit communication protocols that match a 1961 construction of la
 rge k-dimensional-corner-free sets. We then provide an improvement in the 
 same vein as Linial and Shraibman and Green\, giving the first improvement
  to the "highest-order" term since 1961.This is joint work with Lianna Ham
 bardzumyan\, Toniann Pitassi\, Morgan Shirley and Adi Shraibman. The paper
  can be found at https://arxiv.org/abs/2309.06554.\n
URL:https://www.tcs.tifr.res.in/web/events/1343
DTSTART;TZID=Asia/Kolkata:20231114T160000
DTEND;TZID=Asia/Kolkata:20231114T173000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1353
DTSTAMP:20231103T060410Z
SUMMARY:Communication with Byzantine Users
DESCRIPTION:Speaker: Neha Sangwan (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1353
DTSTART;TZID=Asia/Kolkata:20231116T150000
DTEND;TZID=Asia/Kolkata:20231116T160000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1357
DTSTAMP:20231116T105051Z
SUMMARY:The power of regular and permutation branching programs
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \nBranching prog
 rams are computational models which are similar to finite automata. They a
 re particularly interesting because popular pseudorandom generators can fo
 ol certain classes of branching programs. In this talk\, we will see a few
  restricted classes of branching programs\, i.e.\, regular and permutation
  branching programs\, and how effective they are in simulating other branc
 hing programs. All the results are taken from here: https://eccc.weizmann
 .ac.il/report/2023/102/\n
URL:https://www.tcs.tifr.res.in/web/events/1357
DTSTART;TZID=Asia/Kolkata:20231117T160000
DTEND;TZID=Asia/Kolkata:20231117T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1334
DTSTAMP:20231031T050325Z
SUMMARY:Load Balancing under Data Locality: Extending Mean-Field Framework 
 to Constrained Large-Scale Systems
DESCRIPTION:Speaker: Debankur Mukherjee (Georgia Institute of Technology\, 
 Georgia)\n\nAbstract: \nLarge-scale parallel-processing infrastructures su
 ch as data centers and cloud networks form the cornerstone of the modern d
 igital environment. Central to their efficiency are resource management po
 licies\, especially load balancing algorithms (LBAs)\, which are crucial f
 or meeting stringent delay requirements of tasks. A contemporary challenge
  in designing LBAs for today's data centers is navigating data locality co
 nstraints that dictate which tasks are assigned to which servers. These co
 nstraints can be naturally modeled as a bipartite graph between servers an
 d various task types. Most LBA heuristics lean on the mean-field approxima
 tion's accuracy. However\, the non-exchangeability among servers induced b
 y the data locality invalidates this mean-field framework\, causing real-w
 orld system behaviors to significantly diverge from theoretical prediction
 s. From a foundational standpoint\, advancing our understanding in this do
 main demands the study of stochastic processes on large graphs\, thus need
 ing fundamental advancements in classical analytical tools.\nIn this prese
 ntation\, we will delve into recent advancements made in extending the acc
 uracy of mean-field approximation for a broad class of graphs. In particul
 ar\, we will talk about how to design resource-efficient\, asymptotically 
 optimal data locality constraints and how the system behavior changes fund
 amentally\, depending on whether the above bipartite graph is an expander\
 , a spatial graph\, or is inhomogeneous in nature.\n
URL:https://www.tcs.tifr.res.in/web/events/1334
DTSTART;TZID=Asia/Kolkata:20231121T160000
DTEND;TZID=Asia/Kolkata:20231121T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1355
DTSTAMP:20231109T095402Z
SUMMARY:Fourier Growth of Communication Protocols for XOR Functions
DESCRIPTION:Speaker: Makrand Sinha (University of Illinois Urbana-Champaign
 )\n\nAbstract: \nThe Fourier growth of a function refers to the growth of 
 the sum of absolute values of the level-k Fourier coefficients. Bounds on
  the Fourier growth\, even for the first few levels\, have important appli
 cations in pseudorandomness and quantum-versus-classical separations. Tigh
 t bounds on the Fourier growth have been studied for many classes of funct
 ions\, including decision trees and parity decision trees.\n \nWe study t
 he Fourier growth of functions associated to communication protocols for X
 OR functions (functions evaluated on the point-wise XOR of Alice's and Bob
 's inputs). If a protocol C computes an XOR function\, then C(x\,y) is a f
 unction of x + y. This motivates us to study the XOR-fiber of the communic
 ation protocol C\, defined as h(z) := E[C(x\,y)|x + y = z]. These function
 s form a powerful class which includes decision trees and parity decision 
 trees. Proving tight bounds on the Fourier growth of XOR fibers also has a
 pplications to the Gap-Hamming problem and improved quantum versus classic
 al separations in communication complexity.\n \nIn this talk\, we present
  improved Fourier growth bounds for the XOR-fibers of randomized protocols
  that communicate d bits. For the first level\, we show a tight O(sqrt{d})
  bound. For the second level\, we show an improved O(d^{3/2}) bound. We co
 njecture that the optimal bound is O(d.polylog(n)) and leave this as an op
 en question.\n \nOur proof relies on viewing the protocol and its Fourier
  spectrum as a martingale. One crucial ingredient we use to control the st
 ep sizes is a spectral notion of k-wise independence. Loosely speaking\, t
 his corresponds to sets such that the k-th moments of the uniform distribu
 tion on the set are well-behaved in all directions. We show how imposing s
 pectral k-wise independence on Alice's and Bob's sets allows us to prove b
 ounds on the level-k Fourier growth of XOR-fibers. We also provide a way o
 f adaptively partitioning a large set into a few spectrally k-wise indepen
 dent sets.\n \nJoint work with Uma Girish (Princeton University)\, Avisha
 y Tal (UC Berkeley) and Kewen Wu (UC Berkeley).\n
URL:https://www.tcs.tifr.res.in/web/events/1355
DTSTART;TZID=Asia/Kolkata:20231122T143000
DTEND;TZID=Asia/Kolkata:20231122T153000
LOCATION:A-269 (DAA Seminar)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1344
DTSTAMP:20231030T132223Z
SUMMARY:Distinct Elements in Streams: An algorithm for the (text) book
DESCRIPTION:Speaker: Kuldeep S. Meel (University of Toronto)\n\nAbstract: \
 nGiven a data stream of m elements\, the Distinct Elements problem is to e
 stimate the number of distinct elements in the stream. Distinct Elements h
 as been a subject of theoretical and empirical investigations over the pas
 t four decades resulting in space-optimal algorithms for it. However\, all
  the current state-of-the-art algorithms are often difficult to analyze or
  impractical.I will present a simple\, intuitive\, sampling-based space-ef
 ficient algorithm whose description and the proof are accessible to underg
 raduates with a knowledge of basic probability theory.In addition to the s
 implicity\, the approach has significant theoretical and practical implica
 tions: our approach allowed us to resolve the open problem of (Discrete) K
 lee's Measure Problem in the streaming setting and build a state-of-the-ar
 t DNF counter in practice.\n
URL:https://www.tcs.tifr.res.in/web/events/1344
DTSTART;TZID=Asia/Kolkata:20231128T100000
DTEND;TZID=Asia/Kolkata:20231128T113000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1366
DTSTAMP:20231130T100300Z
SUMMARY:Robustness and linear contracts
DESCRIPTION:Speaker: Soumyajit Pyne (TIFR)\n\nAbstract: \nWe consider a gam
 e theoretic model with two players- the principal and the agent. The princ
 ipal knows some actions available to the agent\, but other\, unknown actio
 ns may also exist. The principal evaluates contracts according to their wo
 rst-case performance\, with respect to the actions that may or may not be 
 available to the agent. Under very general circumstances\, the unique opti
 mal contract is linear.\nRobustness and Linear Contracts\n
URL:https://www.tcs.tifr.res.in/web/events/1366
DTSTART;TZID=Asia/Kolkata:20231201T143000
DTEND;TZID=Asia/Kolkata:20231201T153000
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1362
DTSTAMP:20231130T091202Z
SUMMARY:Exploring Size Complexity in Decision Trees
DESCRIPTION:Speaker: Yogesh Dahiya (IMSc Chennai)\n\nAbstract: \nDecision t
 rees are one of the simplest and most basic models  of computation. Given
  a computational task\, in the decision tree  model(query model) of compu
 tation\, the task is computed by adaptively  querying the input while str
 iving to minimize the number of queries  required. While the model is sim
 ple\, it still remains a puzzle with  many unresolved questions. Many sig
 nificant breakthroughs in recent  years have been intricately tied to exp
 loring various facets of the  query model. Discovery of new connections b
 etween proof complexity and  query complexity and the development of quer
 y-to-communication lifting  theorems have played a pivotal role in gettin
 g new results in proof  complexity\, boolean circuit complexity\, and com
 munication complexity.  In the decision tree model\, there are two natura
 l complexity measures  of importance: the depth complexity (the worst-cas
 e number of queries  asked by a query algorithm) and the size complexity 
 (the space  required to store the query algorithm). While significant att
 ention  has been devoted to the former\, the latter remains relatively  
 under-explored.In this talk\, we will investigate the relationship between
  size  complexity and other complexity measures\, and understand the  ad
 vantages that randomness offers in the context of size complexity.  When 
 the computation task is a search problem\, a nuanced usage of  randomness
  by Gat and Goldwasser (ECCC-11) led to the beautiful notion  of pseudo-d
 eterministic mode of computation. Pseudo-deterministic  algorithms are ra
 ndomized algorithms that solve search problems by  almost always providin
 g the same canonical solution (per each input).  They aim to address the 
 inherent variability observed in randomized  algorithms\, which often pro
 duce different correct results across  multiple runs. We will explore the
  interplay between determinism\,  randomness\, and pseudo-determinism con
 cerning size complexity in the  decision tree model. Additionally\, we wi
 ll discuss more generalized  variants of decision trees\, where queries a
 re allowed to be functions  from specific classes rather than ordinary si
 ngle-variable queries.\n
URL:https://www.tcs.tifr.res.in/web/events/1362
DTSTART;TZID=Asia/Kolkata:20231201T160000
DTEND;TZID=Asia/Kolkata:20231201T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1359
DTSTAMP:20231130T095622Z
SUMMARY:Towards Computation- and Communication-Efficient Distributed Learni
 ng
DESCRIPTION:Speaker: Pranay Sharma (Carnegie Mellon University\, Pittsburgh
 \, Pennsylvania)\n\nAbstract: \n\nModern machine learning (ML) systems rel
 y on the data collected at the edge devices to power diverse applications 
 like predictive typing\, personalized recommendations\, and real-time traf
 fic updates. However\, data privacy concerns and network bandwidth constra
 ints preclude gathering the entire dataset at a central location for furth
 er processing. In the past few years\, federated learning (FL) has emerged
  as a natural solution to this problem. The edge devices in FL maintain ex
 clusive control of their data and in return\, shoulder part of the computa
 tional load of the central server. Google and Apple have already deployed 
 FL to improve GBoard and Siri.\n \nIn this talk\, I will discuss my work 
 addressing several challenges in FL. Despite extensive research over the p
 ast few years\, the underlying optimization problems solved by most work a
 re simple minimization. However\, many ML applications\, like GANs\, robus
 t learning\, and reinforcement learning\, can be modeled as min-max proble
 ms. I will first describe my work solving nonconvex min-max problems in a 
 federated setting. In addition to achieving state-of-the-art theoretical c
 omputation-communication guarantees\, this work interestingly even improve
 s the existing centralized methods. Next\, I will also talk about my work 
 on FL systems solving minimization problems\, where I quantify the impact 
 of limited device participation\, where only a small fraction of all the d
 evices may be available at any time. I will then discuss a reinforcement l
 earning problem in a federated setting\, where we prove linear speedup in 
 the presence of Markov noise\, answering an existing open question. Finall
 y\, I will conclude with some future directions I'm excited about and my b
 roader research vision.\n
URL:https://www.tcs.tifr.res.in/web/events/1359
DTSTART;TZID=Asia/Kolkata:20231204T110000
DTEND;TZID=Asia/Kolkata:20231204T120000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1358
DTSTAMP:20231205T044029Z
SUMMARY:Fast Numerical Multivariate Multipoint Evaluation
DESCRIPTION:Speaker: Prahladh  Harsha (TIFR)\n\nAbstract: \nMultipoint eval
 uation is the computational task of evaluating a polynomial given as a lis
 t of coefficients at a given set of evaluation inputs. A straightforward a
 lgorithm for this problem is to just iteratively evaluate the polynomial a
 t each of the inputs. The question of obtaining faster-than-naive (and ide
 ally\, close to linear time) algorithms for this problem is a natural and 
 basic question in computational algebra.\n \nThe classical FFT algorithm 
 gives such an algorithm for the special case of univariate polynomials and
  a well-structured set of evaluation points (say roots of unity). Only as 
 recently as last year\, was the multivariate version of this problem for a
 ll sets of evaluation points resolved for finite fields due to the works o
 f Bhargava\, Ghosh\, Guo\, Kumar & Umans.\n \nThe case of infinite fields
  (eg\, reals\, rationals) is complicated due to subtleties arising from th
 e bit-complexity of the output compelling one to work with either an appro
 ximate version of the problem or an exact version where the algorithm is a
 llowed to run in time nearly-linear in the output size. Only as recently a
 s 2021\, was the univariate version of this problem over infinite fields r
 esolved by Moroz.\n \nIn this talk\, we will show how to extend these res
 ults to obtain similar nearly-linear time results for the multivariate ver
 sion of the problem over infinite fields such as rationals\, reals both in
  the approximate and exact setting.\n \n[Joint work with Sumanta Ghosh\, 
 Simao Herdade\, Mrinal Kumar and Ramprasad Saptharishi]\n
URL:https://www.tcs.tifr.res.in/web/events/1358
DTSTART;TZID=Asia/Kolkata:20231205T160000
DTEND;TZID=Asia/Kolkata:20231205T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1367
DTSTAMP:20231207T030511Z
SUMMARY:Nearly Equitable Allocations Beyond Additivity and Monotonicity
DESCRIPTION:Speaker: Yeshwant Chandrakant  Pandit (TIFR)\n\nAbstract: \nEqu
 itability (EQ) in fair division requires that items be allocated such that
  all agents value the bundle they receive equally. With indivisible items\
 , an equitable allocation may not exist\, and hence we instead consider a 
 meaningful analog\, EQx\, that requires equitability up to any item. EQx a
 llocations exist for monotone\, additive valuations. However\, if (1) the 
 agents' valuations are not additive or (2) the set of indivisible items in
 cludes both goods and chores (positively and negatively valued items)\, th
 en before the current work it was not known whether EQx allocations exist 
 or not.\nWe study both the existence and efficient computation of EQx allo
 cations. (1) For monotone valuations (not necessarily additive)\, we show 
 that EQx allocations always exist. Also\, for the large class of weakly we
 ll-layered valuations\, EQx allocations can be found in polynomial time. F
 urther\, we prove that approximately EQx allocations can be computed effic
 iently under general monotone valuations. (2) For non-monotone valuations\
 , we show that an EQx allocation may not exist\, even for two agents with 
 additive valuations. Under some special cases\, however\, we show the exis
 tence and efficient computability of EQx allocations. This includes the ca
 se of two agents with additive valuations where each item is either a good
  or a chore\, and there are no mixed items.\nThe focus of this talk will b
 e on the results obtained under monotone valuations. This is joint work wi
 th Siddharth Barman(IISC\, Bangalore)\, Umang Bhaskar(TIFR\, Mumbai) and S
 oumyajit Pyne(TIFR\, Mumbai).\n
URL:https://www.tcs.tifr.res.in/web/events/1367
DTSTART;TZID=Asia/Kolkata:20231208T160000
DTEND;TZID=Asia/Kolkata:20231208T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1365
DTSTAMP:20231201T042513Z
SUMMARY:Sparsification: Graphs\, CSPs and Codes
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Paulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nA sparsification of a structure\
 , with respect to a class of queries\, produces a compressed representatio
 n of the structure while answering every query in the class approximately 
 correctly. The seminal example of sparsification is "graph sparsification 
 with respect to cut queries"\, due to works of Karger and Benczur and Karg
 er from the 1990s\, showing that every graph can be compressed to near-lin
 ear size (in the number of nodes in the graph) while approximately capturi
 ng the size of every cut in the graph. In 2015 Kogan and Krauthgamer gener
 alized the notion of sparsification to all Constraint Satisfaction Problem
 s (CSPs) --- here the structure to be compressed is an instance of the CSP
  on n variables and a query is an assignment to the n variables\, and the 
 goal thus is to approximately determine the number of constraints satisfie
 d by the queried assignment. Several follow up works gave some non-trivial
  CSPs that allow for near linear (in n) sparsifications\, including classi
 fication of all binary CSPs (where each constraint applies to two variable
 s) that allow such sparsification\, but the general picture seemed wide op
 en.In our works we introduce a new class of sparsification problems\, name
 ly code sparsification\, where the structure to be preserved is a linear e
 rror correcting code\; the query is a message\, and the goal is to compute
  the approximate weight of the encoding of the message. We show that this 
 class of problems gives the right language to abstract the techniques of K
 arger and Benczur and Karger --- and indeed all codes can be sparsified to
  length nearly linear in the number of message bits. This generalization a
 lready resolves some basic questions in CSP sparsification. A further gene
 ralization to additive codes over finite abelian groups gives even powerfu
 l results and in particular completely classifies the class of symmetric B
 oolean CSPs that allow nearly linear sized sparsification. (Prior to our w
 ork even the case of sparsification of 3-XOR constraints was open.) A key 
 question left open by our work is the algorithmic challenge of finding the
  sparsification efficiently --- our work only proves the existence of thes
 e.Based on joint works with Sanjeev Khanna (U. Penn.) and Aaron (Louie) Pu
 tterman (Harvard).\n
URL:https://www.tcs.tifr.res.in/web/events/1365
DTSTART;TZID=Asia/Kolkata:20231211T143000
DTEND;TZID=Asia/Kolkata:20231211T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1335
DTSTAMP:20231130T075535Z
SUMMARY:Optimal Flexible Consensus and its Application to Ethereum
DESCRIPTION:Speaker: Srivatsan Sridhar (Stanford University\, U.S.A.)\n\nAb
 stract: \nClassic BFT consensus protocols guarantee safety and liveness fo
 r all clients if fewer than one-third of replicas are faulty. However\, in
  applications such as high-value payments\, some clients may want to prior
 itize safety over liveness. Flexible consensus allows each client to opt f
 or safety against more than one-third faulty replicas\, albeit at the expe
 nse of liveness under fewer faults. I will present the first construction 
 that allows the optimal safety-liveness tradeoff for every client simultan
 eously. This construction is modular and is realized as an add-on applied 
 on top of an existing consensus protocol. I adapt this construction to the
  existing Ethereum protocol in the form of optimal flexible confirmation r
 ules that clients can adopt unilaterally without requiring system-wide cha
 nges. I will show results and insights from implementing the confirmation 
 rules on an Ethereum client.\nThis talk is based on a paper set to appear 
 at IEEE S&P 2024 and is a joint work with Joachim Neu\, Lei Yang\, and Dav
 id Tse.\n
URL:https://www.tcs.tifr.res.in/web/events/1335
DTSTART;TZID=Asia/Kolkata:20231212T160000
DTEND;TZID=Asia/Kolkata:20231212T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1363
DTSTAMP:20231201T042609Z
SUMMARY:Deciding Conjugacy of a Rational Relation
DESCRIPTION:Speaker: Amaldev Manuel (IIT Goa)\n\nAbstract: \nRational relat
 ions are precisely those relations on words that are definable by transduc
 ers\, i.e.\, automata with output. Two words are conjugate if they are cyc
 lic shifts of each other\, or equivalently\, of the form xy and yx for som
 e words x and y. The conjugacy problem for rational relations asks if a gi
 ven rational relation is conjugate. We show that the problem is decidable 
 in exponential time (and polytime for sumfree rational expressions). The p
 roof relies on a generalisation of a classic theorem by Lyndon-Schützenbe
 rger from word combinatorics. In the talk\, we will discuss some historic 
 applications of the conjugacy problem\, our particular motivation to study
  the problem\, and a brief sketch of the proof. Joint work with C. Aiswary
 a (CMI) and Saina Sunny (IIT GOA)A draft of the paper is available 
 at: https://arxiv.org/abs/2307.06777\n
URL:https://www.tcs.tifr.res.in/web/events/1363
DTSTART;TZID=Asia/Kolkata:20231213T160000
DTEND;TZID=Asia/Kolkata:20231213T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1370
DTSTAMP:20231212T081930Z
SUMMARY:Online Weighted Facility Location
DESCRIPTION:Speaker: Arghya Chakraborty (TIFR)\n\nAbstract: \nThe classic o
 nline facility location problem deals with finding the optimal set of faci
 lities in an online fashion when demand requests arrive one at a time and 
 facilities need to be opened to service these requests. In this work\, we 
 study a variant where each demand request is a pair (x\,w) where x is the 
 standard location of the demand while w is the corresponding weight of the
  request. The cost of servicing request (x\,w) at facility F is w⋅d(x\,F
 ). For this variant\, given n requests\, we present an online algorithm at
 taining a competitive ratio of O(log n) in the secretarial model for the w
 eighted requests and show that it is optimal.\nThis is joint work with Pro
 f. Rahul Vaze.\n
URL:https://www.tcs.tifr.res.in/web/events/1370
DTSTART;TZID=Asia/Kolkata:20231214T110000
DTEND;TZID=Asia/Kolkata:20231214T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1369
DTSTAMP:20231216T151338Z
SUMMARY:STCS Farewell party for Jaikumar Radhakrishnan (14 Dec 2023)
DESCRIPTION:Speaker: \n\nAbstract: \nProf. Jaikumar Radhakrishnan's farewel
 l party on December 14. Please find below the schedule for the event.https
 ://www.tcs.tifr.res.in/~jaikumar-farewell/\n
URL:https://www.tcs.tifr.res.in/web/events/1369
DTSTART;TZID=Asia/Kolkata:20231214T134500
DTEND;TZID=Asia/Kolkata:20231214T170000
LOCATION:AG-66 (Lecture Theatre)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1364
DTSTAMP:20231205T090534Z
SUMMARY:Identifiability of Product of Experts Models
DESCRIPTION:Speaker: Leonard J. Schulman (Caltech)\n\nAbstract: \nProduct o
 f experts (PoE) are layered networks in which the value at each node is an
  AND (or product) of the values (possibly negated) at its inputs. These we
 re introduced as a neural network architecture that can efficiently learn 
 to generate high-dimensional data which satisfy many low-dimensional const
 raints---thereby allowing each individual expert to perform a simple task.
  PoEs have found a variety of applications in learning. More recently\, th
 ey have arisen in the theory of causal networks.\n \nWe study the problem
  of identifiability of a product of experts model having a layer of binary
  latent variables\, and a layer of binary observables that are iid conditi
 onal on the latents. The previous best upper bound on the number of observ
 ables needed to identify the model was exponential in the number of parame
 ters. We show: (a) When the latents are uniformly distributed\, the model 
 is identifiable with a number of observables equal to the number of parame
 ters (and hence best possible). (b) In the more general case of arbitraril
 y distributed latents\, the model is identifiable for a number of observab
 les that is still linear in the number of parameters (and within a factor 
 of two of best-possible). The proofs rely on root interlacing phenomena fo
 r some special three-term recurrences.\n \nBased on joint work with Spenc
 er Gordon\, Manav Kant\, Eric Ma and Andrei Staicu.\n
URL:https://www.tcs.tifr.res.in/web/events/1364
DTSTART;TZID=Asia/Kolkata:20231215T110000
DTEND;TZID=Asia/Kolkata:20231215T120000
LOCATION:AG-80
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1374
DTSTAMP:20231226T083933Z
SUMMARY:Maximal determinant problem for $l_p$ normed spaces
DESCRIPTION:Speaker: Dr. Arun Maiti (Thapar Institute of Engineering & Tech
 nology\, Punjab)\n\nAbstract: \nHadamard's maximum determinant problem ask
 s for maximas of the determinant on matrices with entries either -1 or 1.\
 nIn this talk\, I will introduce a generalisation of this problem for matr
 ices with rows having unit $l_p$ norm. The solution to this problem for sm
 all orders will be presented. I will further relate it to the problem of f
 inding Auerbach bases of $l_p$ spaces. Some new results and conjectures on
  this problem will be discussed.\n
URL:https://www.tcs.tifr.res.in/web/events/1374
DTSTART;TZID=Asia/Kolkata:20231227T160000
DTEND;TZID=Asia/Kolkata:20231227T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1368
DTSTAMP:20240102T092014Z
SUMMARY:Efficient Importance Scenario Generation for Optimization with Rare
  Events
DESCRIPTION:Speaker: Anand Deo (IIM Bangalore)\n\nAbstract: \nThis talk pro
 vides an overview of how one may employ importance sampling effectively as
  a tool for solving stochastic optimization formulations incorporating tai
 l risk measures such as Conditional Value-at-Risk. Approximating the tail 
 risk measure by its sample average approximation\, while appealing due to 
 its simplicity and universality in use\, requires a large number of sample
 s to be able to arrive at risk-minimizing decisions with high confidence. 
 This is primarily due to the rarity with which the relevant tail events ge
 t observed in the samples. In simulation\, Importance Sampling is among th
 e most prominent methods for substantially reducing the sample requirement
  while estimating probabilities of rare events. Can importance sampling be
  used for optimization as well? If so\, what are the ingredients required 
 for making importance sampling an effective tool for optimization formulat
 ions involving rare events? We provide an introductory overview of the two
  key ingredients in this regard\, namely\, (i) how one may arrive at a cha
 nge of measure prescription at every decision\, and (ii) the prominent tec
 hniques available for integrating such a prescription within a solution pa
 radigm for stochastic optimization formulations.\nThe talk is based on sev
 eral joint works with Karthyek Murthy.\n
URL:https://www.tcs.tifr.res.in/web/events/1368
DTSTART;TZID=Asia/Kolkata:20240102T160000
DTEND;TZID=Asia/Kolkata:20240102T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1379
DTSTAMP:20240103T081941Z
SUMMARY:One Shot Non-Catalytic Distributed Purity Distillation
DESCRIPTION:Speaker: Dr. Sayantan Chakraborty (Centre for Quantum Technolog
 ies\, National University of Singapore)\n\nAbstract: \nPure states are an 
 important resource in many quantum information processing protocols. Howev
 er\, even making a fixed pure state\, say $\\vert 0 \\rangle$\, in the lab
 oratory requires a considerable amount of effort. Often one ends up with a
  mixed state $\\rho$ whose classical description is nevertheless known. He
 nce it is important to develop protocols that extract a fixed pure state f
 rom a known mixed state. In this work\, we study the problem of extracting
  a fixed pure state $\\vert 0 \\rangle^{A'} \\vert{0}\\rangle^{B'}$ from a
  known pure state $\\rho^{AB}$ distributed between two parties $A$ and $B$
 . Here\, $A'$\, $B'$ are subspaces of $A$\, $B$ and the total amount of pu
 rity extracted is $\\log |A'| + \\log |B'|$. The parties can borrow local 
 pure ancilla\, apply local unitary operations and send a message from $A$ 
 to $B$ through a dephasing channel. If local pure ancilla is borrowed\, it
  must be subtracted in order to properly account for the purity extracte
 d. We obtain the most efficient achievable bounds on one shot distributed 
 purity extraction\, in terms of the rate of local ancilla borrowed by the 
 protocol\, while distilling pure qubits at the best known rate. Our protoc
 ols borrow little to no local pure ancilla. Our bounds improve upon the ex
 isting bounds for this problem in both one shot as well as asymptotic iid 
 settings. In particular they subsume all the asymptotic iid results of Dev
 etak and Krovi-Devetak. In addition\, we derive upper bounds for the rate 
 of distillation in the one shot setting\, which nearly match our achievabl
 e bounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1379
DTSTART;TZID=Asia/Kolkata:20240103T160000
DTEND;TZID=Asia/Kolkata:20240103T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1377
DTSTAMP:20240103T032207Z
SUMMARY:List Decoding of Tanner and Expander Amplified Codes from Distance 
 Certificates
DESCRIPTION:Speaker: Mr. Shashank Srivastava (Toyota Technological Institut
 e at Chicago (TTIC))\n\nAbstract: \nIn the theory of error-correcting code
 s\, list decoding is a relaxation of unique decoding useful for tolerating
  higher levels of noise. Design of list decoding algorithms for algebraic 
 codes\, such as Reed-Solomon\, has found numerous applications in error co
 rrection\, as well as in complexity theory and pseudorandomnness. However\
 , we know of very few techniques for list decoding algorithms when the cod
 e may not have such algebraic structure\, such as Tanner codes which are d
 efined using sparse expander graphs.\n \nIn this talk\, I will describe h
 ow continuous relaxations based on the Sum-of-Squares hierarchy can be use
 d to design the first list decoding algorithm for Tanner codes of Sipser-S
 pielman [IEEE Trans. Inf. Theory 1996]. The techniques include a novel pro
 of of the Johnson bound for arbitrary codes\, distance proofs for pseudoco
 dewords\, and correlation rounding for convex hierarchies. I will also dis
 cuss extensions to a distance amplification scheme of Alon-Edmonds-Luby [F
 OCS 1995].\n \nBased on joint work with Fernando Granha Jeronimo and Madh
 ur Tulsiani.\n
URL:https://www.tcs.tifr.res.in/web/events/1377
DTSTART;TZID=Asia/Kolkata:20240104T160000
DTEND;TZID=Asia/Kolkata:20240104T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1376
DTSTAMP:20240103T041211Z
SUMMARY:How powerful are homogeneous algebraic formulas?
DESCRIPTION:Speaker: Prof. Nutan Limaye (IT University of Copenhagen)\n\nAb
 stract: \nProving explicit lower bounds on the size of algebraic formulas 
 is a long-standing open problem in the area of algebraic complexity theory
 . Recent results in the area have indicated a strategy for attacking this 
 question: show that we can convert a general algebraic formula to a homoge
 neous algebraic formula with moderate blow-up in size\, and prove strong l
 ower bounds against the latter model. In this talk we will discuss the fea
 sibility of the above strategy. Homogeneous formula lower bounds. We will 
 show lower bounds against ‘weighted’ homogeneous formulas of arbitrary
  depth. This is the first such lower bound for arbitrary depth formulas. T
 his gives a strong indication that lower bounds against homogeneous formul
 as may be within reach.Efficient homogenization. We show that any formula 
 F for a homogeneous polynomial of degree d can be homogenized over fields 
 of characteristic 0 as long as $d = s^{o(1)}$. Such a result was previousl
 y only known when $d = (\\log s)^{1+o(1)}$ (Raz (J. ACM (2013))).Non-commu
 tative homogenization. A recent result of Dutta\, Gesmundo\, Ikenmeyer\, J
 indal and Lysikov (2022) implies that to homogenize algebraic formulas of 
 any depth\, it suffices to homogenize non-commutative algebraic formulas o
 f depth just 3. We are able to show strong lower bounds against such homog
 enization\, suggesting barriers for this approach. The talk is based on a 
 joint work with Hervé Fournier\, Srikanth Srinivasan\, and Sébastien Tav
 enas. \n
URL:https://www.tcs.tifr.res.in/web/events/1376
DTSTART;TZID=Asia/Kolkata:20240105T143000
DTEND;TZID=Asia/Kolkata:20240105T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1380
DTSTAMP:20240104T091221Z
SUMMARY:Deterministic Algorithms for Low-Degree Factors of Constant-Depth C
 ircuits
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nFor every const
 ant d\, we design a subexponential time deterministic algorithm that takes
  as input a multivariate polynomial f given as a constant depth algebraic 
 circuit over the field of rational numbers\, and outputs all irreducible f
 actors of f of degree at most d together with their respective multiplicit
 ies. Moreover\, if f is a sparse polynomial\, then the algorithm runs in q
 uasipolynomial time. Our results are based on a more fine-grained connecti
 on between polynomial identity testing (PIT) and polynomial factorization 
 in the context of constant degree factors and rely on a clean connection b
 etween divisibility testing of polynomials and PIT due to Forbes and on su
 bexponential time deterministic PIT algorithms for constant depth algebrai
 c circuits from the recent work of Limaye\, Srinivasan and Tavenas.\nThis 
 will be a conference-style short talk of about 20 minutes\, with questions
  in the end.\n
URL:https://www.tcs.tifr.res.in/web/events/1380
DTSTART;TZID=Asia/Kolkata:20240105T160000
DTEND;TZID=Asia/Kolkata:20240105T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1371
DTSTAMP:20240109T044521Z
SUMMARY:Of the data\, by the data\, for the data: an algorithmic viewpoint
DESCRIPTION:Speaker: Ashok Vardhan Makkuva (École Polytechnique Fédérale
  de Lausanne (EPFL))\n\nAbstract: \nRanging from arts to science\, in disc
 iplines traditionally considered as bastions of human ingenuity\, data-dri
 ven algorithms have led remarkable breakthroughs in recent years through C
 hatGPT (natural languages)\, AlphaGo (game playing)\, and AlphaFold (biolo
 gy). With their ever growing prominence and ubiquity\, there is a growing 
 consensus that the need of the hour is a fundamental understanding of the 
 success and pitfalls of these algorithms. To this end\, my research adopts
  an interdisciplinary approach to design mathematical foundations and prin
 cipled algorithms for problems of great practical relevance. While advanci
 ng the success frontiers of data-driven methods\, this approach offers a u
 nique mathematical lens to study and understand them.\nIn this talk\, I wi
 ll present my contributions along these themes in the fields of informatio
 n theory\, machine learning\, and optimization. Through our work on KO cod
 es\, I will demonstrate how data-driven algorithms can discover state-of-t
 he-art codes for wireless communication\, a fundamental problem at the hea
 rt of information and coding theory. This research highlights the great po
 tential these methods hold for the design of next generation communication
  systems. Next\, I will present our novel algorithmic contribution in opti
 mal transport where we design an efficient and reliable algorithm to learn
  the optimal transport map between two distributions. These key ideas have
  broad applications in biology and medicine including cell perturbation an
 alysis and drug discovery. Finally\, I will present our ongoing work on de
 signing a solid set of theoretical and algorithmic tools to study large la
 nguage models (LLMs) and transformers. Despite their impressive performanc
 e\, our understanding of these models is still in infancy and my main goal
  here is to develop new insights into their inner workings and faster and 
 efficient training algorithms. I will conclude with my broader research vi
 sion in the realm of data science.\n \nAshok is a postdoctoral researcher
  at EPFL with Michael Gastpar. He obtained his PhD in ECE from the Univers
 ity of Illinois at Urbana-Champaign in August 2022\, with Pramod Viswanath
  and Sewoong Oh. He obtained his Masters in ECE with Yihong Wu also from U
 IUC in 2017. Earlier he graduated from IIT Bombay with a B.Tech. in EE and
  Minors in Mathematics working with Vivek Borkar. His research interests a
 re in foundations of data science in topics including machine learning\, i
 nformation theory\, optimization\, and statistics. He is a recipient of Be
 st Paper Award from ACM MobiHoc 2019. He is also a recipient of several gr
 aduate student awards and fellowships including Joan and Lalit Bahl Fellow
 ship (twice)\, Sundaram Seshu International Student Fellowship\, finalist 
 for the Qualcomm Innovation Fellowship 2018.\n
URL:https://www.tcs.tifr.res.in/web/events/1371
DTSTART;TZID=Asia/Kolkata:20240109T160000
DTEND;TZID=Asia/Kolkata:20240109T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1372
DTSTAMP:20240102T061417Z
SUMMARY:The transformation of regular expressions into finite automata: old
  and new results
DESCRIPTION:Speaker: Jacques Sakarovitch (IRIF\, CNRS/Paris Cité Universit
 y)\n\nAbstract: \nNot many results in Computer Science are recognised to b
 e as basic and fundamental as Kleene Theorem.  It states the equality of 
 two sets of objects that we call now languages.  A slight change of focus
  on this result shows how it is essentially the combination of two familie
 s of algorithms: algorithms that transform a finite automaton into a regul
 ar expression on one hand and algorithms that build a finite automaton fro
 m a regular expression on the other.In this talk\, I shall consider the al
 gorithms of the latter family\, a much laboured subject of both theoretica
 l and practical interests. I shall present three different constructions\,
  classically attributed to Thompson\, Glushkov\, and Brzozowski-Antimirov 
 respectively\, and their relationships.We shall then see how the extension
  of Kleene Theorem beyond languages: to subsets of arbitrary monoids first
  and second to subsets with multiplicity\, leads to a modification of the 
 construction for the first one and to a radical transformation of the proo
 f for the third.All recent results were obtained in joint works wi
 th Sylvain Lombardy.\n
URL:https://www.tcs.tifr.res.in/web/events/1372
DTSTART;TZID=Asia/Kolkata:20240111T160000
DTEND;TZID=Asia/Kolkata:20240111T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1383
DTSTAMP:20240111T083135Z
SUMMARY:On the degree of polynomials computing square roots mod p
DESCRIPTION:Speaker: Shanthanu  Suresh Rai (TIFR)\n\nAbstract: \nFor an odd
  prime p\, we say that a polynomial f(X) in F_p[X] computes square roots m
 od p if for all non-zero perfect squares a\, f(a)^2 = a (mod p).Problem: C
 onstruct a low degree polynomial f(X) that compute square roots mod p.It c
 an be easily shown that f(X) has degree between p/4 and p/2. When p = 3 mo
 d 4\, it is well-known that f(X)=X^{(p+1)/4} computes square roots\, and t
 he degree is as low as possible.When p = 1 mod 4\, previously no non-trivi
 al lower bound for degree of f(X) were known. In the paper\, the authors s
 how that f(X) has degree at least (p-1)/3. The main ingredient in the proo
 f is the following general lemma: powers of low degree polynomial cannot h
 ave too many consecutive zero coefficients.In the other direction\, the au
 thors show that for infinitely many p = 1 mod 4\, the degree of the polyno
 mial computing square roots can be (1/2-Ω(1))p.Paper link: https://eccc.
 weizmann.ac.il/report/2023/177/downloadAuthors: Kiran Kedlaya\, Swastik Ko
 pparty\n
URL:https://www.tcs.tifr.res.in/web/events/1383
DTSTART;TZID=Asia/Kolkata:20240112T143000
DTEND;TZID=Asia/Kolkata:20240112T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1384
DTSTAMP:20240116T043225Z
SUMMARY:On Approximability of Satisfiable CSPs
DESCRIPTION:Speaker: Prof. Amey Bhangale (University of California\, Rivers
 ide)\n\nAbstract: \nConstraint Satisfaction Problems (CSPs) are among the 
 most well-studied problems in Computer Science. The satisfiability problem
  for CSP asks whether an instance of CSP has a fully satisfying assignment
 \, i.e. an assignment that satisfies all constraints. This problem is know
 n to be in class P or is NP-complete by the recently proved Dichotomy Theo
 rem of Bulatov and Zhuk. For a given k-ary predicate P:[q]^k−>{0\,1}\, w
 here P−1(1) denotes the set of satisfying assignments\, the problem CSP(
 P) has every local constraints of the form the predicate P applied to the 
 ordered set of k variables (or literals).\nA most natural question is to a
 sk for the precise threshold α(P) less than 1 for every NP-complete CSP(P
 ) such that (i) there is a polynomial-time algorithm that finds an assignm
 ent satisfying α(P) fraction of the constraints on a satisfiable instance
  and (ii) for every \\epsilon greater than 0\, finding an (α(P)+ϵ) satis
 fying assignment is NP-hard. It is reasonable to hypothesize that such a t
 hreshold exists for every NP-complete CSP(P). This natural question is wid
 e open\, though such thresholds are known for some specific predicates (e.
 g.\, 7/8 for 3SAT by Hastad). \nThe talk will present recent work initiat
 ing a systematic study of this question\, a relevant analytic hypothesis a
 nd some progress on it\, and a work of Raghavendra that answers the questi
 on on almost-satisfiable instances. The talk will be based on a series of 
 joint works with Subhash Khot and Dor Minzer.\n
URL:https://www.tcs.tifr.res.in/web/events/1384
DTSTART;TZID=Asia/Kolkata:20240116T160000
DTEND;TZID=Asia/Kolkata:20240116T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1386
DTSTAMP:20240121T034558Z
SUMMARY:On the projected Aubry set of the rate function associated with lar
 ge deviations for stochastic approximations
DESCRIPTION:Speaker: Prof. Henrik Hult (Professor in Mathematical Statistic
 s)\n\nAbstract: \nWe consider the problem of minimizing an action potentia
 l that arises from large deviation theory for stochastic approximations. T
 he solutions to the minimizing problem satisfy\, in the sense of a viscosi
 ty solution\, a Hamilton-Jacobi equation. From weak KAM theory\, we know t
 hat these viscosity solutions are characterised by the projected Aubry set
 . The main result of this paper is that\, for a specific rate function cor
 responding to a stochastic approximation algorithm\, we prove that the pro
 jected Aubry set is equal to the forward limit set to the limit ODE. \n
URL:https://www.tcs.tifr.res.in/web/events/1386
DTSTART;TZID=Asia/Kolkata:20240122T143000
DTEND;TZID=Asia/Kolkata:20240122T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1373
DTSTAMP:20231226T095541Z
SUMMARY:Optimized Decision Making via Active Learning of  Stochastic Hamilt
 onians
DESCRIPTION:Speaker: Prof. Chandrajit Bajaj (University of Texas at Austin)
 \n\nAbstract: \nA Hamiltonian represents the energy of a dynamical system 
 in phase space with coordinates of position and momentum. The Hamilton’s
  equations of motion are obtainable as coupled symplectic differential equ
 ations.  In this talk I shall show how optimized decision making (action 
 sequences) can be obtained via a reinforcement learning problem wherein th
 e agent interacts with the unknown environment to simultaneously learn a H
 amiltonian surrogate and the optimal action sequences using Hamilton dynam
 ics\, by invoking the Pontryagin Maximum Principle. We use optimal control
  theory to define an optimal control gradient flow\, which guides the rein
 forcement learning process of the agent to progressively optimize the Hami
 ltonian while simultaneously converging to the optimal action sequence. Ex
 tensions to stochastic Hamiltonians leading to stochastic action sequences
  and the free-energy principle shall also be discussed.\nThis is joint wor
 k with my students Taemin Heo\, Minh Nguyen.\n
URL:https://www.tcs.tifr.res.in/web/events/1373
DTSTART;TZID=Asia/Kolkata:20240123T160000
DTEND;TZID=Asia/Kolkata:20240123T170000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1375
DTSTAMP:20240124T042057Z
SUMMARY:Formal Methods for Software Reliability and Synthesis
DESCRIPTION:Speaker: Dr. Ashish Mishra (Purdue University (CS))\n\nAbstract
 : \nBuilding reliable software has been a classical goal in Computer Scien
 ce.The most basic premise of my research is derived from this goal. Can we
  make programs safe and reliable using formal techniques while making prog
 ramming as a discipline more democratic and accessible to the masses?\n
 In this talk\, I will begin by highlighting some of these overarching rese
 arch interests and directions.I will primarily present two of my recent wo
 rks highlighting the effective use of Refinement types and SMT-based tech
 niques for the _verification_ and _synthesis_ of programs.(i) The first is
  a specification-guided _synthesis_ procedure that uses Hoare-style pre- a
 nd post-conditions to express fine-grained effects of potential library co
 mponent candidates to drive a bi-directional synthesis search strategy. It
  integrates a conflict-driven learning procedure into the synthesis algori
 thm that provides a semantic characterization of previously encountered un
 successful search paths used to prune possible candidates' space as synthe
 sis proceeds.(ii) The second work is a new _Refinement-Type_ system called
  _Coverage Type_ which adapts the recent work in Incorrectness Logic to th
 e specification and automated verification of test input generators used i
 n modern property-based testing systems. Specifications are expressed in t
 he language of refinement types\, augmented with coverage types\, types th
 at reflect underapproximate constraints on program behavior.I will conclud
 e with some of my completed and ongoing works and future research directio
 ns.Particularly\, I will discuss three potential paths I am taking:\n(i) O
 ur new deductive CBS using _Semantic Similarity Reduction_ based on a nove
 l definition of a _Qualified Tree Automata_.\n(ii) Utilizing _underapproxi
 mate_ reasoning for deductive synthesis.\n(iii) Applying program synthesis
  to _novel domains_ like Robotics and the need for combining Neural and Sy
 mbolic program synthesis approaches\, aka _Neurosymbolic program synthesis
 _.\nShort Bio:\nAshish Mishra is a Postdoctoral Researcher at Purdue Unive
 rsity\, where he works with Professor Suresh Jagannathan in the areas of
  Programming Languages\, Program Verification\, and Program Synthes
 is.Ashish obtained his Ph.D. from the Indian Institute of Science\, where
  he worked under the supervision of Professor Y. N. Srikant.In a
 ddition to his work in Computer Science\, Ashish is also interested in ap
 plying technology to public policies and solving social problems. He is c
 urrently involved with several Indian NGOs such as PARI (People's Archive
  for Rural India)\, Mosali (a startup trying to bring women into workforc
 e)\, and others that are involved in Media Monitoring and Research.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1375
DTSTART;TZID=Asia/Kolkata:20240130T160000
DTEND;TZID=Asia/Kolkata:20240130T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1390
DTSTAMP:20240202T033112Z
SUMMARY:The Devil's Chessboard problem and the Hamming code
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nHere's a proble
 m. The devil has captured two people and is playing a game with them for t
 heir freedom. Person A will be presented with a chessboard with a penny in
  each square (64 total)\, with each penny either heads up or tails up rand
 omly. The devil will choose a particular square and point it out to Person
  A. Person A then chooses a single square\, and flips the penny in that sq
 uare. Afterward\, Person A is sent away and Person B is brought forward. B
 ased on the new state of the board\, Person B must point out the same squa
 re that the devil did in order to win. The two people can devise a strateg
 y beforehand\, but cannot communicate once the game starts. How can they w
 in?\nHere's another problem. Alice wants to transmit a sequence of bits to
  Bob through a communication channel. But Eve has the ability to discreetl
 y flip at most a single bit in the message that Alice sends to Bob. Is the
 re a way for Alice to add some redundancy in her messages so that Bob ca
 n figure out when a bit has been flipped and also correct it?\nThese two p
 roblems are connected\, and we will see how.\n
URL:https://www.tcs.tifr.res.in/web/events/1390
DTSTART;TZID=Asia/Kolkata:20240202T160000
DTEND;TZID=Asia/Kolkata:20240202T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1387
DTSTAMP:20240201T032448Z
SUMMARY:Optimal Server Allocation for Flexible Multi-Server Jobs with Conca
 ve Speed-up
DESCRIPTION:Speaker: Prof. Arpan Mukhopadhyay (University of Warwick\, UK)\
 n\nAbstract: \nThe majority of jobs submitted to modern computing clusters
  and data centres are capable of running on a flexible number of computing
  cores or servers. We refer to such jobs as flexible multi-server jobs.  
 Although allocating more servers to a job results in a higher speed-up in 
 the job's execution\, it reduces the number of servers available to future
  jobs. Furthermore\, the speed-up obtained by a job is typically a concave
 \, increasing function of the number of servers allocated to it. So a natu
 ral question in this setting is: how to optimally allocate servers to jobs
  such that average time a job spends in the system is minimised? This is t
 he key question that we shall address in this talk by modelling the system
  as a loss system where jobs not finding any servers available upon entry 
 are blocked. We shall discuss server allocation schemes which result in th
 e minimum average sojourn time of accepted jobs while ensuring that the bl
 ocking probability of jobs vanishes as the system becomes large (i.e.\, al
 l jobs are accepted in the limiting system). We shall consider settings wi
 th both linear and sub-linear speed-up functions. We shall also consider s
 ettings where the jobs have limited and full system access.\nThe talk will
  be based on joint works with Samira Ghanbarian (uWaterloo)\, Ravi R. Mazu
 mdar (uWaterloo)\, and Fabrice Guillemin (Orange Labs\, France).\n \nShor
 t Bio:\nDr. Arpan Mukhopadhyay is currently an Assistant Professor in the 
 Department of Computer Science at the University of Warwick\, U.K. His res
 earch interests include applied probability\, performance analysis of comp
 uter and communication networks\, and distributed network algorithms. He h
 as received Best Paper Awards at IFIP Performance 2015 and the Internation
 al Teletraffic Congress (ITC) 2015. He was also awarded the Rising Scholar
  Award at the International Teletraffic Congress 2018 for his contribution
 s to mean-field analysis of large heterogeneous networks.\n
URL:https://www.tcs.tifr.res.in/web/events/1387
DTSTART;TZID=Asia/Kolkata:20240205T113000
DTEND;TZID=Asia/Kolkata:20240205T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1385
DTSTAMP:20240125T054532Z
SUMMARY:Quantum Statistical Inference
DESCRIPTION:Speaker: Dr. Samriddha Lahiry (Harvard University\, Cambridge)\
 n\nAbstract: \nQuantum state estimation is a fundamental problem in quantu
 m information theory with applications in quantum computing and communicat
 ion. To determine the state of a quantum system\, researchers often perfor
 m measurements on a set of identically prepared quantum states\, which are
  indexed by a parameter. These measurements provide information not only a
 bout the parameter itself but also about the quantum states. While questio
 ns related to optimal quantum measurements can be elegantly formulated in 
 the language of mathematical statistics\, the underlying non-commutative s
 tructure yields inferential results that are distinctly non-trivial compar
 ed to their counterparts in classical statistics. Furthermore\, in contras
 t to classical models\, where estimates are constructed solely based on me
 asurement outcomes\, quantum models introduce an additional layer of compl
 exity because the optimal estimator depends on the choice of measurement a
 s well. In classical statistics\, a fundamental paradigm involves approxim
 ating complex models with simpler ones. One commonly establishes asymptoti
 c equivalence between i.i.d. models\, characterized by a local parameter\,
  and a Gaussian shift model. This approximation\, known as local asymptoti
 c normality (LAN)\, facilitates the construction of an estimator based on 
 a procedure in the Gaussian model\, offering comparable risk bounds. Notab
 ly\, local asymptotic equivalence can be extended to quantum scenarios\, l
 inking quantum i.i.d. models with quantum Gaussian models. In this context
 \, we obtain optimal estimators in the complex former models based on opti
 mal estimators in the simpler latter models.\nShort Bio:\nSamriddha Lahir
 y is a postdoctoral fellow at Harvard University in the Department of Stat
 istics. He received his Ph.D. in Statistics from Cornell University in 202
 2. His research focuses on asymptotic methods in quantum statistical infer
 ence and high-dimensional statistics.\n
URL:https://www.tcs.tifr.res.in/web/events/1385
DTSTART;TZID=Asia/Kolkata:20240206T160000
DTEND;TZID=Asia/Kolkata:20240206T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1392
DTSTAMP:20240209T052522Z
SUMMARY:Wyner's common Information
DESCRIPTION:Speaker: Malhar Ajit  Managoli (TIFR)\n\nAbstract: \nGiven two 
 dependent random variables X and Y\, it is interesting to ask how much inf
 ormation is present in both of them. Mutual information is the typical mea
 sure of "common" information\; however\, it is not useful in all situation
 s. Wyner's common information is another such measure which shows up in ma
 ny situations.In this talk we will see the the definition\, some propertie
 s\, and two operational interpretations of Wyner's common information.\n
URL:https://www.tcs.tifr.res.in/web/events/1392
DTSTART;TZID=Asia/Kolkata:20240209T160000
DTEND;TZID=Asia/Kolkata:20240209T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1388
DTSTAMP:20240125T064217Z
SUMMARY:New Lower Bounds for Set-Multilinear Branching Programs
DESCRIPTION:Speaker: Mr. Deepanshu Kush (University of Toronto)\n\nAbstract
 : \nIn this talk\, we will discuss new lower bounds for the model of sum 
 of ordered set-multilinear algebraic branching programs. The significance 
 of these lower bounds is underscored by the recent work of Bhargav\, Dwive
 di\, and Saxena (2023)\, which showed that super-polynomial lower bounds a
 gainst this model -- for a set-multilinear polynomial of sufficiently low 
 degree -- would imply super-polynomial lower bounds against general ABPs\
 , thereby resolving Valiant's longstanding conjecture that the permanent p
 olynomial cannot be computed efficiently by ABPs. We will discuss our new 
 results which "almost" meet this low-degree demand. This is joint work wit
 h Prerona Chatterjee\, Shubhangi Saraf\, and Amir Shpilka. \nShort Bio:\n
 Deepanshu Kush is a fourth year PhD student in Computer Science at the Uni
 versity of Toronto\, where he is advised by Shubhangi Saraf. His research 
 interests are broadly in theoretical computer science and related areas of
  math with a focus on computational complexity theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1388
DTSTART;TZID=Asia/Kolkata:20240212T113000
DTEND;TZID=Asia/Kolkata:20240212T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1381
DTSTAMP:20240129T063348Z
SUMMARY:Competing Bandits in Non-Stationary Matching Markets
DESCRIPTION:Speaker: Prof. Avishek Ghosh (Indian Institute of Technology\, 
 Bombay (IITB))\n\nAbstract: \nUnderstanding complex dynamics of two-sided 
 online matching markets\, where the demand-side agents compete to match wi
 th the supply-side (arms)\, has recently received substantial interest. To
  that end\, in this paper\, we introduce the framework of decentralized tw
 o-sided matching market under non stationary (dynamic) environments. We ad
 here to the serial dictatorship setting\, where the demand-side agents hav
 e unknown and different preferences over the supply-side (arms)\, but the 
 arms have fixed and known preference over the agents. We propose and analy
 ze an asynchronous and decentralized learning algorithm\, namely Non-Stati
 onary Competing Bandits (NSCB)\, where the agents play  (restrictive) suc
 cessive elimination type learning algorithms to learn their preference ove
 r the arms. The complexity in understanding such a system stems from the f
 act that the competing bandits choose their actions in an asynchronous fas
 hion\, and the lower ranked agents only get to learn from a set of arms\, 
 not dominated by the higher ranked agents\, which leads to forced explorat
 ion. With carefully defined complexity parameters\, we characterize this f
 orced exploration and obtain sub-linear (logarithmic) regret of NSCB. Furt
 hermore\, we validate our theoretical findings via experiments.\nShort Bio
 :\nAvishek Ghosh (Ph.D UC Berkeley\, 2021) is an Assistant Professor at th
 e department of Systems and Control Engg. and The Centre for Machine Intel
 ligence and Data Science at IIT Bombay. Previously\, he was an HDSI (Data 
 Science) Post-doctoral fellow at the University of California\, San Diego.
  Prior to this\, he completed my PhD from the Electrical Engg. and Compute
 r Sciences (EECS) department of UC Berkeley\, advised by Prof. Kannan Ramc
 handran and Prof. Aditya Guntuboyina. His research interests are broadly i
 n Theoretical Machine Learning\, including Federated Learning and multi-ag
 ent Reinforcement/Bandit Learning. In particular\, Avishek is interested i
 n theoretically understanding challenges in multi-agent systems\, and comp
 etition/collaboration across agents. Before coming to Berkeley\, Avishek c
 ompleted his masters degree from Indian Institute of Science (IISc)\, Bang
 alore (at the Electrical Communication Engg. Dept) and prior Avishek compl
 eted his  bachelors degree from Jadavpur University\, in the dept. of Ele
 ctronics and Telecommunication Engineering.\n
URL:https://www.tcs.tifr.res.in/web/events/1381
DTSTART;TZID=Asia/Kolkata:20240213T160000
DTEND;TZID=Asia/Kolkata:20240213T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1389
DTSTAMP:20240209T090745Z
SUMMARY:Outlier Oblivious Robust Online Optimization
DESCRIPTION:Speaker: Dr. Adarsh Barik (National University of Singapore (NU
 S))\n\nAbstract: \nIn this talk\,  I will discuss a robust online convex 
 optimization framework\, where an adversary can introduce outliers by corr
 upting loss functions in an arbitrary number of rounds "k"\, unknown to th
 e learner. Our focus is on a novel setting allowing unbounded domains and 
 large gradients for the losses without relying on a Lipschitz assumption. 
 We introduce a non-convex (invex) robust loss to mitigate the effects of o
 utliers and develop a robust variant of the online gradient descent algori
 thm by leveraging our robust loss. We establish tight regret guarantees (u
 p to constants)\, both dynamic and static\,  with respect to the uncorrup
 ted rounds and conduct experiments to validate our theory. Furthermore\, w
 e present a unified analysis framework for developing online optimization 
 algorithms for non-convex (invex) losses\, utilizing it to provide regret 
 bounds for our robust loss\, which may be of independent interest.\nShort 
 Bio:\nAdarsh Barik is a postdoc at the Institute of Data Science at the Na
 tional University of Singapore. He did his PhD in Computer Science at Purd
 ue and his undergrad at IIT Madras before that. His research interests are
  broadly in Theoretical and computational aspect of Optimization\, Machine
  Learning\, Information Theory and High Dimensional Data Analytics.\n
URL:https://www.tcs.tifr.res.in/web/events/1389
DTSTART;TZID=Asia/Kolkata:20240215T111500
DTEND;TZID=Asia/Kolkata:20240215T121500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1395
DTSTAMP:20240215T090603Z
SUMMARY:The complexity of solving simple stochastic games
DESCRIPTION:Speaker: Pranshu Gaba (TIFR)\n\nAbstract: \nSimple stochastic g
 ames (SSG) are zero-sum games played by two players on a directed graph wi
 th a designated target vertex. The players take turns moving a token along
  the edges of the game graph. The objective of player 1 is to eventually r
 each the target vertex\, whereas the objective of player 2 is to never rea
 ch the target vertex. The SSG problem is to find the maximum probability w
 ith which player 1 wins the game. We will see that this problem is in NP 
 ∩ coNP.We will also see 3 more problems that are polynomial-time equival
 ent to SSG\, and thus also in NP ∩ coNP. Showing that any of these probl
 ems are in P would be a major breakthrough.You can read the following pape
 rs for more details.- The complexity of stochastic games\, Anne Condon (19
 92)https://www.sciencedirect.com/science/article/pii/089054019290048K- The
  Complexity of Solving Stochastic Games on Graphs\, Daniel Andersson & Pet
 er Bro Miltersen (2009) \nhttps://link.springer.com/chapter/10.1007/978-3
 -642-10631-6_13\n \n
URL:https://www.tcs.tifr.res.in/web/events/1395
DTSTART;TZID=Asia/Kolkata:20240216T173000
DTEND;TZID=Asia/Kolkata:20240216T183000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1400
DTSTAMP:20240222T081357Z
SUMMARY:Exponential Separation Between Powers of Regular and General Resolu
 tion Over Parities
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nPr
 oving super-polynomial lower bounds on the size of proofs of unsatisfiabil
 ity of Boolean formulas using resolution over parities\, is an outstanding
  problem that has received a lot of attention after its introduction by Ra
 z and Tzamaret. Very recently\, Efremenko\, Garlík and Itsykson proved th
 e first exponential lower bounds on the size of ResLin proofs that were ad
 ditionally restricted to be bottom-regular. We show that there are formul
 as for which such regular ResLin proofs of unsatisfiability continue to ha
 ve exponential size even though there exists short proofs of their unsatis
 fiability in ordinary\, non-regular resolution. This is the first super-po
 lynomial separation between the power of general ResLin and and that of re
 gular ResLin for any natural notion of regularity.    Our argument\, wh
 ile building upon the work of Efremenko et al\, uses additional ideas from
  the literature on lifting theorems.\nThis is joint work with Arkadev Cha
 ttopadhyay and Pavel Dvorak.\n
URL:https://www.tcs.tifr.res.in/web/events/1400
DTSTART;TZID=Asia/Kolkata:20240223T143000
DTEND;TZID=Asia/Kolkata:20240223T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1391
DTSTAMP:20240220T062209Z
SUMMARY:Bidding Games on Graphs : in Theory and in Practice
DESCRIPTION:Speaker: Dr. Suman Sadhukhan (University of Haifa)\n\nAbstract:
  \nIn a two-player zero-sum graph game\, the players move a token througho
 ut the game\, producing an infinite play\, which determines the winner of 
 the game. Bidding games are graph games in which in each turn\, a bidding 
 (auction) determines which player moves the token: the players have budget
 s\, and in each turn\, both players simultaneously submit the bids that do
  not exceed the available budgets. The higher bidder moves the token\, and
  pays the bid to the lower bidder (called Richman bidding).The standard so
 lution concept of interest in bidding games are threshold budgets: the nec
 essary and sufficient budget for winning the game.In this survey talk\, on
  the theoretical side\, we will explore discrete bidding games\, where the
  keyword discrete stands for the bids having a fixed granularity. We obtai
 n membership in NP \\cap coNP for solving parity bidding games with expone
 ntially succinct representation.This will be followed by our newly propose
 d application of bidding games to a decentralized synthesis problem for mu
 lti-objective decision making.Here\, synthesized policies express their sc
 heduling urgency via bids and a bounded budget guarantees long-run fairnes
 s. Moreover\, our proposed solution framework is modular\, in the sense th
 at if one objective changes\, we may still combine the policy for the othe
 r objective without having the need to recompute it from scratch.If time p
 ermits\, we will also walk through the theoretical development of poorman 
 counter-part of discrete bidding games\, which we study for the first time
 \, where instead of handing over the winning bid to the lower bidder\, the
  winner of a bid pays to a bank.These works have been in collaboration wit
 h Guy Avni\, Kaushik Mallik\, Tobias Meggendorfer\, Josef Tkadlec\, and Đ
 orđe Žikelić.\nShort Bio:\nSuman Sadhukhan is currently a postdoctoral 
 researcher at the University of Haifa. He obtained his PhD in 2022 from In
 ria Rennes where he was advised by Nathalie Bertrand\, Nicolas Markey and 
 Ocan Sankur. He is interested in\, but not restricted to\, Games on Graphs
 \, studying different game theoretic models from formal verification and r
 eactive synthesis viewpoint. Prior to his PhD training\, he was a student 
 at Chennai Mathematical Institute where he studied Theoretical Computer Sc
 ience and Mathematics.\n
URL:https://www.tcs.tifr.res.in/web/events/1391
DTSTART;TZID=Asia/Kolkata:20240227T160000
DTEND;TZID=Asia/Kolkata:20240227T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1397
DTSTAMP:20240228T090542Z
SUMMARY:Towards Robust and Reliable Machine Learning: Adversaries and Funda
 mental Limits
DESCRIPTION:Speaker: Arjun Bhagoji (University of Chicago)\n\nAbstract: \nW
 hile ML-based AI systems are increasingly deployed in safety-critical sett
 ings\, they continue to remain unreliable under adverse conditions that vi
 olate underlying statistical assumptions. In my work\, I aim to (i) unders
 tand the conditions under which a lack of reliability can occur and (ii) r
 eason rigorously about the limits of robustness\, during both training and
  test phases.In the first part of the talk\, I demonstrate the existence o
 f strong but stealthy training-time attacks on federated learning\, a rece
 nt paradigm in distributed learning. I show how a small number of compromi
 sed agents can modify model parameters via optimized updates to ensure des
 ired data is misclassified by the global model\, while bypassing custom de
 tection methods. Experimentally\, this model poisoning attack leads to a l
 ack of reliable prediction on standard datasets.Test-time attacks via adve
 rsarial examples\, i.e. imperceptible perturbations to test inputs\, have 
 sparked an attack-defense arms race. In the second part of the talk\, I st
 ep away from this arms race to provide model-agnostic fundamental limits o
 n the loss under adversarial input perturbations. The robust loss is shown
  to be lower bounded by the optimal transport cost between class-wise dist
 ributions using an appropriate adversarial point-wise cost\, the latter of
  which can be efficiently computed via a linear program for empirical dist
 ributions of interest.To conclude\, I will discuss my ongoing efforts and 
 future vision towards building continuously reliable and accessible ML sys
 tems by accounting for novel attack vectors and new ML paradigms such as g
 enerative AI\, as well as developing algorithmic tools to improve performa
 nce in data-scarce regimes.\nShort Bio:\nArjun Bhagoji is a Research Scien
 tist in the Department of Computer Science at the University of Chicago. H
 e obtained his Ph.D. in Electrical and Computer Engineering from Princeton
  University\, where he was advised by Prateek Mittal. Before that\, he rec
 eived his Dual Degree (B.Tech+M.Tech) in Electrical Engineering at IIT Mad
 ras\, where he was advised by Andrew Thangaraj and Pradeep Sarvepalli. Arj
 un's research has been recognized with a Spotlight at the NeurIPS 2023 con
 ference\, the Siemens FutureMakers Fellowship in Machine Learning (2018-20
 19) and the 2018 SEAS Award for Excellence at Princeton University. He was
  a 2021 UChicago Rising Star in Data Science\, a finalist for the 2020 Bed
 e Liu Best Dissertation Award in Princeton's ECE Department and a finalist
  for the 2017 Bell Labs Prize.\n
URL:https://www.tcs.tifr.res.in/web/events/1397
DTSTART;TZID=Asia/Kolkata:20240229T113000
DTEND;TZID=Asia/Kolkata:20240229T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1403
DTSTAMP:20240229T085137Z
SUMMARY:Proofs from X
DESCRIPTION:Speaker: Sahasranand K R (TIFR)\n\nAbstract: \nWe shall endeavo
 ur to provide simple and memorable proofs for some mathematical trivia.\n
URL:https://www.tcs.tifr.res.in/web/events/1403
DTSTART;TZID=Asia/Kolkata:20240301T143000
DTEND;TZID=Asia/Kolkata:20240301T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1382
DTSTAMP:20240228T090601Z
SUMMARY:Verification of Concurrent Programs under Release Acquire
DESCRIPTION:Speaker: Krishna S. (Indian Institute of Technology\, Bombay)\n
 \nAbstract: \nThis is an overview of some recent work on the verification 
 of concurrent programs. Traditionally concurrent programs are interpreted 
 under sequential consistency (SC). Even though SC is very intuitive and ea
 sy to use\, modern multiprocessors  do not employ SC for performance reas
 ons\, and instead use so called "weak memory models".  Some of the well k
 nown weak memory  models in vogue are  Intel x-86\, IBM POWER and ARM. 
  Weak memory features are also incorporated in the development of modern 
 programming languages  such as C11 and Java. This talk is on the verifica
 tion of concurrent programs under the release acquire (RA) semantics\, wit
 h the main focus being on decidability and complexity questions.\nShort Bi
 o:\nKrishna is a faculty member in the department of computer science and 
 engineering at IIT Bombay. Her areas of research are automata theory\, log
 ics\, and their applications to the verification of quantitative as well a
 s distributed/concurrent  systems.\n
URL:https://www.tcs.tifr.res.in/web/events/1382
DTSTART;TZID=Asia/Kolkata:20240305T160000
DTEND;TZID=Asia/Kolkata:20240305T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1404
DTSTAMP:20240307T103500Z
SUMMARY:A superpolynomial lower bound against weighted homogeneous formulas
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nOn the path to 
 proving lower bounds against general arithmetic/algebraic models of comput
 ation\, a longstanding open problem is to construct explicit polynomials t
 hat are superpolynomially hard for arithmetic formulas. Even for the poten
 tially weaker model of homogeneous formulas\, we do not have such strong l
 ower bounds. Recently\, Fournier\, Limaye\, Srinivasan and Tavenas gave a 
 superpolynomial lower bound against a related model of computation called 
 weighted homogeneous formulas\, thus getting us a little (or a lot?) close
 r to homogeneous formula lower bounds. The proof goes via a relatively sim
 ple application of the probabilistic method. We will try and understand th
 is proof. There are no prerequisites\, besides the vague notion of mathema
 tical maturity.\n
URL:https://www.tcs.tifr.res.in/web/events/1404
DTSTART;TZID=Asia/Kolkata:20240308T143000
DTEND;TZID=Asia/Kolkata:20240308T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1393
DTSTAMP:20240228T090617Z
SUMMARY:Best of Both Worlds in Fair Division
DESCRIPTION:Speaker: Rohit Vaish (Indian Institute of Technology Delhi)\n\n
 Abstract: \nEnsuring fairness is a fundamental aspect of human nature. In 
 times when an increasing amount of decision-making is being handed over to
  automated systems\, it is more important than ever to provide solutions w
 ith provable\, mathematically rigorous guarantees. The area of fair divisi
 on provides a formal theoretical framework to reason about such questions 
 in the context of resource allocation.\nThis talk will focus on the fair a
 llocation of indivisible resources\, which arises in real-world settings s
 uch as inheritance division and university course allocation. Traditional 
 approaches to this problem involve either randomized allocations that are 
 fair in expectation or deterministic allocations that are approximately fa
 ir. I will discuss an algorithmic framework that unifies randomization and
  approximation. Specifically\, I will present an algorithm for finding a r
 andomized allocation of indivisible goods that is ex-ante envy-free and ex
 -post envy-free up to one good. I will also touch upon some open problems 
 and potential avenues for future research.\nBased on joint work with Haris
  Aziz (UNSW Sydney)\, Rupert Freeman (University of Virginia)\, and Nisarg
  Shah (University of Toronto). https://pubsonline.informs.org/doi/full/10.
 1287/opre.2022.2432\nShort Bio:\nRohit Vaish is an Assistant Professor in 
 the Department of Computer Science and Engineering and an associate facult
 y member at the Yardi School of Artificial Intelligence\, both located at 
 IIT Delhi. Previously\, he was a postdoctoral researcher at TIFR and Renss
 elaer Polytechnic Institute. Before that\, he completed his PhD from IISc.
  Rohit's area of research is computational social choice. This field focus
 es on studying collective decision-making problems from a computational pe
 rspective. More generally\, he enjoys working on problems at the intersect
 ion of economics and computer science.\n
URL:https://www.tcs.tifr.res.in/web/events/1393
DTSTART;TZID=Asia/Kolkata:20240312T143000
DTEND;TZID=Asia/Kolkata:20240312T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1405
DTSTAMP:20240315T092242Z
SUMMARY:Fast multivariate multipoint evaluation
DESCRIPTION:Speaker: Shanthanu  Suresh Rai (TIFR)\n\nAbstract: \nProblem: W
 e are given a multivariate polynomial f(X_0\, X_1\, ...\, X_{m-1}) with co
 efficients from F_p and individual degrees atmost (d-1). For N evaluations
  points a_1\, a_2\, ...\, a_N\, compute f(a_i) for all i in [1\, N]We will
  first consider the simpler univariate version of this problem (evaluate f
 (X) at N points). Next\, we will discuss the algorithm for the general mul
 tivariate version by Kedlaya and Umans.\nReferences:- https://www.science
 direct.com/science/article/pii/S0022000074800292- https://epubs.siam.org/
 doi/10.1137/08073408X\n
URL:https://www.tcs.tifr.res.in/web/events/1405
DTSTART;TZID=Asia/Kolkata:20240315T143000
DTEND;TZID=Asia/Kolkata:20240315T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1410
DTSTAMP:20240322T081707Z
SUMMARY:On the robust hypothesis testing problem
DESCRIPTION:Speaker: Eeshan Modak (TIFR)\n\nAbstract: \nConsider the follow
 ing problem: Given a set of probability distributions (p_1\,p_2) and a sam
 ple access to an unknown target distribution p\, find which hypothesis (p_
 1 or p_2) is closer to p in total variation (TV). In general this is not p
 ossible. However\, we can output a p_i (from p_1 or p_2) such that TV(p_i\
 ,p) <= \\beta OPT + \\epsilon. Here OPT is the TV between p and the best c
 andidate in our set. We will show a simple test for which \\beta = 3 (whic
 h is in fact optimal). Time permitting\, we will also see that if we are a
 llowed to output a distribution not from the set (p_1\, p_2)\, then we can
  get \\beta = 2.\n
URL:https://www.tcs.tifr.res.in/web/events/1410
DTSTART;TZID=Asia/Kolkata:20240322T143000
DTEND;TZID=Asia/Kolkata:20240322T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1406
DTSTAMP:20240321T050025Z
SUMMARY:Demystifying the border of algebraic models
DESCRIPTION:Speaker: Nitin Saxena (IIT Kanpur)\n\nAbstract: \nBorder (or ap
 proximative) complexity of polynomials plays an integral role in GCT appro
 ach to P!=NP. This raises an important open question: can a border circuit
  be *efficiently* debordered (i.e. convert from approximative to exact)? O
 r\, could the approximation involve exponential-precision which may not be
  efficiently simulable? Circuits of depth 3 or 4\, are a good testing grou
 nd for this question.      Kumar (ToCT'20) proved the universal power
  of the border of top-fanin-2 depth-3 circuits. We recently solved some of
  the related open questions. In this talk we will outline our result:Borde
 r of bounded-top-fanin depth-3 circuits is relatively easy-- it can be com
 puted by a polynomial-size algebraic branching program (ABP). Our de-borde
 ring paradigm has many applications\, especially in identity testing\, low
 er bounds\, and factorization.Based on the works with Prateek Dwivedi & Pr
 anjal Dutta (CCC 2021) + (FOCS 2021\, invited to SICOMP) + (FOCS 2022) + (
 STOC 2024). [https://www.cse.iitk.ac.in/users/nitin/research.html]\nShort 
 Bio:\nNitin pursued his education at IIT Kanpur and completed his PhD ther
 e. He undertook research stints at Princeton University and the National U
 niversity of Singapore before joining CWI Amsterdam and later the Universi
 ty of Bonn. Currently\, he holds a professorship at IIT Kanpur and serves 
 as the N.Rama.Rao Chair\, alongside adjunct faculty roles elsewhere. Notab
 ly\, he spearheads the "Center for Developing Intelligent Systems" to tack
 le governance challenges at scale. In the realm of algebraic complexity\, 
 Nitin has made significant strides\, addressing prominent open problems th
 rough co-authored papers and pioneering algorithmic-algebraic techniques. 
 Active within the academic community\, Nitin engages in various committees
  and policy-making endeavors. Recognized for his contributions\, he has re
 ceived numerous accolades\, including the Gödel Prize\, Fulkerson Prize\,
  and Shanti Swarup Bhatnagar Prize.\n
URL:https://www.tcs.tifr.res.in/web/events/1406
DTSTART;TZID=Asia/Kolkata:20240323T160000
DTEND;TZID=Asia/Kolkata:20240323T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1402
DTSTAMP:20240315T044005Z
SUMMARY:Stochastic Gradient Descent using Zero-Order Estimators with Reduce
 d Estimation Bias
DESCRIPTION:Speaker: Shalabh Bhatnagar (Indian Institute of Science\, Banga
 lore)\n\nAbstract: \nWe present a new family of generalized simultaneous p
 erturbation stochastic gradient estimators that estimate the gradient of a
 n objective function using noisy function measurements\, but where the num
 ber of function measurements and the form of the gradient estimator is gui
 ded by the desired estimator bias. Estimators with more function measureme
 nts are seen to result in lower bias. We sketch an asymptotic convergence 
 argument under a constant gradient estimation parameter to the attractor o
 f a limiting differential inclusion as well as provide a finite time bound
  on the mean-squared error under certain conditions. \nShort Bio:\nShalab
 h Bhatnagar received a B.Sc(Hons) in Physics (Delhi University\, 1988)\, 
 followed by a Master's and PhD in Electrical Engineering from IISc (1992/9
 7). He was a Research Associate at the University of Maryland\, College P
 ark (1997-2000) and the Vrije Universiteit\, Amsterdam (2000-01). He is w
 ith the CSA Department of IISc since December 2001 and is currently a Sen
 ior Professor. His interests are in stochastic approximation algorithms\, 
 reinforcement learning and stochastic optimization. He is a Fellow of all 
 major science and engineering academies in India and is a J.C.Bose Nationa
 l Fellow.\n
URL:https://www.tcs.tifr.res.in/web/events/1402
DTSTART;TZID=Asia/Kolkata:20240402T160000
DTEND;TZID=Asia/Kolkata:20240402T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1412
DTSTAMP:20240403T092106Z
SUMMARY:The complexity of contracts [Roughgarden et. al.]
DESCRIPTION:Speaker: Soumyajit Pyne (TIFR)\n\nAbstract: \nThe paper focuses
  on principal-agent settings with succinctly described outcome space (expo
 nentially large). The goal of the principal is to design a contract that m
 aximizes its expected payoff. The authors show that for n > 2 actions this
  problem turns out to be NP-hard. For settings with a constant number of a
 ctions\, the authors present a fully polynomial-time approximation scheme 
 (FPTAS) for the separation oracle of the dual of the problem of minimizing
  the principal's payment to the agent\, and use this subroutine to efficie
 ntly compute a delta-incentive-compatible (delta-IC) contract whose expect
 ed payoff matches or surpasses that of the optimal IC contract.With an arb
 itrary number of actions\, the authors prove that the problem is hard to a
 pproximate within any constant c. This inapproximability result holds even
  for delta-IC contracts where delta is a sufficiently rapidly-decaying fun
 ction of c. On the positive side\, the authors show that simple linear del
 ta-IC contracts with constant delta are sufficient to achieve a constant-f
 actor approximation of the "first-best" (full-welfare-extracting) solution
 \, and that such a contract can be computed in polynomial time.\nHere is t
 he link to the paper : https://arxiv.org/abs/2002.12034\n
URL:https://www.tcs.tifr.res.in/web/events/1412
DTSTART;TZID=Asia/Kolkata:20240405T160000
DTEND;TZID=Asia/Kolkata:20240405T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1394
DTSTAMP:20240403T042706Z
SUMMARY:Capacitated Facility Location with Outliers
DESCRIPTION:Speaker: Naveen Garg (Indian Institute of Technology Delhi)\n\n
 Abstract: \nIn this talk I will present a simple local search algorithm fo
 r capacitated facility location when facility costs are uniform. Our algor
 ithm is a 3.732-approximation and improves the 4-approximation of Kao. \nI
 n the second part of the talk\, I will consider the setting when we are pe
 rmitted not to serve L clients (outliers). We extend the local search alg
 orithm to obtain the first constant factor approximation for this problem.
  Our local search algorithm requires only 2 operations and is a 6.372-appr
 oximation.\nShort Bio:\nNaveen Garg is the Usha Hasteer Professor of Compu
 ter Science at the Indian Institute of Technology Delhi. He did his B.Tech
 . and Ph.D. in Computer Science from IIT Delhi\, was a postdoctoral resear
 cher at the Max-Planck-Institut fur Informatik\, Germany and since 1998 he
  has been a faculty member at IIT Delhi. He is currently on a sabbatical a
 t the University of Warwick\, UK as a Royal Society Wolfson visiting profe
 ssor.\nNaveen's contributions are primarily in the design and analysis of 
 approximation algorithms for NP-hard combinatorial optimization problems a
 rising in network design\, scheduling\, routing\, facility location etc. H
 e is a Fellow of Indian Academy of Science\, and the Indian National Acade
 my of Engineering and was awarded the SS Bhatnagar award for Mathematical 
 Sciences in 2016.\n
URL:https://www.tcs.tifr.res.in/web/events/1394
DTSTART;TZID=Asia/Kolkata:20240409T160000
DTEND;TZID=Asia/Kolkata:20240409T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1413
DTSTAMP:20250715T083615Z
SUMMARY:An introduction to stabilizer codes
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR)\n\nAbstract: \nQuantum error c
 orrection has certain challenges that aren't present in the classical case
 : phase flips in addition to bit flips\, the no cloning theorem and more. 
 I'll talk about stabilizer codes\, including surface codes\, which can det
 ect and correct these errors.Basic knowledge of qubits and gates would be 
 handy in following the talk.\n
URL:https://www.tcs.tifr.res.in/web/events/1413
DTSTART;TZID=Asia/Kolkata:20240412T143000
DTEND;TZID=Asia/Kolkata:20240412T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1398
DTSTAMP:20240416T043235Z
SUMMARY:NP-hardness of testing equivalence to sparse polynomials
DESCRIPTION:Speaker: Chandan Saha (Indian Institute of Science\, Bangalore)
 \n\nAbstract: \nThe Polynomial Equivalence (PE) problem asks to check if t
 wo given multivariate polynomials are equivalent. Polynomials f(x) and g(x
 ) are equivalent if there is an invertible matrix A such that f = g(Ax). E
 quivalent polynomials represent the same function up to a change in the co
 ordinate system. Much is unknown about the exact complexity of PE\, which 
 is an algebraic analog of the graph isomorphism problem. \nA natural vari
 ant of PE is the equivalence testing (ET) problem. The ET problem for a cl
 ass C of polynomials asks to decide if a given f is equivalent to some g i
 n C. Efficient ET algorithms are known for several natural classes of poly
 nomials.\nIn the talk\, we will discuss the complexity of deciding if a gi
 ven polynomial f is equivalent to some s-sparse polynomial\, where the par
 ameter s is also given. A polynomial is s-sparse if it has at most s monom
 ials. We will show that this problem is NP-hard. Moreover\, it is also NP-
 hard to approximate (within a "small" factor) the smallest s such that f i
 s equivalent to some s-sparse polynomial. If time permits\, we will also d
 iscuss an NP-hardness result for testing equivalence to low-support polyno
 mials. \nBased on joint work with Omkar Baraskar\, Agrim Dewan\, and Pulk
 it Sinha.\nShort Bio:\nChandan Saha is a faculty member in the Department 
 of Computer Science and Automation at the Indian Institute of Science (IIS
 c). He did his PhD and MTech at IIT Kanpur and BE at Jadavpur University. 
 He was a postdoctoral fellow at the Max Planck Institute for Informatics b
 efore joining IISc in 2012. His research is primarily on problems in algeb
 raic complexity theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1398
DTSTART;TZID=Asia/Kolkata:20240416T160000
DTEND;TZID=Asia/Kolkata:20240416T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1414
DTSTAMP:20240418T101926Z
SUMMARY:Online Convex Optimization with Switching Cost and Delayed Gradient
 s
DESCRIPTION:Speaker: Pranab Panda (TIFR)\n\nAbstract: \nThis paper focuses 
 on Online Convex Optimization (OCO) problem with linear and quadratic swit
 ching costs and by the help of an online algorithm OMGD(Online Multiple Gr
 adient Descent) for a class of L smooth and μ strongly convex functions\,
  in limited information setting (where at time t we choose x_t without kno
 wing f_t and our objective is to minimise f(x) + S(x_t-1\, x_t) summed ove
 r t. S(.\,.) is the switching cost)\, we can achieve a competitive ratio o
 f at most 4(L + 5) + 16(L + 5)/μ for quadratic switching cost.Online conv
 ex optimization captures many crucial real world problems like server mana
 gement in data centres\, etc. We will also try to look at how the performa
 nce of online algorithms changes even when the switching cost changes from
  quadratic to linear.\nPaper: https://arxiv.org/abs/2310.11880\n
URL:https://www.tcs.tifr.res.in/web/events/1414
DTSTART;TZID=Asia/Kolkata:20240419T160000
DTEND;TZID=Asia/Kolkata:20240419T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1399
DTSTAMP:20240405T070007Z
SUMMARY:Approximate Nearest Neighbor Search algorithms for web-scale search
  and recommendation
DESCRIPTION:Speaker: Ravishankar Krishnaswamy (Microsoft Research Lab – I
 ndia)\n\nAbstract: \n\nWeb-scale search and recommendation scenarios incre
 asingly use Approximate Nearest Neighbor Search (ANNS) algorithms to index
  and retrieve objects based on the similarity of their learnt representati
 ons in a geometric space. Since these scenarios often span billions or tri
 llions of objects\, efficient and scalable ANNS algorithms are critical to
  making these systems practical.\nIn this talk we discuss some recent empi
 rical progress on this problem. Specifically\, we present DiskANN\, an ANN
 S algorithm that can index a billion points and serve queries at latencies
  of few milliseconds on a single commodity machine. This represents an ord
 er of magnitude more points indexed per machine than previous work.  We w
 ill also discuss some fundamental open problems in this space in the latte
 r half of the talk.\nBased on joint works with Harsha Simhadri\, Sujas J S
 ubramanya\, Aditi Singh\, Rohan Kadekodi\, Devvrit\, Shikhar Jaiswal\, Mag
 dalen Dobson\, Siddharth Gollapudi\, Neel Karia\, Varun Sivashankar\, and 
 Varun Suriyanarayana.\nShort Bio:\nHe is a principal researcher at Microso
 ft Research India. His PhD was completed at Carnegie Mellon University in 
 2012. From 2012-2014\, a Simons Postdoctoral Fellowship was held by him at
  the CS Department in Princeton University. Long\, long ago\, he was an un
 dergrad at IIT Madras. Broad interest in basic problems in algorithms and 
 optimization characterizes his work. Lately\, work on the design of very l
 arge-scale (billions of vectors) approximate nearest neighbor search (ANNS
 ) has been undertaken as part of the DiskANN project. Also\, he spends his
  time thinking about basic problems in online and approximation algorithms
 \, especially for graph-theoretic and clustering problems.\n
URL:https://www.tcs.tifr.res.in/web/events/1399
DTSTART;TZID=Asia/Kolkata:20240423T160000
DTEND;TZID=Asia/Kolkata:20240423T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1415
DTSTAMP:20240423T101531Z
SUMMARY:On the Nystrom Approximation for Preconditioning in Kernel Machines
DESCRIPTION:Speaker: Parthe Pandit (IIT Bombay)\n\nAbstract: \nKernel metho
 ds are a popular class of nonlinear predictive models in machine learning.
  Scalable algorithms for learning kernel models need to be iterative in na
 ture\, but convergence can be slow due to poor conditioning. Spectral prec
 onditioning is an important tool to speed-up the convergence of such itera
 tive algorithms for training kernel models. However computing and storing 
 a spectral preconditioner can be expensive which can lead to large computa
 tional and storage overheads\, precluding the application of kernel method
 s to problems with large datasets. A Nystrom approximation of the spectral
  preconditioner is often cheaper to compute and store\, and has demonstrat
 ed success in practical applications. In this paper we analyze the trade-o
 ffs of using such an approximated preconditioner. Specifically\, we show t
 hat a sample of logarithmic size (as a function of the size of the dataset
 ) enables the Nystrom-based approximated preconditioner to accelerate grad
 ient descent nearly as well as the exact preconditioner\, while also reduc
 ing the computational and storage overheads. This is joint work with Amir
 hesam Abedsoltan\, Luis Rademacher\, and Mikhail Belkin.\n
URL:https://www.tcs.tifr.res.in/web/events/1415
DTSTART;TZID=Asia/Kolkata:20240424T130000
DTEND;TZID=Asia/Kolkata:20240424T140000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1416
DTSTAMP:20240425T085118Z
SUMMARY:Quantifier Elimination in Presburger Arithmetic
DESCRIPTION:Speaker: Koduri Choudary (TIFR)\n\nAbstract: \nPresburger Arith
 metic is the sub-category of First Order Logic\, which deals with quantifi
 cation over Integers\, with addition\, order relation\, and multiplication
  and divisibility by constants. Our goal is to decide the truth value of s
 entence of Presburger Arithmetic by eliminating the quantifiers.Source: De
 rek C. Oppen\, A $2^{2^{2^{pn}}}$ Upper Bound on the Complexity of Presbur
 ger Arithmetic\, 323-332\, Journal of Computer and System Sciences\, 1978.
 https://www.sciencedirect.com/science/article/pii/0022000078900211\n
URL:https://www.tcs.tifr.res.in/web/events/1416
DTSTART;TZID=Asia/Kolkata:20240426T143000
DTEND;TZID=Asia/Kolkata:20240426T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1401
DTSTAMP:20240410T090637Z
SUMMARY:Trading determinism for noncommutativity in Singularity testing
DESCRIPTION:Speaker: Partha Mukhopadhyay (Chennai Mathematical Institute)\n
 \nAbstract: \nFinding an efficient deterministic algorithm for symbolic de
 terminant identity testing (SDIT) is one of the most important problems in
  computational complexity and very little is known about it. Around 2016\,
  two independent research groups solved the noncommutative version of the 
 problem in deterministic polynomial time (Garg-Gurvits-Oliveira-Wigderson 
 2016\, Ivanyos-Qiao-Subrahmanyam 2017) using very different techniques. In
  this talk\, we will discuss a different algorithm for this problem based 
 on noncommutative polynomial identity testing. Then I will briefly sketch 
 how this new technique is lifted to approach the partially commutative var
 iant of the  SDIT and related problems efficiently.  The talk is based o
 n joint work with V. Arvind\, and Abhranil Chatterjee.\nShort Bio:\nPartha
  Mukhopadhyay obtained his PhD from The Institute of Mathematical Sciences
  (IMSc\, 2009)\, and then he was a postdoctoral fellow at the Israel Insti
 tute of Technology. (Technion\, 2010). Since then\, he is a faculty member
  at Chennai Mathematical Institute (CMI). His research interest is mainly 
 in the design of algorithms for problems which have algebraic flavour. Out
 side academics\, he enjoys long distance running\, table tennis\, and pain
 ting.  \n
URL:https://www.tcs.tifr.res.in/web/events/1401
DTSTART;TZID=Asia/Kolkata:20240430T160000
DTEND;TZID=Asia/Kolkata:20240430T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1420
DTSTAMP:20240502T093307Z
SUMMARY:A generalization of the Coupon Collector Problem
DESCRIPTION:Speaker: Jainam Khakhra (TIFR)\n\nAbstract: \nThe Coupon Collec
 tor is a well known problem in Probability Theory and has given rise to se
 veral interesting larger problems and generalizations. In this talk\, we d
 iscuss the Coupon Collector Problem and a specific generalization of it by
  introducing the notion of a Super Coupon which is an s-sized subset of a 
 universe of n coupons. If time permits we discuss this in the context of R
 andom Walks on Graphs. The talk will be based on the paper\, "On a General
 ization of the Coupon Collector Problem" by Siva Athreya\, Satyaki Mukherj
 ee and Soumendu Sundar Mukherjee.\nLink to paper: https://arxiv.org/pdf/2
 304.01145\n
URL:https://www.tcs.tifr.res.in/web/events/1420
DTSTART;TZID=Asia/Kolkata:20240503T143000
DTEND;TZID=Asia/Kolkata:20240503T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1396
DTSTAMP:20240501T045410Z
SUMMARY:Unlikely Friendships: Fruitful Interplay of Mathematical Structures
  in Cryptography
DESCRIPTION:Speaker: Shweta Agrawal (Indian Institute of Technology\, Madra
 s)\n\nAbstract: \nThe security of cryptographic protocols is based on the 
 conjectured intractability of some mathematical problem\, typically a sin
 gle problem. However\, in some cases\, novel constructions emerge out of 
 the surprising interplay of seemingly disparate mathematical structures a
 nd conjectured hard problems on these. Though unusual\, this cooperation b
 etween assumptions\, when it happens\, can lead to progress on important o
 pen problems. This sometimes paves the way for subsequent improvements\, w
 hich may even eliminate the multiplicity and reduce security to a single a
 ssumption.\nIn this talk\, I will give examples from recent work that have
  benefited from this interplay\, leveraging diverse mathematical structur
 es and assumptions in a way that yields more than a "sum of parts"\, and l
 eads to surprising progress in longstanding problems.\nShort Bio:\nDr. Shw
 eta Agrawal is a professor at the Computer Science and Engineering departm
 ent\, at the Indian Institute of Technology\, Madras. She earned her PhD a
 t the University of Texas at Austin\, and did her postdoctoral work at the
  University of California\, Los Angeles. Her area of research is cryptogra
 phy with a focus on post quantum cryptography. She has won multiple awards
  and honours such as the Swarnajayanti award\, the ACM India award for Out
 standing Contributions to Computing by a Woman\, a best paper award at Eur
 ocrypt\, Google India faculty award\, BY award for excellence in research 
 and teaching\, invited speaker at prestigious conferences like Asiacrypt a
 nd "Women in Mathematics" and program co-chair for the flagship conference
  Asiacrypt.\n
URL:https://www.tcs.tifr.res.in/web/events/1396
DTSTART;TZID=Asia/Kolkata:20240507T160000
DTEND;TZID=Asia/Kolkata:20240507T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1422
DTSTAMP:20240509T035847Z
SUMMARY:Online Age-of-Information Scheduling
DESCRIPTION:Speaker: Kumar Saurav (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1422
DTSTART;TZID=Asia/Kolkata:20240509T110000
DTEND;TZID=Asia/Kolkata:20240509T130000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1423
DTSTAMP:20240509T082219Z
SUMMARY:Resolution is NP hard to automate
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nA 
 proof system P is called automatizable if there is an algorithm A that\, g
 iven input a statement phi\, runs in time poly(s) and outputs a P-proof of
  phi of size at most poly(s)\, where s is the size of the shortest P-proof
  of phi. It had been a long-standing open problem to determine if resoluti
 on is automatizable. In a breakthrough result\, Atserias and Muller showed
  that automating resolution is NP hard. They construct a polynomial time c
 omputable transformation A that\, on input a CNF phi\, outputs an unsatisf
 iable CNF A(phi) such that:(i) If phi is satisfiable\, A(phi) has polynomi
 al sized resolution refutations(ii) If phi is not satisfiable\, A(phi) doe
 s not have any subexponential sized resolution refutationWe shall describe
  this construction.\n
URL:https://www.tcs.tifr.res.in/web/events/1423
DTSTART;TZID=Asia/Kolkata:20240510T160000
DTEND;TZID=Asia/Kolkata:20240510T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1411
DTSTAMP:20240502T053036Z
SUMMARY:Navigating the Transformative Landscape of Generative AI: Some Stat
 istical and Ethical Perspectives of the Large Language Models
DESCRIPTION:Speaker: Swagatam Das (Indian Statistical Institute (ISI)\, Kol
 kata)\n\nAbstract: \nIn this talk\, we embark on a journey through the dyn
 amic landscape of Generative AI\, delving into both statistical intricacie
 s and ethical considerations surrounding Large Language Models (LLMs). We 
 dissect the statistical modeling techniques employed in generative models\
 , shedding light on the emergence of GAN and diffusion models and the pivo
 tal role transformers play in sequential data.  Amidst the transformative
  potential of these models\, we confront the pressing issue of bias and et
 hical concerns\, exploring avenues for mitigating algorithmic biases and p
 romoting ethical AI practices. The talk will finally touch upon some of th
 e open problems that exist in this field. \nShort Bio:\nSwagatam Das\, a 
 Professor at the Indian Statistical Institute\, Kolkata\, earned his B.E.\
 , M.E.\, and Ph.D. degrees from Jadavpur University. Formerly Deputy Direc
 tor at TCG CREST\, his research spans deep learning and non-convex optimiz
 ation\, with over 400 publications. He co-founded Swarm and Evolutionary C
 omputation and serves as Associate Editor for prestigious journals. With 3
 2\,000+ Google Scholar citations and an H-index of 84\, he's renowned inte
 rnationally\, participating in top conferences like NeurIPS and receiving 
 accolades such as the 2012 Young Engineer Award and the 2015 Thomson Reute
 rs Research Excellence India Citation Award.\n
URL:https://www.tcs.tifr.res.in/web/events/1411
DTSTART;TZID=Asia/Kolkata:20240514T110000
DTEND;TZID=Asia/Kolkata:20240514T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1426
DTSTAMP:20240516T083228Z
SUMMARY:The connection between circuit complexity and first-order logic
DESCRIPTION:Speaker: Pranshu Gaba (TIFR)\n\nAbstract: \nDescriptive complex
 ity is a branch of computational complexity where complexity classes are d
 escribed using forms of logic\, giving machine-independent characterizatio
 ns of the complexity classes. In this talk\, we look at an important resul
 t in descriptive complexity:[BIS88\, Theorem 8.1] A class of structures is
  in DLOGTIME-uniform AC0 if and only if the class is definable in first-or
 der logic with numerical predicates.Here\, DLOGTIME is the class of langua
 ges accepted by a deterministic random-access Turing machine in logarithmi
 c time.A language is said to be in DLOGTIME-uniform AC0 if it can be recog
 nized by a family of constant-depth\, polynomial-size circuits with AND an
 d OR gates\, where the circuits can be constructed by a DLOGTIME machine. 
 The proof involves showing that if a language is in DLOGTIME\, then it is 
 definable in first-order logic with numerical predicates.Reference:[BIS88]
  David A. Mix-Barrington\, Neil Immerman\, and Howard Straubing. 1990. On 
 uniformity within NC1. J. Comput. Syst. Sci. 41\, 3 (Dec. 1990)\, 274–30
 6. https://doi.org/10.1016/0022-0000(90)90022-D\n
URL:https://www.tcs.tifr.res.in/web/events/1426
DTSTART;TZID=Asia/Kolkata:20240517T113000
DTEND;TZID=Asia/Kolkata:20240517T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1428
DTSTAMP:20240522T041810Z
SUMMARY:Local Correction of Linear Functions over the Boolean Cube
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Paulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nSince the late 1980's it has bee
 n known that low-degree multivariate polynomials over finite fields form "
 locally correctible codes". In other words\, given oracle access to a func
 tion f:F^n -> F such there is a degree d polynomial P(X1...Xn) whose evalu
 ation agree with f on all but a tiny fraction of points\, and an arbitrary
  point b in F^n\, it is possible to determine P(b) with high probability 
 while querying f in a constant number of points (where the number of queri
 es depends on the degree d\, but not the number of variables n).Of course 
 this result doesn't work for infinite fields since then one has to define 
 a measure over F^n. But can one hope for a similar result for f:S^n \\to F
  for some finite subset S of F? In a previous work with Bafna and Srinivas
 an we had shown that any such local decoding result (over say the reals or
  rationals) would require roughly Omega-tilde(\\log n) queries (even when 
 d = 1).In this talk we describe a complementary result that shows that O-t
 ilde(\\log n) queries suffice in the linear (d=1) case when S = {0\,1} (ov
 er any field F\, and indeed any abelian group G). Working over sets like S
 ^n provides novel challenges due to the fact that the most handy tool in p
 revious works\, namely affine-invariance of the domain\, is no longer avai
 lable. Our local reconstruction algorithms rely centrally on the ability t
 o construct a small set of nearly balanced vectors in {-1\,1}^n whose span
  contains 1^n. Combined with a double dose of hypercontractivity this lead
 s to a local algorithm correcting up to 1/4  fraction of errors. Our fina
 l result gives a list-decoding algorithm correcting nearly 50% errors. Her
 e the key ingredient is the combinatorial bound on the list size which we 
 prove using a kitchen sink of techniques that show large lists must contai
 n many sparse polynomials and then ruling out such possibilities which inv
 olves case analysis depending on the group G.\nJoint work with Prashanth A
 mireddy\, Amik Raj Behera\, Manaswi Paraashar\, and Srikanth Srinivasan.\n
URL:https://www.tcs.tifr.res.in/web/events/1428
DTSTART;TZID=Asia/Kolkata:20240528T140000
DTEND;TZID=Asia/Kolkata:20240528T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1427
DTSTAMP:20240521T095005Z
SUMMARY:Learning in Large and Structured Environments: Algorithms\, Guarant
 ees and Applications
DESCRIPTION:Speaker: Sayak Chowdhury (Microsoft Research Lab\, India)\n\nAb
 stract: \n\nIn this talk\, I will present some of my work on designing and
  analyzing algorithms for learning in large and structured environments\, 
 where the state and action spaces are huge or even infinite. I will focus 
 on two main topics: (1) Bayesian optimization for hyperparameter tuning in
  large-scale machine learning models\, and (2) Policy optimization for lan
 guage models using human feedback. For the first topic\, I will introduce
  the Gaussian process optimization framework and design multi-armed-bandi
 t algorithms for hyperparameter optimization. I will show sublinear regre
 t bounds for the proposed algorithms that depend on the information comple
 xity of the objective function to be optimized. Along the way\, I will pr
 esent a self-normalized concentration inequality for vector-valued marting
 ales of arbitrary\, possibly infinite\, dimension\, and discuss some appli
 cations of this concentration bound. For the second topic\, I will talk a
 bout the effects of noisy preference data that can negatively impact lang
 uage model alignment. I will propose a robust loss function for language 
 model policy optimization in the presence of random preference flips. I w
 ill show that the proposed language model policy is provably tolerant to 
 noise and characterize its sub-optimality gap as a function of noise rate\
 , dimension of the policy parameter\, and sample size. I will also demons
 trate the empirical performance of the proposed policy on various tasks\, 
 such as dialogue generation and sentiment analysis. I will conclude with 
 some open problems and future directions of research in large scale machin
 e learning.\n \nShort Bio:\nSayak Ray Chowdhury is a postdoctoral researc
 her at Microsoft Research\, India. Prior to this he was a postdoctoral fel
 low at Boston University\, USA. He obtained his PhD from the Dept of ECE\,
  Indian Institute of Science\, where he was a recipient of Google PhD fell
 owship. His research interests include reinforcement learning\, Bayesian o
 ptimization\, multi-armed bandits and differential privacy. Recently\, he 
 has been working towards mathematical and empirical understandings of lang
 uage models. More details about his research can be found here: https://si
 tes.google.com/view/sayakraychowdhury/home\n \n
URL:https://www.tcs.tifr.res.in/web/events/1427
DTSTART;TZID=Asia/Kolkata:20240529T160000
DTEND;TZID=Asia/Kolkata:20240529T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1408
DTSTAMP:20240514T040141Z
SUMMARY:Knapsack: Connectedness\, Path\, and Shortest-Path
DESCRIPTION:Speaker: Palash Dey (Indian Institute of Technology\, Kharagpur
 )\n\nAbstract: \nWe study the Knapsack problem with graph-theoretic constr
 aints. That is\, there exists a graph structure on the input set of items 
 of Knapsack and the solution also needs to satisfy certain graph theoretic
  properties on top of the Knapsack constraints. In particular\, we study C
 onnected Knapsack where the solution must be a connected subset of items w
 hich has maximum value and satisfies the size constraint of the knapsack. 
 We show that this problem is strongly NP-complete even for graphs of maxim
 um degree four and NP-complete even for star graphs. On the other hand\, w
 e develop an algorithm running in time O(2^{tw log tw} · poly (n) min{s^2
 \, d^2}) where tw\, s\, d\, n are respectively treewidth of the graph\, th
 e size of the knapsack\, the target value of the knapsack\, and the number
  of items. We also exhibit a (1 − epsilon) factor approximation algorith
 m running in time O(2^{tw log tw} · poly (n\, 1/epsilon)) for every epsil
 on > 0. We show similar results for Path Knapsack and Shortest Path Knapsa
 ck\, where the solution must also induce a path and shortest path\, respec
 tively. Our results suggest that Connected Knapsack is computationally the
  hardest\, followed by Path Knapsack and then Shortest Path Knapsack.\nSho
 rt Bio:\nProf. Palash Dey is an Assistant Professor in the Department of C
 omputer Science and Engineering at the Indian Institute of Technology Khar
 agpur. Before joining IIT Kharagpur\, he spent around a year as a visiting
  post-doctoral fellow at the School of Technology and Computer Science (ST
 CS) at Tata Institute of Fundamental Research (TIFR) Mumbai. Before that\,
  he finished his PhD and Master of Engineering from the Department of Comp
 uter Science and Automation in 2017 and 2013\, respectively. He received t
 he INSPIRE Faculty Award in 2018 and the ACM India Best Dissertation Award
  in 2017. He has been a fellow of the West Bengal Academy of Science and T
 echnology\, Government of West Bengal\, India\, since 2022 and an INAE You
 ng Associate since 2023. He is an ACM India Eminent Speaker for 2024-26. H
 is research focuses on Algorithmic Game Theory and Parameterized Algorithm
 s.\n
URL:https://www.tcs.tifr.res.in/web/events/1408
DTSTART;TZID=Asia/Kolkata:20240604T160000
DTEND;TZID=Asia/Kolkata:20240604T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1425
DTSTAMP:20240527T102107Z
SUMMARY:Bridging the Theory and Practice of Cryptography
DESCRIPTION:Speaker: Ashrujit Ghoshal (Carnegie Mellon University)\n\nAbstr
 act: \nIn the current internet landscape\, cryptography plays a central r
 ole in securing communication. We rely on mathematical proofs to ensure s
 ecurity of the cryptographic systems that are deployed in practice. Howev
 er\, in many cases\, due to issues like efficiency constraints\, there is
  a gap between what these deployments need and what we can prove. In this
  talk\, I will describe how my research identifies these gaps and makes p
 rogress towards bridging these gaps using new theoretical insights and tec
 hniques from different areas of computer science like complexity theory\,
  algorithms\, combinatorics\, information theory\, etc.More concretely\, 
 my work contributes towards bridging these gaps in three different ways. F
 irst\, I provide exact security analyses of cryptographic systems that hav
 e been deployed at scale that did not have such analyses before. With the 
 exact analyses available\, practitioners can set parameters of the cryptog
 raphic system in a way that maximizes efficiency without sacrificing secur
 ity. Secondly\, I construct new cryptographic schemes that are better than
  existing schemes in terms of efficiency. This work helps make purely theo
 retical cryptographic notions practical. Finally\, my work incorporates ne
 wer perspectives into the framework of security proofs that captures a mor
 e complete picture of the real world. This is in contrast to prior work wh
 ere only certain adversarial resources were taken into account. A more com
 plete picture of adversarial resources often helps in setting parameters i
 n a way that increases efficiency of cryptographic systems.\nShort Bio: As
 hrujit Ghoshal is a postdoctoral fellow at Carnegie Mellon University. He
  received his PhD from the University of Washington in 2023. His research
  focuses on bridging the gap between the theory and practice of cryptogra
 phy by developing new theory that characterizes security and efficiency o
 f cryptographic systems as precisely as possible. In particular his work 
 has provided exact security analyses for cryptography that is widely used
  in practice e.g.\, standard hash functions like SHA-2 and SHA-3\, TLS\, 
 etc. His work has also made progress towards making theoretical cryptogra
 phic functionalities like private information retrieval more practical by
  giving new concretely efficient constructions. These works have led to m
 ultiple papers at the two top cryptography conferences- CRYPTO and EUROCR
 YPT.\n
URL:https://www.tcs.tifr.res.in/web/events/1425
DTSTART;TZID=Asia/Kolkata:20240605T160000
DTEND;TZID=Asia/Kolkata:20240605T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1421
DTSTAMP:20240521T095047Z
SUMMARY:Lower Bounds for Planar Arithmetic Circuits
DESCRIPTION:Speaker: Ramya C. (The Institute of Mathematical Sciences)\n\nA
 bstract: \nArithmetic circuits are a natural computational model for compu
 ting multivariate polynomials over a field. Planar arithmetic circuits are
  circuits whose underlying graph is planar. The size of a circuit  which 
 is the number of vertices in the underlying graph is a fundamental paramet
 er concerning circuits. In this talk\, we will prove  a superlinear lower
  bound on the size of planar arithmetic circuits computing an explicit bil
 inear form. More generally\, we will walk-through the algebraic complexity
  of bilinear forms. Furthermore\, Baur and Strassen(1983) showed that all 
 the first order partial derivatives of a polynomial can be simultaneously 
 computed with only a constant factor blow-up in size. We observe that an a
 nalogous statement does not hold in the case of planar circuits.\nThis tal
 k is based on joint work with Pratik Shastri(IMSc).\nShort Bio:\nRamya is 
 currently a faculty member in the Theoretical Computer Science group at th
 e Institute of Mathematical Sciences(IMSc)\, Chennai.Prior to this\, she w
 as a faculty member at the Chennai Mathematical Institute(CMI). Before joi
 ning CMI\, she was a postdoctoral fellow at  STCS\, TIFR\, Mumbai during 
 2019-2021.She obtained her PhD from IIT Madras in 2019. Her research is ce
 ntered around Computational Complexity Theory\, particularly problems with
  an algebraic flavor.\n
URL:https://www.tcs.tifr.res.in/web/events/1421
DTSTART;TZID=Asia/Kolkata:20240611T160000
DTEND;TZID=Asia/Kolkata:20240611T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1419
DTSTAMP:20240603T043420Z
SUMMARY:List decoding and Higher Order MDS codes
DESCRIPTION:Speaker: Manik Dhar (Massachusetts Institute of Technology)\n\n
 Abstract: \nA [n\,k] code C is a k-dimensional subspace in F_q^n. C is sai
 d to be MDS (maximal distance separable) if its hamming weight is n-k+1 wh
 ich is the largest possible by the singleton bound. It is also equivalent 
 to saying that every k minor of the generator matrix of C is invertible. T
 his can be rewritten as saying that any two subspaces formed by the column
 s of the generator matrix of C intersect as minimally as possible.\nBraken
 siek\, Gopi\, and Makam generalize this notion to introduce MDS(l) codes w
 here we ask that any l subspace formed by the columns of the generator mat
 rix of C intersect as minimally as possible. In a series of works\, they s
 how their new notion is equivalent to an alternative notion of higher-orde
 r MDS codes introduced by Roth related to list decoding. In particular\, t
 he parity check matrix of code being MDS(l) is equivalent to having (avera
 ge-case) combinatorial list decoding guarantees. They also show that being
  MDS(l) is equivalent to the generator matrix being able to achieve generi
 c zero patterns. Using the GM-MDS theorem which says that any Reed-Solomon
  codes achieve any generic zero pattern this implies that they generically
  achieve list decoding capacity.\nGuo-Zhang proved punctured Reed-Solomon 
 codes can achieve list decoding capacity over quadratic in 'n' size fields
  by introducing a slack to these notions (this was later strengthened to l
 inear by an improved argument due to Alrabiah\, Guruswami\, and Li). This 
 talk will cover these exciting developments and recent works by the speake
 r with Brakensiek\, Gopi\, and Zhang which develop this theory over codes 
 sampled from irreducible varieties\, prove a GM-MDS theorem for this setti
 ng\, and prove that punctured AG codes are list decodable up to capacity o
 ver constant size fields.\n \nShort Bio:\nManik Dhar is an Instructor (Po
 stdoc) of Applied Mathematics at Massachusetts Institute of Technology. He
  received his BTech at the Indian Institute of Technology - Bombay in 2016
 \, MS at Stanford University in 2018\, and received his PhD from Princeton
  in 2023 where he was advised by Zeev Dvir. He is broadly interested in di
 screte mathematics and theoretical computer science.\n
URL:https://www.tcs.tifr.res.in/web/events/1419
DTSTART;TZID=Asia/Kolkata:20240618T160000
DTEND;TZID=Asia/Kolkata:20240618T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1435
DTSTAMP:20240619T094028Z
SUMMARY:Tree evaluation in space O(log n . log log n)
DESCRIPTION:Speaker: Bikshan Chatterjee (TIFR)\n\nAbstract: \nTree Evaluati
 on was considered to be a candidate problem solvable in polynomial time bu
 t not in log space. The natural algorithm for performing tree evaluation t
 akes roughly log^2(n) space and was conjectured to be optimal. The belief 
 was based on an assumption that space being used for storing old values ca
 nnot be used for new computation. Cook and Mertz showed this assumption to
  be false\, in earlier work. In this paper\, they improve the space comple
 xity to O(log n . log log n) using similar strategy of reusing space being
  used for storing old values without erasing it.\n
URL:https://www.tcs.tifr.res.in/web/events/1435
DTSTART;TZID=Asia/Kolkata:20240621T140000
DTEND;TZID=Asia/Kolkata:20240621T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1436
DTSTAMP:20240622T142135Z
SUMMARY:Online Correlated Selection and related problems
DESCRIPTION:Speaker: Arghya Chakraborty (TIFR)\n\nAbstract: \nOnline Correl
 ated Selection (OCS) is a novel online selection problem introduced by Mat
 thew Fahrbach\, Zhiyi Huang\, Runzhou Tao\, Morteza Zadimoghaddam to obtai
 n improved online algorithm for thee dge-weighted bipartite matching probl
 em. In this talk\, I'll describe the OCS problem and describe an optimal a
 lgorithm for the 2-way OCS.We will then discuss extensions of the OCS prob
 lem as well as applications to the online edge-weighted bipartite matching
  problem.\n
URL:https://www.tcs.tifr.res.in/web/events/1436
DTSTART;TZID=Asia/Kolkata:20240624T143000
DTEND;TZID=Asia/Kolkata:20240624T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1439
DTSTAMP:20240626T093506Z
SUMMARY:Private Circuits
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \nConsider an ad
 versary which can look into a (boolean) circuit and runs an algorithm to m
 ake inferences about the signals carried by the components inside the circ
 uit. These algorithms are called side-channel attacks. In this talk\, we w
 ill see a theoretical model for these attacks and a scheme to protect the 
 circuit against these attacks under the given model. This talk will be bas
 ed on "Private circuits: Securing hardware against probing attacks" by Ish
 ai\, Sahai and Wagner in CRYPTO 2003\, one of the first papers which intro
 duced this problem.\n
URL:https://www.tcs.tifr.res.in/web/events/1439
DTSTART;TZID=Asia/Kolkata:20240627T160000
DTEND;TZID=Asia/Kolkata:20240627T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1440
DTSTAMP:20240627T094235Z
SUMMARY:On the Satisfaction Probability of k-CNF Formulas
DESCRIPTION:Speaker: Koduri Choudary (TIFR)\n\nAbstract: \nWe will be prese
 nting a paper of Till Tantau (with the above title)\, that appeared in CCC
  2022.\nThe Satisfaction Probability $\\sigma(\\phi)$ of a propositional f
 ormula $\\phi$ is the probability that a random assignment of variables sa
 tisfies the formula. This paper studies the complexity of the problem $k$S
 AT-PROB$_{>\\delta}=\\{\\phi\\in k$CNF$|\\sigma(\\phi)>\\delta\\}$ for fix
 ed $k\\in\\mathbb{N}$ and $\\delta\\in[0\,1]$. While the complexity of a f
 ew examples were already known (eg: 3SAT-PROB$_{>0}\\in$ NP-Complete)\, Ak
 mal and Williams have recently showed that 3SAT-PROB$_{>\\frac{1}{2}}\\in$
  P and 4SAT-PROB$_{>\\frac{1}{2}}\\in$ NP-Complete. In this paper\, the au
 thor gives a complete characterisation in the form of a trichotomy (i.e. $
 k$SAT-PROB$_{>\\delta}$ is in AC$^0$ or NL-Complete or NP-Complete) based 
 on the parameters $k$ and $\\delta$.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1440
DTSTART;TZID=Asia/Kolkata:20240628T140000
DTEND;TZID=Asia/Kolkata:20240628T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1438
DTSTAMP:20240626T045748Z
SUMMARY:Counting Problems in Graphical Models
DESCRIPTION:Speaker: Vidya Sagar Sharma (TIFR)\n\nAbstract: \nA graphical m
 odel is a probabilistic model that uses a graph to represent conditional i
 ndependence relations between random variables. We study acyclic directed 
 graphical models\, where a DAG is used to represent conditional independen
 ce relations and causal relationships between random variables. In this mo
 del\, a DAG $D(V = \\{v_1\, v_2\, \\ldots\, v_n\\}\, E)$ represents a prob
 ability distribution $P$\, defined over a set of random variables $V$\, if
  $P(v_1\, v_2\, \\ldots\, v_n) = \\prod_{i}{P(v_i | \\text{Parent}(v_i))}$
 . A node $v_i$ is said to be a parent of $v_j$ in a DAG if $v_i \\rightarr
 ow v_j$ is an edge in $G$. A DAG entails a conditional independence relati
 on $X \\perp Y \\mid Z$ if all the probability distributions represented b
 y the DAG satisfy the conditional independence relation. There can be more
  than one DAG that entails the same set of conditional independence relati
 ons. Such DAGs are said to be Markov equivalent. Markov equivalent DAGs be
 long to the same equivalence class\, called a Markov equivalence class (ME
 C)\, which is graphically represented by the union of the DAGs it contains
 .Many interesting combinatorial problems related to MECs exist in the lite
 rature. One such combinatorial problem is: Given the graphical representat
 ion of an MEC\, find the size of the MEC. The problem arises from the fact
  that a DAG is also used as a causal graph where a directed edge $X \\righ
 tarrow Y$ implies that $X$ is a direct cause of $Y$\, and the size of an M
 EC measures the uncertainty of the causal model when relying solely on obs
 ervational data. In applications\, more information about the underlying D
 AG than that encoded in the MEC may be available\, for example due to acce
 ss to some special set of interventions\, or some domain-specific knowledg
 e. Meek referred to this as \\emph{background knowledge}\, and modeled it 
 as a specification of the directions of some of the edges of the underlyin
 g DAG. Wienöbst et al. show that counting such background knowledge-consi
 stent DAGs of an MEC is \\#P-hard. In this talk\, we discuss an FPT algori
 thm for this problem. Another interesting combinatorial problem is: Given 
 an undirected graph $G$\, count the number of MECs that have the same skel
 eton as $G$. MECs with the same skeleton have statistical significance. In
  this talk\, we discuss an FPT algorithm that counts MECs with the same sk
 eleton. We also discuss an FPT algorithm that counts MECs with better time
  complexity than the previous algorithm when the input graph is chordal. A
 dditionally\, we discuss a polynomial algorithm to solve the problem when 
 the input graph is a tree.\n
URL:https://www.tcs.tifr.res.in/web/events/1438
DTSTART;TZID=Asia/Kolkata:20240628T160000
DTEND;TZID=Asia/Kolkata:20240628T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1431
DTSTAMP:20240627T051715Z
SUMMARY:Fair Sparse Regression with Clustering: An Invex Relaxation for a C
 ombinatorial Problem
DESCRIPTION:Speaker: Adarsh Barik (National University of Singapore (NUS))\
 n\nAbstract: \nIn this talk\, we discuss the problem of fair sparse regres
 sion on a biased dataset where bias depends upon a hidden binary attribute
 . The presence of a hidden attribute adds an extra layer of complexity to 
 the problem by combining sparse regression and clustering with unknown bin
 ary labels. The corresponding optimization problem is combinatorial\, but 
 we propose a novel reformulation of it as an invex optimization problem. W
 e show that the inclusion of the debiasing/fairness constraint in our mode
 l has no adverse effect on the performance. Rather\, it enables the recove
 ry of the hidden attribute. The support of our recovered regression parame
 ter vector matches exactly with the true parameter vector. Moreover\, we s
 imultaneously solve the clustering problem by recovering the exact value o
 f the hidden attribute for each sample. Our method uses carefully construc
 ted primal-dual witnesses to provide theoretical guarantees for the combin
 atorial problem. We show that the sample complexity of our method is logar
 ithmic in terms of the dimension of the regression parameter vector.\nShor
 t Bio:\nAdarsh Barik is a postdoc at the Institute of Data Science at the 
 National University of Singapore. He did his PhD in Computer Science at Pu
 rdue University and his undergrad at IIT Madras before that. His research 
 interests are broadly in theoretical and computational aspects of optimiza
 tion\, machine learning\, information theory\, and high-dimensional data a
 nalysis.\n
URL:https://www.tcs.tifr.res.in/web/events/1431
DTSTART;TZID=Asia/Kolkata:20240701T160000
DTEND;TZID=Asia/Kolkata:20240701T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1437
DTSTAMP:20240626T042022Z
SUMMARY:A Formal Approach to Exchange Design and Regulation
DESCRIPTION:Speaker: Suneel Sarswat (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1437
DTSTART;TZID=Asia/Kolkata:20240705T113000
DTEND;TZID=Asia/Kolkata:20240705T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1442
DTSTAMP:20240704T065450Z
SUMMARY:(Δ + 1) Vertex Coloring in O(n) communication
DESCRIPTION:Speaker: Parth Mittal (University of Waterloo)\n\nAbstract: \nI
  will talk about the communication complexity of (Δ+1) vertex coloring\, 
 where the edges of an n-vertex graph of maximum degree Δ are partitioned 
 between two players. I will show a randomized protocol which uses O(n) bit
 s of communication and ends with both players knowing the coloring. Combin
 ed with a folklore Ω(n) lower bound\, this settles the randomized communi
 cation complexity of (Δ+1)-coloring up to constant factors.Based on joint
  work with Maxime Flin.\n
URL:https://www.tcs.tifr.res.in/web/events/1442
DTSTART;TZID=Asia/Kolkata:20240705T143000
DTEND;TZID=Asia/Kolkata:20240705T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1443
DTSTAMP:20240709T062350Z
SUMMARY:Limitations of Massively Parallel Constant-time Algorithms
DESCRIPTION:Speaker: Vaibhav Krishan (Indian Institute of Technology\, Bomb
 ay)\n\nAbstract: \nHow many processors are needed to compute a function in
  constant-time by a massively parallel algorithm? We consider this questio
 n with the lens of Boolean circuits. Here\, we compose logic gates\, acti
 ng as processors\, with the number of layers corresponding to the running
  time\, to compute a Boolean function.Hence\, the question we would like 
 to answer is: how many gates do we need in such a circuit to compute a ce
 rtain function if the circuit only has a constant number of layers? In p
 articular\, we are searching for explicit functions that require a very l
 arge number of gates\, with a given set of choices for the logic gates.An
 swers to such questions have implications in learning theory\, cryptograp
 hy\, and the study of randomness. In this talk\, I will discuss past and 
 recent progress on such questions. Then\, I will talk about a recent high
 er-order Fourier-analysis based approach\, proposed by Bhrushundi\, Hosse
 ini\, Lovett and Rao (ITCS 2019)\, towards resolving a thirty-five years 
 old conjecture. Afterwards\, I will describe our contribution in developi
 ng this approach\, where we propose studying the projection of an explici
 t set of vectors towards resolving this conjecture. The talk will conclu
 de with some implications towards other frontiers in the study of Boolean
  circuits.The work I will discuss in this talk was in collaboration with P
 rof. Sundar Vishwanathan at IIT Bombay.\nShort Bio:\nVaibhav Krishan is a
  recent PhD graduate from IIT Bombay\, where he worked under the supervis
 ion of Prof. Sundar Vishwanathan and Prof. Nutan Limaye. He has worked in
  the industry as a quantitative trader\, and as a data scientist\, after 
 completing his undergrad. \n
URL:https://www.tcs.tifr.res.in/web/events/1443
DTSTART;TZID=Asia/Kolkata:20240709T160000
DTEND;TZID=Asia/Kolkata:20240709T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1449
DTSTAMP:20240710T110123Z
SUMMARY:Sperner's lemma and the equidissection of regular polygons
DESCRIPTION:Speaker: Pranshu Gaba (TIFR)\n\nAbstract: \nEquidissection of a
  regular polygon is the problem of dissecting the polygon into triangles o
 f equal area. Given a regular n-gon and a positive integer m\, we ask if i
 t is possible to equidissect the n-gon into m triangles. To answer this qu
 estion\, we make use of Sperner's lemma along with some elementary number 
 theory. Sperner's lemma is a major combinatorial result that has found app
 lications in topics such as fixed-point computation and fair division.We s
 hall see Sperner's lemma and its proof\, and use it to solve the equidisse
 ction problem for regular polygons. We will also look at some polygons tha
 t cannot be equidissected into m triangles for any positive m. Finally\, w
 e will go over the equidissection problem for higher-dimensional hypercube
 s.References:- Monsky\, P. (1970). On Dividing A Square Into Triangles. Th
 e American Mathematical Monthly\, 77(2)\, 161–164. https://doi.org/10.1
 080/00029890.1970.11992441- Stein\, S. (2004). Cutting a Polygon into Tria
 ngles of Equal Areas. The Mathematical Intelligencer 26\, 17–21. https:
 //doi.org/10.1007/BF02985395\n
URL:https://www.tcs.tifr.res.in/web/events/1449
DTSTART;TZID=Asia/Kolkata:20240712T143000
DTEND;TZID=Asia/Kolkata:20240712T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1434
DTSTAMP:20240613T064040Z
SUMMARY:Vigyan Vidushi 2024
DESCRIPTION:Speaker: \n\nAbstract: \nThe STCS Vigyan Vidushi 2024 program
 me is a summer school to introduce women with undergraduate and postgradua
 te background to advanced topics in theoretical computer and systems scien
 ces. The two-week programme will be held during the period 15th July – 
 26th July 2024 at the TIFR Mumbai campus\, and will consist of short te
 chnical courses taught by faculty from STCS\, TIFR. Lectures will be sup
 plemented by problem-solving sessions\, to enhance students’ understandi
 ng.\nhttps://www.tcs.tifr.res.in/~stcs-vv-24/\n \n
URL:https://www.tcs.tifr.res.in/web/events/1434
DTSTART;VALUE=DATE:20240715
DTEND;VALUE=DATE:20240727
LOCATION:TIFR\, Mumbai.
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1451
DTSTAMP:20240711T102852Z
SUMMARY:Matchings and Popularity
DESCRIPTION:Speaker: Kavitha  Telikepalli (TIFR)\n\nAbstract: \nThe problem
  of computing a stable matching in a bipartite graph is an old and well-st
 udied problem. Gale and Shapley showed in 1962 that such a matching always
  exists and can be efficiently computed. This is a classical result in alg
 orithms with many applications in economics and computer science. Stabilit
 y is a strong and rather restrictive notion. This talk will be on a relaxa
 tion of stability called ‘popularity’ and we will see simple and effic
 ient algorithms for some popular matching problems. No background in algor
 ithms or matching theory will be assumed.\nShort Bio:\nKavitha is professo
 r at the School of Technology and Computer Science at TIFR Mumbai and s
 he is also the dean of our school. Prior to joining TIFR\, she was a facul
 ty at the Indian Institute of Science (Bengaluru) and a postdoc at Max-Pla
 nck Institute for Informatics\, Saarbrücken. Her primary interests are in
  the graph algorithms and combinatorial optimisation\, and has made founda
 tional contributions in the area of graph matchings.\n
URL:https://www.tcs.tifr.res.in/web/events/1451
DTSTART;TZID=Asia/Kolkata:20240715T160000
DTEND;TZID=Asia/Kolkata:20240715T170000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1447
DTSTAMP:20240710T065515Z
SUMMARY:Verification of Concurrent Programs Under Weak Memory
DESCRIPTION:Speaker: Krishna S. (Indian Institute of Technology\, Bombay)\n
 \nAbstract: \nThis is an overview of recent work on the verification of co
 ncurrent programs. Traditionally concurrent programs are interpreted under
  sequential consistency (SC). Even though SC is very intuitive and easy to
  use\, modern multiprocessors do not employ SC for performance reasons\, a
 nd instead use so-called ‘weak memory models’. Some of the well known 
 weak memory models in vogue among modern multiprocessor architectures are 
 Intel x-86\, IBM POWER and ARM. The use of weak memory is also prevalent i
 n the C11 model\, leading to the release acquire fragment of C11. In this 
 talk\, I will introduce some of these memory models\, as well as recent ef
 forts in the verification of programs under these.\nShort Bio:\nKrishna is
  a professor at the Department of Computer Science and Engineering at th
 e Indian Institute of Technology\, Bombay. She obtained her PhD from IIT 
 Madras. Her primary interests are in the areas of automata theory\, logic\
 , and formal verification of timed and probabilistic systems.\n
URL:https://www.tcs.tifr.res.in/web/events/1447
DTSTART;TZID=Asia/Kolkata:20240718T160000
DTEND;TZID=Asia/Kolkata:20240718T170000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1453
DTSTAMP:20240719T064159Z
SUMMARY:Catch them if you can
DESCRIPTION:Speaker: Juhi Chaudhary (TIFR)\n\nAbstract: \nThe Cops and Robb
 er game is a well-studied two-player pursuit-evasion game played on graphs
 \, where a team of cops attempts to capture a robber. The cop number of a 
 graph represents the minimum number of cops required for a successful capt
 ure. Graphs with a cop number of one are known as cop-win graphs. In this 
 seminar\, I will begin by characterizing cop-win graphs. Subsequently\, I 
 will demonstrate\, using the technique of guarding a subgraph—a method f
 or bounding the cop number of graphs with geometric representations—that
  the cop number for planar graphs is atmost three.\n
URL:https://www.tcs.tifr.res.in/web/events/1453
DTSTART;TZID=Asia/Kolkata:20240720T143000
DTEND;TZID=Asia/Kolkata:20240720T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1445
DTSTAMP:20240725T063708Z
SUMMARY:Using AI to assist in improving maternal and child health outcomes 
 in underserved communities in India
DESCRIPTION:Speaker: Aparna Taneja (Google Research India)\n\nAbstract: \n\
 nThe widespread availability of cell phones has enabled non-profits to del
 iver critical health information to their beneficiaries in a timely manner
 . This project assists non-profits that employ automated messaging program
 s to deliver timely preventive care information to beneficiaries (new and 
 expecting mothers) during pregnancy and after delivery. Unfortunately\, a 
 key challenge in such information delivery programs is that a significant 
 fraction of beneficiaries drop out of the program. Yet\, non-profits often
  have limited health-worker resources (time) to place crucial service call
 s for live interaction with beneficiaries to prevent such engagement drops
 . To assist non-profits in optimizing this limited resource\, we developed
  a Restless Multi-Armed Bandits (RMABs) system. The RMAB system was evalua
 ted in collaboration with an NGO via a real-world service quality improvem
 ent study and showed a 30% reduction in engagement drops. This model was e
 ventually deployed by the NGO and has served over 350K women so far. These
  encouraging results have led to a new collaboration with the Kilkari prog
 ram\, the largest maternal mHealth program in the world. And we hope to se
 e similar improvements in engagement with the use of our AI model.\n \nS
 hort Bio:\nAparna is a researcher at the Multi Agents Systems for Social I
 mpact team in Google Research India. She received her PhD in Computer Sci
 ence at ETH Zurich under the supervision of Prof. Marc Pollefeys. She then
  pursued a postdoc at Disney Research Zurich. She collaborates with severa
 l NGO’s and academic partners in the fields of public health and conserv
 ation and her primary focus is collaboration with ARMMAN\, an NGO focused
  on improving maternal and child health outcomes in underserved communitie
 s in India.\n
URL:https://www.tcs.tifr.res.in/web/events/1445
DTSTART;TZID=Asia/Kolkata:20240725T170000
DTEND;TZID=Asia/Kolkata:20240725T180000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1448
DTSTAMP:20240726T041235Z
SUMMARY:Faul Tolerant Distance Oracles
DESCRIPTION:Speaker: Dipan Dey (IIT Gandhinagar)\n\nAbstract: \nThe shortes
 t distance and shortest paths between vertices are very important aspects 
 of Graph Theory. Graphs are often used to represent real-life networks and
  real-life networks are often prone to failures. Due to those failures\, w
 e may want to avoid some edges in the graph at some point of time. \nHenc
 e\, we may want to find the shortest distance and the shortest path betwee
 n two vertices while avoiding some edges or vertices in the graph. Fault-t
 olerant distance oracles are oracles or a set of data structures which can
  answer those kinds of queries. In my talk\, I will be discussing some of 
 our results related to fault-tolerant distance oracles.\nShort Bio: \nDipa
 n obtained a B.Sc. (Hons.) in Mathematics from Vidyasagar College (Kolkata
 ) and an M.Sc. in Mathematics from Banaras Hindu University. During his po
 stgraduate studies at Banaras Hindu University\, he developed an interest 
 in graph theory. He then joined the CSE discipline at IIT Gandhinagar to p
 ursue a PhD under Prof. Manoj Gupta's supervision. His thesis focuses on f
 ault-tolerant distance oracles\, the data structures that can determine di
 stances between vertices while avoiding some edges or vertices. In additio
 n to his thesis work\, he has also worked on linear rank width one graphs 
 and power graphs.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1448
DTSTART;TZID=Asia/Kolkata:20240726T100000
DTEND;TZID=Asia/Kolkata:20240726T110000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1455
DTSTAMP:20240722T064620Z
SUMMARY:Bandit Problems with Rare Rewards
DESCRIPTION:Speaker: Anirban Bhattacharjee (TIFR)\n\nAbstract: \nIn this ta
 lk\, we will examine bandit algorithms in the special and relevant case of
  rarely occuring rewards. This problem will be seen from the perspective o
 f both fixed confidence and fixed budget settings. In both these settings\
 , we have been able to use approximate methods to drastically reduce the c
 omputational complexity of existing algorithms. We have also devised an al
 gorithm to select the best system from a given collection of highly reliab
 le systems\, where failures are rare events. \n
URL:https://www.tcs.tifr.res.in/web/events/1455
DTSTART;TZID=Asia/Kolkata:20240726T110000
DTEND;TZID=Asia/Kolkata:20240726T120000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1457
DTSTAMP:20240724T062538Z
SUMMARY:A randomized algorithm for estimate volumes of convex
DESCRIPTION:Speaker: Sourav  Roy (TIFR)\n\nAbstract: \nI will present a ran
 domized volume algorithm from the  paper "Volume Estimates and Rapid Mixi
 ng " by Bela Bollobas. The goal is to find a fully polynomial approximatio
 n scheme (FPRAS) for approximating the volume of a convex body K in R^n. A
  randomized algorithm that runs in time polynomial in <K>\, 1/ (\\epsilon)
   and log(1/\\nu)\, and with probability at least (1 − \\nu) produces a
 n \\epsilon-approximation to vol(K). Here the input is (r\, R\, n) for  K
   satisfying  rB^n \\subset  K  \\subset RB^n   with <K> = n + <r> 
 + <R>\, where <x> is the number of binary digits of a dyadic rational x.\n
URL:https://www.tcs.tifr.res.in/web/events/1457
DTSTART;TZID=Asia/Kolkata:20240726T160000
DTEND;TZID=Asia/Kolkata:20240726T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1458
DTSTAMP:20240726T100756Z
SUMMARY:Optimal Strategies and Minimax Lower Bounds for Online Convex Games
DESCRIPTION:Speaker: Pranab Panda (TIFR)\n\nAbstract: \nhttps://www.learnin
 gtheory.org/colt2008/papers/111-Abernethy.pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1458
DTSTART;TZID=Asia/Kolkata:20240729T160000
DTEND;TZID=Asia/Kolkata:20240729T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1430
DTSTAMP:20240722T043818Z
SUMMARY:Type-Checking for Pattern-Based Tree Transformations
DESCRIPTION:Speaker: M. Praveen (Chennai Mathematical Institute)\n\nAbstrac
 t: \nWe introduce and study pattern-based tree transformations. Consider (
 +(.(x\, y)\, .(x\, z))\, .(x\, +(y\, z)))\, a pair of a source pattern and
  a target pattern. This source pattern matches any expression e of the for
 m +(.(e1 \, e2 )\, .(e1 \, e3 ))\, by substituting e1 for x\, e2 for y and
  e3 for z. Note that the set of such matching expressions is not a regular
  tree language\, since the same expression must appear in two locations wh
 ere x appears in the source pattern. This pair transforms the expression e
  into the expression .(e1 \, +(e2 \, e3 )) (obtained by applying the same 
 substitution to the target pattern). Our model finitely represents a (poss
 ibly infinite) set of such (source pattern\, target pattern) pairs. The ex
 pressive power of this model comes at the cost of undecidability of checki
 ng equivalence. The type-checking problem checks whether applying a given 
 transformation to trees having a given regular property (type) preserves t
 he property. We show that this problem is decidable for pattern-based tree
  transformations. Our decision procedure is by a reduction to the emptines
 s problem of alternating tree automata.This is joint work with C. Aiswarya
  and Sahil Mhaskar from Chennai Mathematical Institute.\nShort Bio:\nPrave
 en is an associate professor at Chennai Mathematical Institute. He finishe
 d PhD at the Institute of Mathematical Institute\, Chennai. He was a postd
 oc at LSV\, ENS Cachan and LaBRI\, University of Bordeaux before he joined
  CMI in 2014. His research interests and logic and automata theory for for
 mal verification.\n
URL:https://www.tcs.tifr.res.in/web/events/1430
DTSTART;TZID=Asia/Kolkata:20240730T160000
DTEND;TZID=Asia/Kolkata:20240730T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1459
DTSTAMP:20240801T054230Z
SUMMARY:EFX Allocations on Graphs.
DESCRIPTION:Speaker: Yeshwant Chandrakant  Pandit (TIFR)\n\nAbstract: \nIn 
 this talk\, we will explore envy-freeness up to any good (EFX) in settings
  where valuations are represented by a graph of arbitrary size\, with vert
 ices corresponding to agents and edges corresponding to items. An item (ed
 ge) has zero marginal value to all agents (vertices) not incident to the e
 dge. Each vertex may have an arbitrary monotone valuation on the set of in
 cident edges. We will first examine allocations that correspond to edge or
 ientations\, noting that EFX may not always be achievable. Furthermore\, d
 etermining whether an EFX orientation exists is NP-complete. The main resu
 lt is that EFX allocations exist for this setting. This is one of the few 
 cases where EFX allocations are known to exist for more than 3 agents.\nRe
 ference: https://dl.acm.org/doi/pdf/10.1145/3580507.3597764\n \n
URL:https://www.tcs.tifr.res.in/web/events/1459
DTSTART;TZID=Asia/Kolkata:20240802T143000
DTEND;TZID=Asia/Kolkata:20240802T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1441
DTSTAMP:20240722T043611Z
SUMMARY:Equivalence Testing of Principal Minors
DESCRIPTION:Speaker: Roshan Raj (IIT Bombay)\n\nAbstract: \nFor a square ma
 trix A with n rows and n columns and a subset S of [n]\, the corresponding
  principal minor is the determinant of the submatrix of A with rows and co
 lumns indexed by elements in S i.e. det(A[S\, S]). Two operations on a mat
 rix A that preserve all the principal minors are:\nTaking the transpose of
  the matrix.\nMultiplying it by an invertible diagonal matrix on one side 
 and by its inverse on the other.\nThe matrices DAD^{-1} and DA^TD^{-1} are
  called diagonally similar to A when D is an invertible diagonal matrix.\n
 For a square matrix A of dimension n\, a subset S of [n] of size at least 
 two and at most n-2 is called a cut if the rank of both the submatrices A[
 S\, [n]-S] and A[[n]-S\, S] is less than two. In a couple of works\, Rapha
 el and Loewy showed that for an irreducible matrix A with no cuts\, anothe
 r matrix B has the same principal minors if and only if B is diagonally si
 milar to A. \nIn this work\, we give an extension of their result by givi
 ng a complete characterization of when two matrices can have the same prin
 cipal minors and give a polynomial time algorithm to test it. We also pres
 ent some applications of equivalence testing of principal minors in Combin
 atorics and Polynomial Identity Testing.\nThis is joint work with Abhranil
  Chatterjee\, Rohit Gurjar\, and  Sumanta Ghosh.\nShort Bio:\nRoshan Raj 
 is a PhD student in the CSE department at IIT Bombay working under the me
 ntorship of Prof. Rohit Gurjar. He holds a Betch degree in CSE from IIT B
 HU.\n
URL:https://www.tcs.tifr.res.in/web/events/1441
DTSTART;TZID=Asia/Kolkata:20240802T160000
DTEND;TZID=Asia/Kolkata:20240802T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1424
DTSTAMP:20240801T044101Z
SUMMARY:Invitation to FPT Approximation via Cut and Coverage Problems
DESCRIPTION:Speaker: Saket Saurabh (The Institute of Mathematical Sciences)
 \n\nAbstract: \nIn this talk\, we will provide an introduction to the area
  of FPT-Approximation. The goal of this research area is to develop algori
 thms that are faster than known FPT algorithms and achieve better approxim
 ation factors than what is possible in polynomial time. We will explore re
 cent advances in this field through some classical cut and coverage proble
 ms\, such as k-Way Cut and Max-Coverage.\nShort Bio:\nSaket Saurabh receiv
 ed his PhD in Computer Science (2008)\, from The Institute of Mathe-matic
 al Sciences (IMSc)\, Chennai. Saurabh spent two years (2007-2009) as a Po
 stdoctoral Fellow at University of Bergen\, Norway\, and is now a profess
 or at IMSc.  He is a SwarnaJayanti Fellow in Mathematical Sciences (2018)
 \, Fellow of Indian Academy of Sciences (2020)\, Academia Europaea (2020)\
 , and European Association for Theoretical Computer Science (EATCS\, 2021
 ). He received the inaugural ACM India Early Career Researcher Award in 2
 020\, and Shanti Swarup Bhatnagar Prize (SSB) for Science and Technology 
 2021 (Mathematical Science).\n
URL:https://www.tcs.tifr.res.in/web/events/1424
DTSTART;TZID=Asia/Kolkata:20240806T160000
DTEND;TZID=Asia/Kolkata:20240806T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1452
DTSTAMP:20240801T044137Z
SUMMARY:Advances and Challenges in Fair Division: Quantiles\, Subsidies\, a
 nd Randomization
DESCRIPTION:Speaker: Vishnu V Narayan (McGill University\, Canada)\n\nAbstr
 act: \nThe question of how to fairly divide a collection of indivisible it
 ems amongst a set of agents has remained of central importance to humanity
  since antiquity. In this fundamental problem\, the agents have varied pre
 ferences\, and an allocator seeks to find a single allocation such that ev
 ery agent perceives its bundle as fair. This problem arises in various app
 lications\, ranging from classical examples like the division of inherited
  estates and international borders to modern applications such as assignin
 g seats in college courses and allocating computational resources fairly.R
 ecent decades have witnessed significant progress\, transforming this prob
 lem into a fascinating mathematical landscape with surprising results and 
 intriguing new challenges. The broad goal of the community is to devise de
 finitions of fairness that mirror our intuitive understanding of what it m
 eans to be fair\, and then study questions such as: does a fair allocation
  always exist?\; can one be (efficiently) computed?\; what are the precise
  limits to the degree of fairness one can guarantee? Fair division is emer
 ging as a major research area\, with an increasing number of publications 
 at Theory and AI conferences each year. In this talk\, I will focus on sel
 ected recent papers of mine\, highlighting three techniques (Quantiles\, S
 ubsidies\, and Randomization) we use to extend the study of fair allocatio
 ns to general valuation classes and resolve some conjectures and open prob
 lems. This talk will also provide an overview of my research trajectory an
 d plans for future work.\nShort Bio:\nVishnu V. Narayan is a postdoctoral 
 fellow hosted by Michal Feldman at Tel Aviv University. His main research 
 focus is on the fair division of indivisible items. He is also broadly int
 erested in the many intersections of combinatorics\, algorithms\, and game
  theory. He has a best paper award from SAGT 2019 and a Highlights Session
  selection at EC 2024. Earlier\, he completed his Ph.D. in Computer Scienc
 e at McGill University under the supervision of Adrian Vetta\, and his M.M
 ath. in Combinatorics and Optimization at the University of Waterloo with 
 Joseph Cheriyan.\n
URL:https://www.tcs.tifr.res.in/web/events/1452
DTSTART;TZID=Asia/Kolkata:20240807T110000
DTEND;TZID=Asia/Kolkata:20240807T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1461
DTSTAMP:20250715T083635Z
SUMMARY:Regret minimization in stochastic multi-armed bandits
DESCRIPTION:Speaker: Agniv Bandyopadhyay (TIFR)\n\nAbstract: \nIn the stoch
 astic K-armed bandit framework\, we are given K unknown distributions or a
 rms. At a given time\, we can select one arm and can observe one sample fr
 om that arm. Our goal is to maximize the reward over a finite time horizon
 \, which is also equivalent to minimizing the regret. Regret minimization 
 is an important aspect of many applications where we have to make sequenti
 al decisions under uncertainty and optimize for some objective\, for examp
 le\, clinical trials\,  recommendation systems\, selecting the best portf
 olio in a financial market\, etc. We will analyze some basic regret minimi
 zing algorithms\, such as: explore-then-commit\, successive reject\, upper
  confidence bound\, etc. We will also derive an information-theoretic lowe
 r bound on regret. \n \nThe talk will be based on the following referenc
 es: \n1. Lattimore\, Tor\, and Csaba Szepesvári. Bandit algorithms. Camb
 ridge University Press\, 2020\, Chapter 6-7.\n2. Kaufmann\, Emilie. Contri
 butions to the Optimal Solution of Several Bandit Problems. Diss. Universi
 té de Lille\, 2020\, Chapter 1.\n
URL:https://www.tcs.tifr.res.in/web/events/1461
DTSTART;TZID=Asia/Kolkata:20240809T160000
DTEND;TZID=Asia/Kolkata:20240809T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1460
DTSTAMP:20240807T043612Z
SUMMARY:STCS Annual Symposium
DESCRIPTION:Speaker: \n\nAbstract: \nThe STCS Symposium\, to be held on Aug
 ust 12-13 this year\, is an annual event where members showcase their rese
 arch work. This year's edition has several invited talks including the pre
 stigious Prof. R. Narasimhan Memorial Lecture.\nVisit STCS Annual Symposiu
 m 2024 page for more details.\n
URL:https://www.tcs.tifr.res.in/web/events/1460
DTSTART;VALUE=DATE:20240812
DTEND;VALUE=DATE:20240814
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1446
DTSTAMP:20240812T062023Z
SUMMARY:Recent progress on the online k-server problem
DESCRIPTION:Speaker: Amit Kumar (IIT Delhi)\n\nAbstract: \nThe k-server pro
 blem is one of the most fundamental problems in the area of online algorit
 hms. In this problem\, an online algorithm needs to maintain a set of k se
 rvers in a metric space. When a request arrives at a certain location\, on
 e of the k servers needs to move to this requested location. The goal is t
 o minimize the total movement cost of all the servers. Over the past three
  decades\, significant progress has been made on this problem\, yet many i
 ntriguing questions remain open. Notably\, progress on the k-server proble
 m has resulted in the development of new techniques that have advanced the
  broader field of online algorithms. This talk will survey recent techniqu
 es and breakthroughs developed for the k-server problem.\nShort Bio:\nAmit
  Kumar is a faculty member in the dept. of Computer Science and Engineeri
 ng at IIT Delhi. He obtained a B.Tech. degree from IIT Kanpur in 1997 and
  Ph.D. from Cornell University in 2002. He works in the area of combinato
 rial optimization\, with emphasis on problems arising in scheduling\, gra
 ph theory and clustering. Hereceived IBM Faculty Award in 2005\, INAE (Ind
 ian National Academy of Engineering) Young Engineer Award in 2006 and INS
 A (Indian National Science Academy) Medal for Young Scientists in 2011. H
 e was a Max Planck-India partner group research fellow during 2005-09. He
  received the prestigious Shanti Swarup Bhatnagar Award for Mathematical 
 Sciences in 2018\, and was elected Fellow of Indian Academy of Sciences i
 n 2019\, and Fellow of Indian National Academy of Engineering in 2022.\n
URL:https://www.tcs.tifr.res.in/web/events/1446
DTSTART;TZID=Asia/Kolkata:20240812T090000
DTEND;TZID=Asia/Kolkata:20240812T103000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1418
DTSTAMP:20240812T062049Z
SUMMARY:Verifying Programs in Weak Memory Models with persistency
DESCRIPTION:Speaker: Prakash Saivasan (The Institute of Mathematical Scienc
 es)\n\nAbstract: \nIn this talk\, we will consider the problem of verifyin
 g concurrent programs. In here\, we are given a set of programs that commu
 nicate through shared memory\, a specification and we wish algorithmically
  check if the programs violate the specification. The programmers\, while 
 writing code usually assume that the memory operations are immediate (refe
 rred to as sequential consistency). However\, the modern day architectures
 \, to optimise the running time\, re-order the memory operations in a non-
 trivial manner. This leads to various memory models such as TSO\, PSO and 
 so on. We will walk through some of these memory models during the talk. T
 he recent intel processor introduced persistency mechanism that allows for
  the writes to be archived. This can then be used to restart the computati
 on in case of a crash. The main focus of the talk will be how to verify pr
 ograms when persistency is combined with weak memory.\nShort Bio:\nPrakash
  Saivasan | The Institute of Mathematical Sciences (imsc.res.in)\n
URL:https://www.tcs.tifr.res.in/web/events/1418
DTSTART;TZID=Asia/Kolkata:20240813T093000
DTEND;TZID=Asia/Kolkata:20240813T103000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1456
DTSTAMP:20250514T052138Z
SUMMARY:The Compensated Coupling (or How the Future is the Great Guide for 
 the Present)
DESCRIPTION:Speaker: Siddhartha Banerjee (Cornell University)\n\nAbstract: 
 \nI will present the compensated coupling: a simple paradigm for designing
  sequential decision-making policies based on sample-pathwise comparisons 
 against a hindsight benchmark. This approach generalizes many standard res
 ults used in studying Markov decision processes and reinforcement learning
 \, but also gives us new policies which are much simpler and more effectiv
 e than existing heuristics. For a large class of widely-studied sequential
  decision-making problems -- including network revenue management\, dynami
 c pricing\, generalized assignment\, online bin packing\, online assortmen
 t optimization and bandits with knapsacks -- I will illustrate how under a
  wide range of conditions\, our approach achieves additive loss compared t
 o the hindsight optimal which is independent of the horizon and state-spac
 e. Time permitting\, I will try and describe how we can use this technique
  to incorporate side information and historical data\, and achieve constan
 t regret with as little as a single data trace.\nShort Bio:\nSid Banerjee 
 is an associate professor in the School of Operations Research at Cornell\
 , working on topics at the intersection of data-driven decision-making\, n
 etwork algorithms and market design. His research is supported by grants f
 rom the NSF (including an NSF CAREER award)\, ARO\, AFOSR\, and Engaged Co
 rnell\, and has received multiple awards including the INFORMS Applied Pro
 bability Society Best Publication award in 2021 and the Erlang Prize in 20
 22. He received his B.Tech from IIT Madras and PhD from the ECE Department
  at UT Austin\, and was a postdoctoral researcher in the Social Algorithms
  Lab at Stanford. He also served as a technical consultant with the resear
 ch science group at Lyft from 2014-18.\n
URL:https://www.tcs.tifr.res.in/web/events/1456
DTSTART;TZID=Asia/Kolkata:20240813T143000
DTEND;TZID=Asia/Kolkata:20240813T153000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1463
DTSTAMP:20240816T063415Z
SUMMARY:EFX Allocation Exists for Three Agents
DESCRIPTION:Speaker: Soumyajit Pyne (TIFR)\n\nAbstract: \n In 2020\, Chaud
 hury\, Garg\, and Mehlhorn demonstrated the existence of EFX allocation fo
 r three agents with additive valuations\, though their proof is complex an
 d lengthy. Subsequently\, Akrami et al. developed a simpler proof of this 
 result. In the seminar talk\, we will review their proof. As of now\, the 
 existence of EFX for more than three agents remains unknown.\nLink to the 
 paper: https://arxiv.org/abs/2205.07638.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1463
DTSTART;TZID=Asia/Kolkata:20240816T160000
DTEND;TZID=Asia/Kolkata:20240816T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1444
DTSTAMP:20240812T061508Z
SUMMARY:Exponential lower bounds via Exponential sums
DESCRIPTION:Speaker: Somnath Bhattacharjee (Chennai Mathematical Institute)
 \n\nAbstract: \nValiant's famous VP vs. VNP conjecture states that the sym
 bolic permanent polynomial does not have polynomial-size algebraic circuit
 s. However\, the best upper bound on the size of the circuits computing th
 e permanent is exponential. Informally\, VNP is an exponential sum of VP-c
 ircuits. In this paper we study whether\, in general\, exponential sums of
  algebraic circuits require exponential-size algebraic circuits. We show t
 hat the famous Shub-Smale tau-conjecture indeed implies such an exponentia
 l lower bound for an exponential sum. Our main tools come from parameteriz
 ed complexity. Along the way\, we also prove an exponential fpt (fixed-par
 ameter tractable) lower bound for the parameterized algebraic complexity c
 lass VW[P]\, weighted sum circuits (constant-free\, unbounded degree)\, as
 suming the same conjecture. VW[P] can be thought of as the weighted sums o
 f (unbounded-degree) circuits\, where only +1/-1 constants are cost-free. 
 To the best of our knowledge\, this is the first time the Shub-Smale tau-c
 onjecture has been applied to prove explicit exponential lower bounds. Fur
 thermore\, we prove that when this class is fpt\, then a variant of the co
 unting hierarchy\, namely the linear counting hierarchy collapses. Moreove
 r\, if a certain type of parameterized exponential sums is fpt\, then inte
 gers\, as well as polynomials with coefficients being definable in the lin
 ear counting hierarchy have subpolynomial tau-complexity. Finally\, we sho
 wed a completeness result on a subclass VW[F] (weighted sum of formulas)\n
  \nThis talk is based on joint work with Markus Blaser (University of Saa
 rland)\, Pranjal Dutta (NUS) and Saswata Mukherjee (NUS) [ICALP 2024]\, li
 nk: https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2024
 .24\n \nShort Bio:\nSomnath completed his Bachelors and Masters from the 
 Chennai Mathematical Institute and is on his way to the University of Toro
 nto for his PhD. His current research interests are in algorithms and comp
 lexity with a focus on problems with an algebraic flavor\, including algeb
 raic complexity\, algebraic algorithms\, pseudorandomness\, algebraic proo
 f complexity and error correcting codes.\n
URL:https://www.tcs.tifr.res.in/web/events/1444
DTSTART;TZID=Asia/Kolkata:20240819T160000
DTEND;TZID=Asia/Kolkata:20240819T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1433
DTSTAMP:20240819T052756Z
SUMMARY:Wait ... even my phone charger can steal my data?
DESCRIPTION:Speaker: Purushottam Kar (IIT Kanpur)\n\nAbstract: \nIn the con
 text of cybersecurity\, a side-channel attack operates by targeting the im
 plementation of an algorithm or protocol rather than identifying flaws in 
 the algorithm or protocol itself. We explore a family of such attacks\, ut
 ilizing the electromagnetic (EM) or power channels to perform exfiltration
  i.e.\, steal data from a device. Specifically\, we study the exfiltration
  of AI/ML models operating inside a device using a limited number of "prob
 es". Our path to this nefarious goal takes us through the seemingly unrela
 ted problem of how permutations induced by the quotient groups Z/NZ and (Z
 /NZ)^x act upon the Hamming topology. We arrive at novel results in this d
 irection that allow disturbingly efficient attacks using a small number of
  probes. These attacks target simple arithmetic operations such as additio
 n or multiplication carried out while an AI/ML model is performing inferen
 ce. The talk will present a short guided tour of this study and conclude w
 ith some fascinating yet open questions thereby surfaced.\nShort Bio:\nRoo
 p is a member of the IIT Kanpur faculty. He finds the IITK campus so nice 
 that he graduated from it twice. He is fascinated by machine learning and 
 optimization and has thus far managed to convince his employers that he un
 derstands these areas decently. Consequently\, they let him stick around w
 hile he explores ways to use ML to achieve clean-air objectives\, assist i
 n teaching comically large class sizes\, reveal and mitigate cybersecurity
  threats\, and make rich corporations even richer.\n
URL:https://www.tcs.tifr.res.in/web/events/1433
DTSTART;TZID=Asia/Kolkata:20240820T160000
DTEND;TZID=Asia/Kolkata:20240820T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1465
DTSTAMP:20240821T100350Z
SUMMARY:Making a Trifference
DESCRIPTION:Speaker: Siddharth Bhandari (Toyota Technological Institute)\n\
 nAbstract: \n\nA subset C⊆{0\,1\,2}^n is said to be a trifferent code (o
 f block length n) if for every three distinct codewords x\,y\,z∈C\, ther
 e is a coordinate i∈{1\,2\,...\,n} where they all differ\, that is\, {x(
 i)\,y(i)\,z(i)} is same as {0\,1\,2}. Let T(n) denote the size of the larg
 est trifferent code of block length n. Understanding the asymptotic behavi
 or of T(n) is closely related to determining the zero-error capacity of th
 e (3/2)-channel defined by Elias'58\, and is a long-standing open problem 
 in the area. Elias had shown that T(n)≤2×(3/2)^n and prior to our work 
 the best upper bound was T(n)≤0.6937×(3/2)^n due to Kurz'23 obtained vi
 a a computer search. \n \nIn this talk we will see an improved bound of 
 T(n)≤c×n^(−0.4)×(3/2)^n where c is an absolute constant. First\, we 
 will go over some history of the problem and explore its connections to ze
 ro-error information theory\, perfect hashing and graph covering. Then\, w
 e will go over the main ideas of the proof and several interesting open qu
 estions.\nShort Bio:\nSiddharth Bhandari is currently serving as a Researc
 h Assistant Professor at the Toyota Technological Institute in Chicago. Pr
 ior to this\, he was a Simons-Berkeley Fellow at the Simons Institute for 
 the Theory of Computing. Siddharth completed his Ph.D. at the School of Te
 chnology and Computer Science at the Tata Institute of Fundamental Researc
 h\, Mumbai. His research interests lie in exploring interdisciplinary dire
 ctions with a focus on developing techniques from computer science. He has
  worked and continues to work in the areas of coding/information theory\, 
 MCMC sampling algorithms\, and causal inference.  Siddharth's work has b
 een recognized with several awards. His dissertation work was awarded the 
 ACM India Dissertation Award. His paper "Improved Bounds for Perfect Sampl
 ing of k-Colorings in Graphs" won the Danny Lewin Best Student Paper Award
  at STOC 2020. He also won the Jack Keil Wolf Student Paper Award at ISIT 
 2018 for his work "Bounds on the Zero-Error List-Decoding Capacity of the 
 q/(q−1) Channel.\n
URL:https://www.tcs.tifr.res.in/web/events/1465
DTSTART;TZID=Asia/Kolkata:20240826T100000
DTEND;TZID=Asia/Kolkata:20240826T110000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1417
DTSTAMP:20240827T094728Z
SUMMARY:Colorful Extensions of Infinite (p\,q)-Theorems in Combinatorial Ge
 ometry
DESCRIPTION:Speaker: Arijit Ghosh (Indian Statistical Institute)\n\nAbstrac
 t: \nAn infinite sequence of sets  is said to be a heterochromatic sequ
 ence for an infinite collection  of families of sets\, if there exists 
 a strictly increasing sequence of natural numbers  such that for all  
 we have . In this talk\, we will prove  that if for each  is a family 
 of nicely shaped convex sets in  such that each heterochromatic sequen
 ce  of  contains  sets that can be pierced by a single  -flat ( -d
 imensional affine space) then all but finitely many 's can be pierced by 
 finitely many -flats. This result generalizes the -Theorem proved by 
  Keller and Perles (SoCG'22) to the countably colorful setting. We have a
 lso established the tightness of our results by proving several no-go the
 orems.\nThis is a joint work with Sutanoya Chakraborty (PhD Student at ISI
 \, Kolkata) and Soumi Nandi (PhD Student at ISI\, Kolkata).\nShort Bio:\nA
 rijit Ghosh is currently an Associate Professor at ACM Unit\, Indian Stati
 stical Institute\, Kolkata. He did his PhD in Computer Science from INRIA\
 , France\, and was a Postdoc at Max Planck Insitute for Informatics\, Ger
 many.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1417
DTSTART;TZID=Asia/Kolkata:20240827T160000
DTEND;TZID=Asia/Kolkata:20240827T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1470
DTSTAMP:20240828T041544Z
SUMMARY:An introduction to fairness in reinforcement learning.
DESCRIPTION:Speaker: Vishakha Patil (Indian Institute of Science\, Bangalor
 e)\n\nAbstract: \nIn a series of three talks\, we present an overview of w
 ork in bandit optimization\, including stochastic and adversarial bandits\
 , and will focus on variants of multi-armed bandits where fairness is an a
 dditional constraint. In Fair-MAB\, for example\, in addition to the objec
 tive of maximizing the sum of expected rewards\, the algorithm also needs 
 to ensure that at any time\, each arm is pulled at least a pre-specified f
 raction of times. We investigate the interplay between learning and fairne
 ss in such settings\, and also investigate the cost of fairness.Talk 1: Th
 ursday 29/8\, 2 - 3:30 pm in A-238Talk 2: Friday 30/8\, 4 - 5:30 pm in A-2
 01Talk 3: Monday 2/9\, 2 - 3:30 pm in A-238\nShort Bio:\nVishakha Patil wo
 rks in online learning and optimization\, game theory\, and mechanism desi
 gn. She completed her PhD from IISc\, supported by a Google Fellowship and
  a CII-SERB PMRF. She has also been a Heidelberg Laureate Forum Young Rese
 archer\, and her MTech thesis received an Honourable Mention for the Best 
 Thesis Award at CSA\, IISc.\n
URL:https://www.tcs.tifr.res.in/web/events/1470
DTSTART;TZID=Asia/Kolkata:20240829T140000
DTEND;TZID=Asia/Kolkata:20240829T150000
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1472
DTSTAMP:20240830T040206Z
SUMMARY:Adversarial Multi-Armed Bandit and the EXP3 Algorithm.
DESCRIPTION:Speaker: Vishakha Patil (Indian Institute of Science\, Bangalor
 e)\n\nAbstract: \nIn this talk\, we will look at the Adversarial Multi-Arm
 ed Bandit problem. In this model\, as the name suggests\, the rewards are 
 chosen by an adversary. We then present the EXP3 algorithm\, a well-known 
 algorithm for regret minimization in Adversarial Bandits\, and analyze its
  regret.\n
URL:https://www.tcs.tifr.res.in/web/events/1472
DTSTART;TZID=Asia/Kolkata:20240830T160000
DTEND;TZID=Asia/Kolkata:20240830T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1471
DTSTAMP:20240830T053500Z
SUMMARY:Public Quantum Network: The First Node
DESCRIPTION:Speaker: Keshav Kapoor (University of Illinois Urbana-Champaign
 )\n\nAbstract: \nQuantum networks are being developed around the globe in 
 order to facilitate cryptographic systems\, improve metrology\, and advanc
 e quantum computing systems. These networks have yet to be made readily av
 ailable to the general public. We have developed a publicly accessible qua
 ntum network node\, located in Urbana-Champaign.  We utilize a polarizati
 on-based entanglement source located at the University of Illinois Urbana-
 Champaign. One of the photons from the source is routed through fiber opti
 c cables to the Urbana Free Library\, a public library. In order to introd
 uce quantum mechanics concepts we develop a series of displays\, activitie
 s\, and written resources that build up to quantum entanglement and encour
 age people to directly interact with photons in the network. These resourc
 es culminate in a projection measurement system located in the library\, w
 here the public can choose measurement bases and perform their own CHSH in
 equality measurements.\nShort Bio:\nKeshav Kapoor received the B.A. degree
  in physics and applied mathematics from the University of California\, Be
 rkeley\, in 2021. He is currently pursuing the Ph.D. degree at the Univers
 ity of Illinois Urbana–Champaign advised by professors Paul Kwiat and Vi
 rginia Lorenz. His research focuses on quantum information science\, optic
 s\, and networks. Before starting the PhD program\, he was a Quantum Compu
 ting Associate with the Fermi National Accelerator Laboratory (Fermilab)\,
  where he had been working on the FQNET Project.\n
URL:https://www.tcs.tifr.res.in/web/events/1471
DTSTART;TZID=Asia/Kolkata:20240902T100000
DTEND;TZID=Asia/Kolkata:20240902T110000
LOCATION:H.B.A. Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1468
DTSTAMP:20240829T095226Z
SUMMARY:Performativity in Reinforcement Learning
DESCRIPTION:Speaker: Debmalya Mandal (University of Warwick)\n\nAbstract: \
 nHow should we design machine learning systems when the underlying environ
 ment (e.g. data distribution) changes in response to the deployed model? I
 n the context of supervised learning\, the framework of performative predi
 ction provides game-theoretic solution concepts that a learner can optimiz
 e in the presence of decision-dependent distributions. In this talk\, I wi
 ll provide an overview of our work to model such “performativity” in t
 he context of reinforcement learning. In particular\, I will describe how 
 to reach a stable policy in a setting where the underlying MDP reacts to t
 he deployed policy. I will end with some open questions\, and if time perm
 its\, some of our recent works on reinforcement learning with human feedb
 ack.\nShort Bio:\nDebmalya Mandal is an assistant professor at the Univers
 ity of Warwick\, UK. He completed his PhD from Harvard University and was
  subsequently a postdoc at Columbia University and Max Planck Institute.
  He is broadly interested in problems at the interface of machine learni
 ng and multi-agent systems.\n
URL:https://www.tcs.tifr.res.in/web/events/1468
DTSTART;TZID=Asia/Kolkata:20240903T100000
DTEND;TZID=Asia/Kolkata:20240903T110000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1454
DTSTAMP:20240826T050725Z
SUMMARY:Markov Decision Processes as Distribution Transformers: Certified P
 olicy Verification and Synthesis
DESCRIPTION:Speaker: S. Akshay (Indian Institute of Technology\, Bombay)\n\
 nAbstract: \nMarkov decision processes can be viewed as transformers of pr
 obability distributions\, giving rise to a sequence of distributions over
  MDP states. This view is useful in many applications\, e.g.\, modeling ro
 bot swarms or chemical reaction networks\, where the behavior is naturally
  interpreted as probability distributions over states. Somewhat surprising
 ly\, in this setting\, basic reachability and safety problems turn out to 
 be computationally intractable. The issue is further complicated by the q
 uestion of how much memory is allowed: even for simple examples\, policies
  for safety objectives over distributions can require infinite memory and 
 randomization.\nIn light of this\, we ask what can one do to tackle these 
 problems in theory and in practice? After taking a look at some theoretica
 l insights\, we adopt an over-approximation route to approach these questi
 ons. Inspired by the success of invariant synthesis in program verificatio
 n\, we develop a framework for inductive template-based synthesis of certi
 ficates and policies for safety and reach-avoidance objectives in MDPs. We
  show the effectiveness of our approach  as well as explore limitations a
 nd future perspectives.\n[Based on Joint Work with Krishnendu Chatterjee\,
  Tobias Meggendorfer and Djordje Zikelic at CAV'23 and IJCAI'24]\nShort Bi
 o:\nS. Akshay is a Professor in the Department of Computer Science and Eng
 ineering at IIT Bombay. His research interests span formal methods and AI 
 with a focus on automata theory\, quantitative (timed/probabilistic) verif
 ication and automated synthesis. He has given multiple tutorials on his wo
 rk in venues including Highlights 2022\, AAAI 2022 and IJCAI 2022 as well 
 as helped organize workshops on Automata\, Concurrency and Timed systems i
 n India and outside.\n
URL:https://www.tcs.tifr.res.in/web/events/1454
DTSTART;TZID=Asia/Kolkata:20240903T160000
DTEND;TZID=Asia/Kolkata:20240903T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1469
DTSTAMP:20240829T094125Z
SUMMARY:Presburger Arithmetic : Quantifier Elimination and Some Application
 s
DESCRIPTION:Speaker: Khushraj Madnani (Max Planck Institute for Software Sy
 stems\, Germany)\n\nAbstract: \nIn this talk\, we revisit the fundamental 
 problem of quantifier elimination in Existential Presburger Arithmetic. As
  one of the main highlights\, we challenge the long-standing claim that el
 iminating a block of existentially quantified variables necessarily requir
 es doubly exponential time. Our recent work refutes this by introducing a 
 novel procedure which accomplishes quantifier elimination in singly expone
 ntial time. The core of our approach is a small model property for paramet
 ric integer programming\, which extends the seminal results of von zur Gat
 hen and Sieveking on small integer points within convex polytopes. Additio
 nally\, if time permits\, I will discuss a compelling application of Presb
 urger Arithmetic in proving a dichotomy related to the reachability proble
 m for counter machines with infrequent reversals. By analyzing the growth 
 of small solutions for iterations of Presburger-definable constraints\, we
  show that any counter machine falls into one of two categories: (i) the n
 umber of reversals is uniformly bounded by a constant across all runs\, or
  (ii) the number of reversals grows at least logarithmically with the leng
 th of the run. Moreover\, reachability is undecidable for counter machines
  where the number of reversals grows logarithmically. This result indicate
 s that\, vis-à-vis counter machines\, classical reversal bounding encompa
 sses all the decidable cases within the broader framework of infrequent re
 versals.\nShort Bio:\nKhushraj Madnani is a postdoctoral researcher at the
  Max-Planck Institute for Software Systems in Kaiserslautern\, Germany\, 
  associated with the Rigorous Software Engineering group and the Models o
 f Computation group. His research interests is boradly within the domain o
 f formal verification of infinite-state systems\, focusing primarily on (1
 ) automata and logics for timed systems\, (2) formal logics and models of 
 computation\, and (3) network controlled cyber physical systems. Khushraj 
 completed his Master's and Ph.D. in Computer Science and Engineering at th
 e Indian Institute of Technology (IIT) Bombay\, Mumbai\, India\, under the
  guidance of Prof. S. Krishna and Prof. Paritosh K. Pandya where he defend
 ed his thesis titled "On Decidable Extensions of Metric Temporal Logic". 
 Before joining the Max-Planck Institute\, Khushraj was a postdoctoral rese
 archer at the Delft Center for Systems and Control (DCSC) within the Facul
 ty of Mechanical Engineering at Delft University of Technology\, The Nethe
 rlands. He also served as a visiting postdoctoral fellow at the Tata Insti
 tute of Fundamental Research (TIFR) in Mumbai\, India.\n
URL:https://www.tcs.tifr.res.in/web/events/1469
DTSTART;TZID=Asia/Kolkata:20240905T113000
DTEND;TZID=Asia/Kolkata:20240905T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1473
DTSTAMP:20240904T102442Z
SUMMARY:An introduction to fairness in reinforcement learning.
DESCRIPTION:Speaker: Vishakha Patil (Indian Institute of Science\, Bangalor
 e)\n\nAbstract: \nIn a series of three talks\, we present an overview of w
 ork in bandit optimization\, including stochastic and adversarial bandits\
 , and will focus on variants of multi-armed bandits where fairness is an a
 dditional constraint. In Fair-MAB\, for example\, in addition to the objec
 tive of maximizing the sum of expected rewards\, the algorithm also needs 
 to ensure that at any time\, each arm is pulled at least a pre-specified f
 raction of times. We investigate the interplay between learning and fairne
 ss in such settings\, and also investigate the cost of fairness.\nShort Bi
 o:\nVishakha Patil works in online learning and optimization\, game theory
 \, and mechanism design. She completed her PhD from IISc\, supported by a 
 Google Fellowship and a CII-SERB PMRF. She has also been a Heidelberg Laur
 eate Forum Young Researcher\, and her MTech thesis received an Honourable 
 Mention for the Best Thesis Award at CSA\, IISc.\n
URL:https://www.tcs.tifr.res.in/web/events/1473
DTSTART;TZID=Asia/Kolkata:20240905T140000
DTEND;TZID=Asia/Kolkata:20240905T150000
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1474
DTSTAMP:20240906T083224Z
SUMMARY:Space-width trade-offs for Resolution
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nWe
  consider two natural measures associated with a Resolution refutation*: i
 ts width (the widest clause appearing in the refutation) and its space (th
 e minimum amount of memory necessary to verify its correctness). A natural
  question to ask is the following: can we optimise both parameters at once
 ? In other words\, can we find a resolution refutation whose space and wid
 th are both close to the minimum possible value?I shall exhibit a negative
  result in this direction: there exists an unsatisfiable CNF which has a r
 efutation with constant space and a refutation with constant width\, but m
 aking one parameter small necessarily causes a blowup in the other paramet
 er.I shall be following this paper: https://dl.acm.org/doi/10.1145/509907
 .509975*PS: Don't worry if you don't know the definition of Resolution ref
 utation.\n
URL:https://www.tcs.tifr.res.in/web/events/1474
DTSTART;TZID=Asia/Kolkata:20240906T160000
DTEND;TZID=Asia/Kolkata:20240906T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1466
DTSTAMP:20240830T060930Z
SUMMARY:Fast Algorithms and Data Structures for Regression
DESCRIPTION:Speaker: Deeksha Adil (Institute for Theoretical Studies in ETH
  Zurich)\n\nAbstract: \n In this talk I will present state-of-the-art alg
 orithms for $\\ell_{\\infty}$-norm regression. Our algorithms involve new 
 techniques which combine acceleration algorithms with advanced data struct
 ures. In order to\ndo so\, we propose a novel acceleration scheme for mult
 iplicative weight update algorithms that exhibits stabiliy and robustne
 ss\, which are required for the efficient implementations of the inverse m
 aintenance data structures. Our work is the first to use acceleration and 
 inverse maintenance together efficiently\, finally making the two most imp
 ortant building blocks of modern structured convex optimization compatible
 .\nShort Bio:\nDeeksha Adil has been a Junior Fellow at the Institute for 
 Theoretical Studies at ETH Zurich since January 2023. She focuses on desig
 ning fast algorithms with provable guarantees for problems in optimization
 \, machine learning\, and theoretical computer science. She completed a Ph
 .D. at the University of Toronto under the supervision of Sushant Sachdeva
  in August 2022 after which she was visiting the University of Michigan in
  the Fall of 2022. Prior to that\, she earned a BS-MS in mathematics from 
 the Indian Institute of Science Education and Research\, Pune\, in 2017.\n
URL:https://www.tcs.tifr.res.in/web/events/1466
DTSTART;TZID=Asia/Kolkata:20240909T160000
DTEND;TZID=Asia/Kolkata:20240909T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1429
DTSTAMP:20240910T040613Z
SUMMARY:Fusing AI and Formal Methods for Automated Synthesis
DESCRIPTION:Speaker: Priyanka Golia (IIT\, Delhi)\n\nAbstract: \nWe entrust
  large parts of our daily lives to computer systems\, which are becoming i
 ncreasingly more complex. Developing scalable yet trustworthy techniques f
 or designing and verifying such systems is an important problem. In this t
 alk\, our focus will be on automated synthesis\,  a technique that uses f
 ormal specifications to automatically generate systems (such as functions\
 , programs\, or circuits) that provably satisfy the requirements of the sp
 ecification.  \nWe will introduce a state-of-the-art functional synthesis
  algorithm that leverages artificial intelligence to provide an initial gu
 ess for the system and then uses formal methods to repair and verify the g
 uess to synthesize a system that is correct by construction. We will concl
 ude by exploring the potential for combining AI and formal methods to addr
 ess real-world scenarios.\n \nShort Bio:\nPriyanka Golia is an Assistant 
 Professor in the Computer Science and Engineering Department at Indian Ins
 titute of Technology Delhi. Prior to that\, She was faculty at CISPA Helmh
 oltz Center for Information Security\, Germany. Her research interests lie
  at the intersection of formal methods and artificial intelligence. In par
 ticular\, her work so far has focused on designing scalable automated synt
 hesis and testing techniques. Her work has been awarded Best Paper Nominat
 ion at ICCAD-21\, Best Paper Candidate at DATE-23\, Invited for FMSD speci
 al issues. She was named one of the EECS Rising Stars in 2022.\n
URL:https://www.tcs.tifr.res.in/web/events/1429
DTSTART;TZID=Asia/Kolkata:20240910T160000
DTEND;TZID=Asia/Kolkata:20240910T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1480
DTSTAMP:20240913T090221Z
SUMMARY:Revisiting Tree Canonization using Polynomials.
DESCRIPTION:Speaker: Shanthanu  Suresh Rai (TIFR)\n\nAbstract: \n\nTree Iso
 morphism problem: Given two trees $T_1$ and $T_2$\, is $T_1$ isomorphic to
  $T_2$?\nOver three decades ago\, Lindell devised a deterministic logspace
  algorithm for the Tree Isomorphism problem. At a high level\, the algorit
 hm associates each tree with a unique string\, such that trees are isomorp
 hic precisely when their associated strings are identical.\nIn this talk\,
  I will present a conceptually simpler deterministic log-space algorithm f
 or the same problem\, avoiding the delicate case analysis and complex recu
 rsion in Lindell's algorithm. The algorithm will associate each tree with 
 a unique irreducible polynomial over the rationals. The irreducible polyno
 mials will be constructed using the Eisenstein's criterion for irreducibil
 ity.\nLink to the paper: https://www.arxiv.org/abs/2408.10338\n
URL:https://www.tcs.tifr.res.in/web/events/1480
DTSTART;TZID=Asia/Kolkata:20240913T160000
DTEND;TZID=Asia/Kolkata:20240913T170000
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1462
DTSTAMP:20240830T044707Z
SUMMARY:On the composition question for randomized query complexity.
DESCRIPTION:Speaker: Swagato Sanyal (Indian Institute of Technology\, Khara
 gpur)\n\nAbstract: \nA query algorithm (also known as a decision tree) tha
 t computes a Boolean function f on n variables\, queries various bits of a
 n input to f\, possibly in an adaptive fashion and using randomness. It ev
 entually produces a bit as an output\, which is supposed to equal the valu
 e of f on that input with high probability. The complexity measure of such
  an algorithm is the number of queries that it makes in the worst case. Th
 is talk considers the query complexity of a class of Boolean function call
 ed 'composed functions'. Composition of two Boolean functions f and g is\,
  informally speaking\, the Boolean function (say h) obtained by successive
  applications of g and f. The composition question\, instantiated for quer
 y complexity\, asks whether there exists a query algorithm that computes h
  that is significantly more efficient than what the definition of h sugges
 ts: first compute g and then compute f. The question has been the centre o
 f a lot of research\, and stands open to this day. In this work we present
  some results in relation to this question. The talk is based on a work th
 at was accepted to STACS 2024.\nShort Bio:\nSwagato Sanyal is an Assistant
  Professor at the Department of Computer Science and Engineering\, IIT Kha
 ragpur. Prior to this\, he was a post-doctoral research fellow at NTU and 
 NUS\, Singapore. He obtained is PhD degree from STCS\, TIFR in 2017. He is
  interested broadly in computational complexity theory\, and more specific
 ally in query and communication complexity and Boolean function analysis.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1462
DTSTART;TZID=Asia/Kolkata:20240917T160000
DTEND;TZID=Asia/Kolkata:20240917T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1481
DTSTAMP:20240920T043929Z
SUMMARY:Robust Hypothesis Testing with a Relative Entropy Tolerance
DESCRIPTION:Speaker: Malhar Ajit  Managoli (TIFR)\n\nAbstract: \nThe classi
 cal hypothesis testing problem involves\, given n samples\, to decide whet
 her they were sampled from a distribution p or distribution q. Here we con
 sider the case when the actual distributions p and q are unknown\; it is o
 nly known p is close to p_0 and q to q_0 (in KL divergence sense). We will
  find the optimal test\, optimal probability of error and the worst case d
 istribution\, for certain types of p_0\,q_0.\nBased on a paper with the sa
 me title by Bernard Levy.\n
URL:https://www.tcs.tifr.res.in/web/events/1481
DTSTART;TZID=Asia/Kolkata:20240920T160000
DTEND;TZID=Asia/Kolkata:20240920T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1432
DTSTAMP:20240905T080101Z
SUMMARY:Polynomial Time Algorithms for Integer Programming and Unbounded Su
 bset Sum in the Total Regime
DESCRIPTION:Speaker: Divesh Aggarwal (National University of Singapore (NUS
 ))\n\nAbstract: \nThe Unbounded Subset Sum (USS) problem is an NP-hard com
 putational problem where the goal is to decide whether there is a positive
  integer combination of numbers a1\,...\,an that is equal to b. The proble
 m can be solved in pseudopolynomial time\, while there are specialized ca
 ses\, such as when b exceeds the Frobenius number of a1\,...\,an\, for whi
 ch a solution is guaranteed to exist. \n \nIn this talk\, I will conside
 r the search version of this problem\, where the goal is to find the solut
 ion. explores the concept of totality in USS. The challenge in this setti
 ng is to actually find a solution\, even though we know its existence is g
 uaranteed. We focus on the instances of USS where solutions are guaranteed
  for large b. I will show that if b is slightly larger than the Frobenius 
 number\, then a solution can be found in polynomial time. We then show ho
 w our results extend to Integer Programming with Equalities (ILPE)\, highl
 ighting conditions under which ILPE becomes total. We investigate the diag
 onal Frobenius number\, which is the appropriate generalization of the Fro
 benius number to this context. In this setting\, we give a polynomial-time
  algorithm to find a solution of ILPE. The bound obtained from our algorit
 hmic procedure for finding a solution almost matches the recent existentia
 l bound of Bach\, Eisenbrand\, Rothvoss\, and Weismantel (2024).\n \nThis
  talk is based on joint work with Antoine Joux\, Miklos Santha\, and Karol
  Wegrzycki. \nShort Bio:\nDivesh Aggarwal is an Associate Professor in th
 e Department of Computer Science and a Principal Investigator at the Centr
 e for Quantum Technologies at the National University of Singapore. He ear
 ned his PhD from ETH Zurich\, where he focused on the theoretical foundati
 ons of cryptography. His research spans lattice-based cryptography\, pseud
 orandomness\, computational complexity\, and coding theory. He has made si
 gnificant contributions to the field\, including developing some of the fa
 stest known algorithms for lattice problems and advancing the understandin
 g of their computational hardness. His work also includes pioneering const
 ructions in non-malleable codes and extractors\, which play a crucial role
  in modern cryptographic protocols. In recognition of his innovative resea
 rch\, he was awarded the NRF Investigatorship in 2024\, a prestigious hono
 r granted to leading scientists in Singapore to support high-impact\, risk
 -taking research\n
URL:https://www.tcs.tifr.res.in/web/events/1432
DTSTART;TZID=Asia/Kolkata:20240924T160000
DTEND;TZID=Asia/Kolkata:20240924T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1482
DTSTAMP:20240926T092103Z
SUMMARY:Zero Knowledge Proofs using 'MPC in the head'
DESCRIPTION:Speaker: Ratnakar Medepalli (TIFR)\n\nAbstract: \nIn the settin
 g of Secure Multiparty Computation (MPC)\, n players jointly compute a fun
 ction that takes n inputs where the i-th input is held by the i-th party s
 uch that by the end of the execution\, nothing is revealed of the local in
 puts beyond the function output. Some of the seminal works in MPC such as 
 the GMW protocol (by Goldreich\, Micali and Wigderson) make use of Zero Kn
 owledge Proofs (ZKP)\, which allow a prover to convince a verifier of the 
 truth of a statement in such a manner that the proof reveals nothing beyon
 d the validity of the statement.In their work\, Ishai\, Kushilevitz\, Ostr
 ovsky and Sahai described how to construct Zero Knowledge Proofs for langu
 ages in NP from MPC protocols. This work is of particular interest because
  it kickstarted the 'MPC in the head' paradigm\, which was subsequently us
 ed to obtain a host of round-optimal black-box constructions. In this talk
 \, we will see constructions of ZKPs from MPC\, and if time permits\, we w
 ill see certain applications obtained by instantiating the MPC protocols i
 n the constructions.Reference: https://web.cs.ucla.edu/~rafail/PUBLIC/77.
 pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1482
DTSTART;TZID=Asia/Kolkata:20240927T160000
DTEND;TZID=Asia/Kolkata:20240927T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1464
DTSTAMP:20240920T094526Z
SUMMARY:Community Mode Estimation
DESCRIPTION:Speaker: Jayakrishnan Nair (Indian Institute of Technology\, Bo
 mbay)\n\nAbstract: \nWe discuss the problem of estimating the largest comm
 unity (a.k.a.\, mode) in a population composed of multiple disjoint commun
 ities. This estimation is performed in a fixed confidence (PAC) setting vi
 a sequential sampling of individuals with replacement. We consider two sam
 pling models: (i) an identityless model\, wherein only the community of ea
 ch sampled individual is revealed\, and (ii) an identity-based model\, whe
 rein the learner is able to discern whether or not each sampled individual
  has been sampled before\, in addition to the community of that individual
 . Our results\, which are structurally similar to those available for mult
 i-armed bandits in the PAC setting\, highlight the value of identity estim
 ation in the context of mode estimation.This talk is based on joint work w
 ith Meera Pai and Nikhil Karamchandani.\nShort Bio: Jayakrishnan Nair is a
 n Associate Professor in the department of Electrical Engineering at IIT B
 ombay. His research focuses on modeling\, performance evaluation\, and des
 ign issues in online learning\, queueing systems and communication network
 s\, drawing on tools from stochastic modelling\, queueing theory\, game th
 eory\, optimization\, and control theory.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1464
DTSTART;TZID=Asia/Kolkata:20241001T160000
DTEND;TZID=Asia/Kolkata:20241001T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1475
DTSTAMP:20241007T052734Z
SUMMARY:On the Computability of Competitive Equilibrium with Bads
DESCRIPTION:Speaker: Ruta Mehta (University of Illinois at Urbana-Champaign
 )\n\nAbstract: \nCompetitive equilibrium is arguably one of the most funda
 mental solution concepts within Economics with applications in diverse dom
 ains such as ensuring fair and efficient allocation of scarce resources. 
 The existence and computability of CE have been extensively studied when 
 all items are disposable goods. The problem is less explored when some are
  non-disposable chores (bads)\, despite being equally relevant\, for examp
 le\, the various labor markets. In this talk\, I will discuss recent algor
 ithmic advances in the computation of CE when the item set includes chores
 .Surprisingly\, this problem stands in sharp contrast to the goods-only ca
 se\, even under linear (additive) utility functions: for the case of goods
 \, the CE set is known to be a convex set\, while with chores\, it may be 
 non-convex and disconnected. I will discuss how to handle this non-convexi
 ty through new (continuous) optimization methods\, and via a novel non-con
 vex formulation\, leading to FPTASs. These methods may be of independent i
 nterest for finding local optima of certain classes of non-convex programs
 .Based on joint works with Shant Boodaghians\, Bhaskar Ray Chaudhury\, Chr
 istian Kroer\, and Tianlong Nan.\nShort Bio: Ruta Mehta is an Associate Pr
 ofessor of Computer Science at the University of Illinois at Urbana-Champa
 ign. Her research interests lie in theoretical computer science and its in
 terface with economics\, games theory\, fair division\, and learning. Prio
 r to joining UIUC\, she was a postdoctoral fellow at the Simons Institute\
 , and at the College of Computing\, Georgia Tech advised by Prof. Vijay Va
 zirani. She did her Ph.D. at the Indian Institute of Technology\, Bombay\,
  India\, under Prof. Milind Sohoni and Prof. Bharat Adsul. She serves on t
 he editorial boards of Math. of Operations Research (MOR) and Algorithmica
 . For her research\, she has received the NSF CAREER Award\, the Simons-Be
 rkeley Research Fellowship\, and the Best Postdoctoral Researcher Award (g
 iven by CoC@GT). Her Ph.D. thesis won the ACM India Doctoral Dissertation 
 Award and the IIT-Bombay Excellence in Ph.D. Thesis Award.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1475
DTSTART;TZID=Asia/Kolkata:20241011T113000
DTEND;TZID=Asia/Kolkata:20241011T130000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1487
DTSTAMP:20241010T085600Z
SUMMARY:Recent bounds on 3-query LCCs
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR)\n\nAbstract: \n3-query locally
  correctable codes are codes where any particular location of a corrupted 
 word can be corrected with high probability by looking at just three other
  locations. A sequence of recent works has tried to find the correct relat
 ionship between a 3-query LCC's block length and its dimension. We will lo
 ok at the proof of Alrabiah and Guruswami's near-optimal result. Though it
  needs the code to be binary and linear\, it is a nice short proof that pr
 oceeds via rainbow cycles in graphs.\nPaper link: https://arxiv.org/abs/2
 404.05864\n
URL:https://www.tcs.tifr.res.in/web/events/1487
DTSTART;TZID=Asia/Kolkata:20241011T160000
DTEND;TZID=Asia/Kolkata:20241011T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1483
DTSTAMP:20241003T111358Z
SUMMARY:Flexible list colorings
DESCRIPTION:Speaker: Rogers Mathew (IIT Hyderabad)\n\nAbstract: \nIn classi
 cal vertex coloring we wish to color the vertices of a graph G with up to 
 m colors from [m] so that adjacent vertices receive different colors\, a s
 o-called 'proper m-coloring'. List coloring is a well-known variation of c
 lassical vertex coloring that was introduced independently by Vizing and E
 rdos\, Rubin\, and Taylor in the 1970s. For list coloring\, we associate a
  'list assignment' L with a graph G such that each vertex v in G is assign
 ed a list of colors L(v) (we say L is a list assignment for G). An 'L-colo
 ring' of G is a function f with domain V(G) such that f(v) is a member of 
 L(v) for every vertex v in G. We say that G is 'L-colorable' if there exis
 ts a proper L-coloring of G: an L-coloring where adjacent vertices receive
  different colors. A list assignment L for G is called a 'k-assignment' if
  |L(v)|=k for each vertex v in G. We say G is 'k-choosable' or 'k-list col
 orable' if G is L-colorable whenever L is a k-assignment for G. The 'list 
 chromatic number' of G is the smallest k such that G is k-choosable.  \n
  \nFlexible list coloring was introduced by [Dvorak\, Norin\, and Postle
 \, 2019] in order to address a situation in list coloring where we still s
 eek a proper list coloring\, but a preferred color is given for some subse
 t of vertices and we wish to color as many vertices in this subset with it
 s preferred colored as possible\, a flexible version of the classical pr
 ecoloring extension problem. In this talk\, we explore the notion of flexi
 ble list colorings. We describe easy-to-follow proofs of two general resu
 lts and pose several open questions. \n \nThis talk is based on a joint 
 work with Hemanshu Kaul\, Jeffrey Mudrock\, and Michael Pelsmajer. \n \n
 Short Bio: Rogers Mathew is an associate professor in the Department of Co
 mputer Science and Engineering\, IIT Hyderabad. He works in graphs theory\
 , combinatorics\, and graph algorithms. \n
URL:https://www.tcs.tifr.res.in/web/events/1483
DTSTART;TZID=Asia/Kolkata:20241015T160000
DTEND;TZID=Asia/Kolkata:20241015T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1488
DTSTAMP:20241018T044435Z
SUMMARY:LLL Algorithm
DESCRIPTION:Speaker: Koduri Choudary (TIFR)\n\nAbstract: \nThe Shortest Vec
 tor Problem SVP (closest point to origin in a lattice of finite basis) is 
 considered to be hard. The LLL algorithm\, (developed by A.K. Lenstra\, H.
 W. Lenstra Jr.\, and L. Lovasz) gives an approximate solution to the SVP i
 n polynomial time on the input size i.e. description of lattice basis with
  an approximation factor (4/3)^(n/2) where n is the dimension of the latti
 ce.\nThis algorithm is a generalisation of the SVP algorithm given by Gaus
 s in 1801 for 2 dimensions.\nPaper:https://www.researchgate.net/publicatio
 n/50863306_Factoring_Polynomials_with_Rational_Coefficients\n
URL:https://www.tcs.tifr.res.in/web/events/1488
DTSTART;TZID=Asia/Kolkata:20241018T160000
DTEND;TZID=Asia/Kolkata:20241018T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1479
DTSTAMP:20240912T090252Z
SUMMARY:Transfer Q*: Principled Decoding for LLM Alignment
DESCRIPTION:Speaker: Amrit Singh Bedi (University of Central Florida)\n\nAb
 stract: \nTraditional fine-tuning of foundation models is computationally 
 heavy\, involving updates to billions of parameters. A promising alternati
 ve\, alignment via decoding\, adjusts the response distribution directly 
 without model updates to maximize a target reward r\, thus providing a lig
 htweight and adaptable framework for alignment. However\, principled deco
 ding methods rely on oracle access to an optimal Q-function (Q*)\, which 
 is often unavailable in practice. We propose Transfer Q*\, which implicitl
 y estimates the optimal value function for a target reward through a basel
 ine model aligned with a baseline reward rBL (which can be different from 
 the target reward). Our approach significantly reduces the sub-optimality 
 gap observed in prior SoTA methods and demonstrates superior empirical per
 formance across key metrics such as coherence\, diversity\, and quality in
  extensive tests on several synthetic and real datasets.\nShort Bio:\nAmri
 t Singh Bedi is an assistant professor in the Computer Science department 
 at the University of Central Florida\, Fl\, USA. Before that\, He was a r
 esearch assistant professor in the Computer Science Department at the Uni
 versity of Maryland\, College Park\, MD\, USA. He obtained his Ph.D. in El
 ectrical Engineering from IIT Kanpur\, Kanpur\, India\, in 2018. Following
  his doctoral studies\, he worked as a Research Associate within the Compu
 tational and Information Sciences Directorate at the US Army Research Labo
 ratory (ARL) in Adelphi\, MD\, USA\, from 2019 to 2022. His research inter
 ests lie in artificial intelligence (AI) for autonomous systems\, with spe
 cific emphasis on scalable & sample-efficient learning algorithms. Current
 ly\, he is working on the problem of AI alignment in language models.  Hi
 s paper was selected as one of the Best Paper Finalists at the 2017 IEEE A
 silomar Conference on Signals\, Systems\, and Computers. He received an ho
 norable mention from the IEEE Robotics and Automation Letters in 2020. He 
 was awarded the Amazon Research Award in 2022.\n
URL:https://www.tcs.tifr.res.in/web/events/1479
DTSTART;TZID=Asia/Kolkata:20241022T160000
DTEND;TZID=Asia/Kolkata:20241022T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1492
DTSTAMP:20241024T104400Z
SUMMARY:Low Degree Testing over the Reals
DESCRIPTION:Speaker: Vipul Arora (National University of Singapore)\n\nAbst
 ract: \n\nWe study the problem of testing whether a function $f: \\mathbb{
 R} ^n \\to \\mathbb{R}$ is a polynomial of degree at most $d$ in the distr
 ibution-free testing model. Here\, the distance between functions is measu
 red with respect to an unknown distribution $D$ over $\\mathbb{R}^n$ from 
 which we can draw samples. In contrast to previous work\, we do not assume
  that $D$ has finite support.\nWe design a tester that given query access 
 to $f$\, and sample access to $D$\, makes poly(d/$\\epsilon$) many queries
  to $f$\, accepts with probability $1$ if $f$ is a polynomial of degree $d
 $\, and rejects with probability at least $2/3$ if every degree-$d$ polyno
 mial $P$ disagrees with $f$ on a set of mass at least $\\epsilon$ with res
 pect to $D$.\nOur result also holds under mild assumptions when we receive
  only a polynomial number of bits of precision for each query to $f$\, or 
 when $f$ can only be queried on rational points representable using a loga
 rithmic number of bits. Along the way\, we prove a new stability theorem f
 or multivariate polynomials that may be of independent interest.\nThis is 
 a joint work with Arnab Bhattacharyya\, Esty Kelman\, Noah Fleming\, and Y
 uichi Yoshida\, and appeared in SODA'23.\nShort Bio:\nVipul is a final yea
 r PhD student at Dept of CS\, School of Computing\, National University of
  Singapore\, advised by Prof Arnab Bhattacharyya. His research interests l
 ie in Complexity Theory\, Combinatorics\, Information Theory\, and Theoret
 ical CS\, in general. His current work is focused in Property Testing\, an
 d Theoretical Machine Learning.\n
URL:https://www.tcs.tifr.res.in/web/events/1492
DTSTART;TZID=Asia/Kolkata:20241025T113000
DTEND;TZID=Asia/Kolkata:20241025T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1486
DTSTAMP:20241017T052217Z
SUMMARY:Graph Connectivity\, Partitioning\, and Fair Allocation: A Paramete
 rized Perspective
DESCRIPTION:Speaker: Susobhan Bandopadhyay (NISER Bhubaneswar)\n\nAbstract:
  \nThis talk focuses on Graph Connectivity\, Partitioning\, and their rel
 ation to the Fair Allocation problem in the parameterized complexity fram
 ework. We study the (A\,ℓ)-Path Packing problem\, a variant of Graph Co
 nnectivity\, where the goal is to maximize the number of vertex-disjoint 
 paths of length ℓ\, connecting disjoint pairs from the vertex subset A.
  Our work improves upon the hardness result established by Belmonte et al
 . [Algorithmica\, '22]\, introducing a 'Separation Lemma’\, which is an
 alogous to the 'Isolation Lemma' and could aid in proving hardness for re
 lated problems. We also explore the Shortest Non-Separating Path problem\
 , which aims to find a path between two vertices such that removing the p
 ath’s vertices does not disrupt overall graph connectivity. This is eq
 uivalent to partitioning the vertex set into two parts: one forming the s
 hortest path and the other inducing a connected component. We show that t
 he problem is intractable when parameterized by path length. In contrast\
 , its edge-based variant\, the Shortest Non-Disconnecting Path problem\, 
 is fixed-parameter tractable using matroid-based techniques.\nFurthermore
 \, we study the Constrained k-way Cut problem\, which generalizes the π-D
 eletion and k-way Cut problems. Here\, the objective is to delete edges to
  partition the graph into exactly k components\, each conforming to a spec
 ific graph family π such as trees\, bipartite\, chordal\, and bounded-deg
 ree.\nFinally\, we extend the study of the Fair Allocation problem to inco
 rporate conflicts among resources\, modeled by a conflict graph\, where re
 sources assigned to an agent maximize agent welfare and induce an independ
 ent set. This formulation is closely related to the Constrained k-way Cut 
 problem but shifts the focus from minimizing edge deletions to maximizing 
 agent welfare. Our parameterized analysis yields various tractability and 
 intractability results.\nShort Bio: Mr. Susobhan Bandopadhyay completed hi
 s B.Sc. from Ramakrishna MissionVidyamandira\, Belur Math\, Howrah\, follo
 wed by an M.Sc. in Computer Science from Ramakrishna Mission Vivekananda E
 ducational and Research Institute\, Belur Math\, Howrah. Presently\, he is
  pursuing Ph.D. at NISER Bhubaneswar under the guidance of Dr. Aritra Bani
 k. His current research focuses on parameterized algorithms\, graph algori
 thms\, and social choice theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1486
DTSTART;TZID=Asia/Kolkata:20241025T160000
DTEND;TZID=Asia/Kolkata:20241025T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1493
DTSTAMP:20241107T061825Z
SUMMARY:LocPastPDL: An expressively complete logic over Mazurkiewicz traces
  and its applications to concurrency theory
DESCRIPTION:Speaker: Shantanu Kulkarni (IIT Bombay)\n\nAbstract: \nThis tal
 k is based on our work in LiCS 2024: https://dl.acm.org/doi/abs/10.1145/3
 661814.3662110. In the talk I will first introduce the setting of concurre
 nt computation via asynchronous automata on Mazurkiewikz traces\, I will t
 hen get into the syntax and semantics of our logic “LocPastPDL”. I wil
 l talk about its applications for formal verification of concurrent system
 s and for proving a Krohn-Rhodes style decomposition theorem for regular l
 anguages over Mazurkiewicz traces. Finally if time permits I will go into 
 the proof sketch of our main result which is ‘LocPastPDL is expressively
  complete with respect to regular trace languages.’\n
URL:https://www.tcs.tifr.res.in/web/events/1493
DTSTART;TZID=Asia/Kolkata:20241108T160000
DTEND;TZID=Asia/Kolkata:20241108T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1484
DTSTAMP:20241028T045558Z
SUMMARY:Interactive proofs for primality testing of special classes of idea
 ls
DESCRIPTION:Speaker: Abhibhav Garg (University of Waterloo)\n\nAbstract: \n
 Given a set of polynomials as an algebraic circuit\, we study the problem 
 of testing if the ideal generated by these polynomials is prime. This is a
  generalisation of the problem of testing if the polynomials have a common
  solution. It is also a generalisation of the problem of testing if a poly
 nomial is absolutely irreducible. Assuming GRH\, we show that for certain 
 classes of ideals\, namely radical ideals and complete intersection ideals
 \, the problem of testing primality lies in the third level of the polynom
 ial hierarchy. This is almost optimal\, since the problems are NP-hard. Pr
 eviously\, the best known bound for these problems was PSPACE.\n \nOur me
 thod is a vast generalisation of the method used by Koiran to show that sa
 tisfiability of polynomials is in PH. We study how algebraic and geometric
  properties of ideals such as irreducibility and dimension behave under mo
 d p reduction of coefficients. We give new effective versions of classical
  results from algebraic geometry and commutative algebra that may have ind
 ependent applications.\n \nThis is joint work with Rafael Oliveira and Ni
 tin Saxena.\n \nShort Bio: Abhibhav is a fourth year PhD student at the U
 niversity of Waterloo\, advised by Rafael Oliveira. His research interests
  include algebraic complexity theory\, and computational algebraic geometr
 y and commutative algebra.\n
URL:https://www.tcs.tifr.res.in/web/events/1484
DTSTART;TZID=Asia/Kolkata:20241112T160000
DTEND;TZID=Asia/Kolkata:20241112T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1485
DTSTAMP:20241108T062250Z
SUMMARY:A High-Dimensional Goldreich-Levin Theorem
DESCRIPTION:Speaker: Silas Richelson (University of California\, Riverside)
 \n\nAbstract: \nIn this work we prove a high dimensional analogue of the b
 eloved Goldreich-Levin theorem (STOC 1989)\, which is the first local list
 -decoding algorithm. We consider the following algorithmic problem: given 
 oracle access to a function $f: Z_q^m \\rightarrow Z_q^n$ such that $\\Pr_
 {x \\sim Z_q^m} [ f(x)=Ax ] \\geq \\epsilon$ for some matrix $A \\in Z_q^{
 n \\times m}$ and $\\epsilon>0$\, recover $A$ (or a list of all such matri
 ces).\nThe original Goldreich-Levin theorem (which handles the case $n=1$ 
 above) actually handles the agreements $\\epsilon \\gt 1/q$ for any $n$. H
 ence\, we focus on tiny agreements $\\epsilon \\leq 1/q$. As stated\, this
  problem cannot be efficiently solved\, since when the list of matrices $A
 $ with good agreement with $f$ might be exponentially large. Thus we defin
 e a new notion of list-decoding\; a short list of such matrices "capturing
 '' all others.\nOur main theorem gives an algorithm which efficiently reco
 vers a (small) list\, of size $O( \\epsilon^{-1} )$\, of linear maps $A$ w
 hich satisfy: (1) each $A$ good agreement with $f$\, and (2) every linear 
 map which has good agreement with $f$\, also has good agreement with some 
 map $A$ in our list. The proof makes novel use of Fourier analysis.\nShort
  Bio:\nSilas Richelson is an Assistant Professor in the CSE Department at
  UC Riverside. His research interests are in Cryptography\, Computer Secur
 ity and Complexity Theory. He got his Ph. D. in 2014 from UCLA under the s
 upervision of Rafail Ostrovsky. From 2015 to 2017 he was a postdoctoral re
 searcher with a joint appointment at the MIT CSAIL and BU Computer Scie
 nce departments\, working with Vinod Vaikuntanathan and Ran Canetti.\n
URL:https://www.tcs.tifr.res.in/web/events/1485
DTSTART;TZID=Asia/Kolkata:20241113T100000
DTEND;TZID=Asia/Kolkata:20241113T110000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1478
DTSTAMP:20241112T094213Z
SUMMARY:Some Non-Recent Advances in Understanding the Complexity of Incenti
 ve Compatible Mechanisms
DESCRIPTION:Speaker: Shahar Dobzinski (Weizmann Institute of Science)\n\nAb
 stract: \nHow powerful are incentive-compatible polynomial-time algorithms
  compared to polynomial-time algorithms that are not necessarily incentive
 -compatible? This question stands at the heart of Algorithmic Mechanism De
 sign and has been extensively studied. This talk will take the form of a s
 urvey. We will discuss how to construct good incentive-compatible polynomi
 al time algorithms and how to prove bounds on their power.\nShort Bio: Sha
 har Dobzinski is a faculty member in the Department of Applied Mathematics
  and Computer Science at the Weizmann Institute of Science. His primary re
 search interests center on algorithmic game theory\, focusing on the inter
 section of algorithms\, incentives\, and strategic behavior in computation
 al environments.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1478
DTSTART;TZID=Asia/Kolkata:20241119T160000
DTEND;TZID=Asia/Kolkata:20241119T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1495
DTSTAMP:20241118T113152Z
SUMMARY:Minimizing Rosenthal's Potential in Monotone Congestion Games
DESCRIPTION:Speaker: Christos Tsoufis (Université Paris Dauphine)\n\nAbstr
 act: \nCongestion games are attractive because they can model many concret
 e situations where some competing entities interact through the use of som
 e shared resources\, and also because they always admit pure Nash equilibr
 ia which correspond to the local minima of a potential function. We explor
 e the problem of computing a state of minimum potential in this setting. U
 sing the maximum number of resources that a player can use at a time\, and
  the possible symmetry in the players' strategy spaces\, we settle the com
 plexity of the problem for instances having monotone (i.e.\, either non-de
 creasing or non-increasing) latency functions on their resources. The pict
 ure\, delineating polynomial and NP-hard cases is complemented with tight 
 approximation algorithms.\n \nShort Bio:\nChristos Tsoufis is a 2nd year 
 Ph.D. researcher in Computer Science at Université Paris Dauphine - PSL\,
  specializing in algorithmic game theory\, combinatorial optimization\, an
 d theoretical machine learning\, under the supervision of CNRS Researchers
  Angelo Fanelli and Laurent Gourvès. His research explores computational 
 approaches to approximate stable outcomes in games and multi-agent systems
 . Christos holds an integrated Master’s degree in Electrical and Compute
 r Engineering from the National Technical University of Athens (NTUA)\, wh
 ere he graduated with high honours.\n
URL:https://www.tcs.tifr.res.in/web/events/1495
DTSTART;TZID=Asia/Kolkata:20241122T160000
DTEND;TZID=Asia/Kolkata:20241122T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1489
DTSTAMP:20241101T090847Z
SUMMARY:Covering symmetric subsets of the hypercube with hyperplanes
DESCRIPTION:Speaker: Soumi Nandi (Indian Institute of Science (IISc)\, Beng
 aluru)\n\nAbstract: \nSuppose we want to cover all the vertices of the n d
 imensional hypercube {0\,1}$^n$  using minimum number of hyperplanes. Obs
 erve that this can be easily done using only two hyperplanes: any two hype
 rplanes containing two opposite (n-1) dimensional faces are sufficient. Mo
 reover\, no single hyperplane can cover all the vertices. Now what if we w
 ant to cover only a subset of the hypercube? For example\, suppose we want
  to cover all the vertices of {0\,1}$^n$ except one vertex\, viz. the orig
 in\, leaving out the origin as uncovered. One can observe that n hyperplan
 es are sufficient. But can we do better? The celebrated covering result by
  Alon and F$\\ddot{u}$redi shows that at least n hyperplanes are necessary
  also. We shall discuss different versions of this covering problem and we
  shall prove a generalization of Alon and F$\\ddot{u}$redi's covering resu
 lt for any symmetric subset of the hypercube.\nThis work was jointly done 
 with Arijit Ghosh\, Chandrima Kayal and S. Venkitesh.\nShort Bio: Soumi Na
 ndi is a WALMART PREDOCTORAL FELLOW at the Computer Science and Automation
  (CSA) in the Indian Institute of Science (IISc)\, Bengaluru. She submitte
 d her PhD thesis on July 31\, 2024\, as a student at the Advanced Computin
 g and Microelectronics Unit (ACMU) in the Indian Statistical Institute (IS
 I)\, Kolkata\, under the joint supervision of Sourav Chakraborty and Ariji
 t Ghosh. Her research interests broadly include Combinatorics\, Discrete G
 eometry\, and Polynomial Methods. She is currently working on two types of
  problems: Geometric Transversal Theory and covering subsets of hypercubes
  with nice geometric objects.\n
URL:https://www.tcs.tifr.res.in/web/events/1489
DTSTART;TZID=Asia/Kolkata:20241126T160000
DTEND;TZID=Asia/Kolkata:20241126T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1497
DTSTAMP:20241128T084509Z
SUMMARY:Unbounded error correcting codes
DESCRIPTION:Speaker: Eeshan Modak (TIFR)\n\nAbstract: \nEfremenko and Zamir
  introduce a variant of error correcting codes (ECC) with no predetermined
  length. An unbounded ECC with rate R and distance ε is an encoding of a
  (possibly infinite) message into a (possibly infinite) codeword\, such th
 at for every large enough k we may recover the first Rk symbols of the me
 ssage from the first k symbols of the codeword. In this talk\, we study th
 e performance of linear codes in the unbounded setting.\n \nThis talk is 
 based on this recent paper: https://arxiv.org/abs/2411.04803\n
URL:https://www.tcs.tifr.res.in/web/events/1497
DTSTART;TZID=Asia/Kolkata:20241129T160000
DTEND;TZID=Asia/Kolkata:20241129T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1477
DTSTAMP:20241122T091149Z
SUMMARY:EFX: From Agents to Types of Agents
DESCRIPTION:Speaker: Prajakta Nimbhorkar (Chennai Mathematical Institute)\n
 \nAbstract: \nWe consider the setting of fair division of indivisible item
 s and focus on the fairness notion known as "envy-freeness up to any item
  (EFX)". The input to the problem is a set of n agents and m items\, wher
 e each agent has a valuation function defined for each subset of items. T
 he goal is to partition the items among the agents so that the allocation 
 satisfies the EFX requirement. Such an allocation is called an EFX alloca
 tion. When two or more agents have the same valuation function\, the agent
 s are said to have the same "type".Existence of EFX allocations is one of 
 the central problems in fair division. The problem has turned out to be d
 ifficult\, and the existence of EFX allocations is known for only restrict
 ed cases. In particular\, EFX allocations are known to exist for three ag
 ents\, for the case when there are at most two types of agents\, and (par
 tial EFX allocations) for an arbitrary number of agents\, say n\, with at
  most n-2 items left unallocated.We make progress on these three fronts an
 d show the following:1. EFX allocations exist when agents have at most thr
 ee types.2. EFX allocations with at most k-2 items left unallocated\, when
  agents have at most k types.In this talk\, I will highlight some techniqu
 es and challenges that arise in extending the results on EFX for agents to
  EFX for types of agents.\nShort Bio:\nPrajakta Nimbhorkar is an Associate
  Professor at Chennai Mathematical Institute. Her research interests are b
 roadly in design and analysis of algorithms. She has completed her Ph.D at
  The Institute of Mathematical Sciences\, Chennai under the supervision of
  Prof. Meena Mahajan.\n
URL:https://www.tcs.tifr.res.in/web/events/1477
DTSTART;TZID=Asia/Kolkata:20241203T160000
DTEND;TZID=Asia/Kolkata:20241203T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1498
DTSTAMP:20241205T062754Z
SUMMARY:Randomness in Private Sequential Stateless Protocols
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \nA significant 
 body of work is devoted to understanding the power of randomness in privat
 e computation. In this work\, we make further progress on this by studying
  the randomness in a simple model of private computation called 'Private S
 tateless Sequential (PSS)' model. We show that the functions which can be
  computed 1-privately (i.e.\, 1 semi-honest corruption) with O(1) randomne
 ss using a speak-O(1)-times protocols are exactly those which can be compu
 ted with a constant-width read-O(1) branching programs. \nThis is a joint
  work with Varun Narayanan\, Manoj Prabhakaran and Vinod M. Prabhakaran.\n
URL:https://www.tcs.tifr.res.in/web/events/1498
DTSTART;TZID=Asia/Kolkata:20241206T160000
DTEND;TZID=Asia/Kolkata:20241206T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1494
DTSTAMP:20241125T044841Z
SUMMARY:Improved PIR Schemes using Matching Vectors and Derivatives
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Paulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nPrivate Information Retrieval (P
 IR) schemes are communication protocols with low comnunication that allow 
 a user to recover a single bit of information from a large database stored
  at multiple non-interacting servers without revealing any information abo
 ut their query to any of the servers. PIRs have long been the subject of s
 tudy with close relationships to locally decodable codes (LDCs). In this t
 alk we describe new t-server PIR schemes with communication complexity sub
 polynomial in the previously best known\, for all but finitely many t. Our
  results are based on combining the use of derivatives with "matching vect
 ors". Both ingredients are well-used in the literature on PIRs and LDCs an
 d in particular were used together in an ingenious way by Dvir and Gopi\, 
 using polynomials and derivatives over certain exotic rings\, en route to 
 their fundamental result giving the first 2-server PIR with subpolynomial 
 communication. Our result gives a matching bound for 2-server PIRs with an
  arguably simple proof\; and also leads to improvements for most other val
 ues of t\, the number of servers. (Knowledge of previous works on PIRs or
  LDCs will not be assumed in the talk.) Joint work with Fatemeh Ghasemi a
 nd  Swastik Kopparty (U. Toronto).\nShort Bio: Madhu Sudan is a Gordon Mc
 Kay Professor in the John A. Paulson School of Engineering and Applied Sci
 ences at Harvard University\, where he has been since 2015. Madhu Sudan go
 t his Bachelors degree from IIT Delhi in 1987 and his Ph.D. from U.C. Berk
 eley in 1992. Between 1992 and 2015\, Madhu Sudan worked at IBM Research (
 Research Staff Member 1992-1997)\, at MIT (Associate Professor 1997-2000\,
  Professor 2000-2011\, Fujitsu Chair Professor 2003-2011\, CSAIL Associate
  Director 2007-2009\, Adjunct Professor 2011-2015)\, and at Microsoft Rese
 arch (Principal Researcher\, 2009-2015). Madhu Sudan is a recipient of the
  Nevanlinna Prize awarded by the International Mathematical Union for outs
 tanding contributions to mathematics of computer and information science\,
  and the Infosys Foundation Prize in Mathematical Sciences\, and the IEEE 
 Hamming Medal. Madhu Sudan is a fellow of the Association for Computing Ma
 chinery\,  the Institute of Electrical and Electronics Engineers and the 
 American Mathematical Society.  He is a member of the American Academy of
  Arts and Sciences and the National Academy of Sciences. \nMadhu Sudan's r
 esearch interests revolve around mathematical studies of communication and
  computation. Specifically his research focusses on concepts of reliabilit
 y and mechanisms that are\, or can be\, used by computers to interact reli
 ably with each other. His research draws on tools from computational compl
 exity\, which studies efficiency of computation\, and many areas of mathem
 atics including algebra and probability theory.  He is best known for his
  works on probabilistic checking of proofs\, and on the design of list-dec
 oding algorithms for error-correcting codes.  His current research intere
 sts include property testing which is the study of sublinear time algorith
 ms to estimate properties of massive data\, and communication amid uncerta
 inty\, a mathematical study of the role of context in communication. \n
URL:https://www.tcs.tifr.res.in/web/events/1494
DTSTART;TZID=Asia/Kolkata:20241209T110000
DTEND;TZID=Asia/Kolkata:20241209T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1496
DTSTAMP:20241127T044149Z
SUMMARY:On the communication complexity of finding tournament winners
DESCRIPTION:Speaker: Nikhil Mande (University of Liverpool\, UK)\n\nAbstrac
 t: \nA tournament is a complete directed graph. A king in a tournament is 
 a vertex v such that every other vertex is reachable from v via a path of 
 length at most 2. It is well known that every tournament has at least one 
 king\, one of which is a maximum out-degree vertex. We study the communica
 tion complexity of these tasks in the most natural two-party distributed s
 etting\, where the edges of an underlying tournament are partitioned betwe
 en two players. I will talk about some of our recent results for n-vertex 
 tournaments:\n \n1) The deterministic communication complexity of finding
  whether a source exists is ~Theta(log^2 n).\n2) The deterministic and ran
 domized communication complexities of finding a king are Theta(n).\n3) The
  deterministic\, randomized and quantum communication complexities of find
 ing a maximum out-degree vertex are Theta(n log n)\, Theta(n log log n) an
 d ~Theta(sqrt{n})\, respectively.\n \nOur upper bounds hold for all parti
 tions of edges\, and the lower bounds for a specific partition of the edge
 s.\nI will try to present ideas of proofs of some of our upper bounds and 
 sketch the ideas that go into the lower bounds. This is based on joint wor
 k with Manaswi Paraashar\, Swagato Sanyal and Nitin Saurabh.\n \nShort Bi
 o: \nNikhil Mande is a Lecturer (Assistant Professor) in the Department o
 f Computer Science at the University of Liverpool\, a position he has held
  since January 2023. Previously\, he was a postdoctoral researcher in the
  Algorithms and Complexity Group at CWI\, hosted by Ronald de Wolf\, until
  December 2022. Prior to that\, he worked as a postdoctoral researcher in 
 the Department of Computer Science at Georgetown University\, under the me
 ntorship of Justin Thaler. Nikhil completed his doctoral studies as a res
 earch scholar in the School of Technology and Computer Science at TIFR Mum
 bai\, where he was advised by Arkadev Chattopadhyay.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1496
DTSTART;TZID=Asia/Kolkata:20241210T100000
DTEND;TZID=Asia/Kolkata:20241210T113000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1476
DTSTAMP:20241127T045431Z
SUMMARY:String constraints with subword-ordering\, context-free membership\
 , and transductions
DESCRIPTION:Speaker: Aiswarya C (Chennai Mathematical Institute)\n\nAbstrac
 t: \nWe consider a variant of string constraints given by membership const
 raints in context-free languages and subword relation between variables\, 
 or their transductions. The satisfiability problem for this variant turns 
 out to be undecidable. We consider a fragment in which the subword-order c
 onstraints do not impose any cyclic dependency between variables. We show 
 that this fragment is decidable. As an application of our result\, we sett
 le the complexity of control state reachability in acyclic lossy channel p
 ushdown systems\, which was shown to be decidable in Atig-Bouajjani-Touill
 i-08.Based on joint works with Soumodev Mal and Prakash Saivasan (LICS'22\
 , STACS'24)\nShort Bio: C. Aiswarya is an Associate Professor in Computer
  Science at Chennai Mathematical Institute\, India. She has held Invited P
 rofessor position at ENS Paris-Saclay\, France and has a Visiting Faculty 
 position at IIT Bombay India. Prior to joining CMI\, she was a post-doctor
 al researcher in Uppsala University\, Sweden. She received her PhD from EN
 S Cachan\, France. Her primary research interests are in automata theory\,
  concurrency theory and logic. She is also interested in developing theore
 tical tools for the verification of infinite state systems.\n
URL:https://www.tcs.tifr.res.in/web/events/1476
DTSTART;TZID=Asia/Kolkata:20241210T160000
DTEND;TZID=Asia/Kolkata:20241210T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1503
DTSTAMP:20241212T044452Z
SUMMARY:Polynomial time local decision
DESCRIPTION:Speaker: Soumyadeep Paul (TIFR)\n\nAbstract: \nDistributed loca
 l decision studies the power of distributed algorithms. Typically\, the pr
 ocessors are assumed to have unbounded power for local computation\, focus
 sing only on the communication between the parties. In this talk\, I will 
 be introducing the LOCAL model of distributed computing and local decision
  and some complexity classes related to them. We will then look at some co
 mplexity classes which take into account local computation as well and the
 ir connections to centralized complexity classes.\n \nThis talk is based 
 on this paper: https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.
 OPODIS.2023.27\n
URL:https://www.tcs.tifr.res.in/web/events/1503
DTSTART;TZID=Asia/Kolkata:20241212T160000
DTEND;TZID=Asia/Kolkata:20241212T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1491
DTSTAMP:20241122T091301Z
SUMMARY:Image decomposition in Fluorescence Microscopy: A posterior samplin
 g based approach
DESCRIPTION:Speaker: Ashesh Ashesh (Computational Biology Research Centre\,
  Human Technopole)\n\nAbstract: \nFluorescence microscopy\, a key driver f
 or progress in the life sciences\, faces limitations due to the microscope
 ’s optics\, fluorophore chemistry\, and photon exposure limits\, necessi
 tating trade-offs in imaging speed\, resolution\, and depth. In my talk\, 
 I will discuss the two deep-learning based computational multiplexing (ima
 ge decomposition) techniques I developed during my PhD that enhanced the i
 maging of multiple cellular structures within a single fluorescent channel
 \, allowing faster imaging and reduced photon exposure. Technically speaki
 ng\, given a superimposed image (say containing Nucleus and Tubulin)\, my 
 PhD research is to predict its constituent images separately. Early in my 
 PhD\, we found that the best results using regular deep architectures are 
 achieved when large image patches are used during training\, making GPU-me
 mory consumption the limiting factor to further improving performance. So\
 , we developed µSplit [AKDS+23]\, a novel meta-architecture that enabled 
 the memory efficient incorporation of large image-context. We used Hierarc
 hical-VAE (HVAE) and two U-Net variants as underlying architectures for µ
 Split. We modified HVAE’s ELBO loss term and adopted a KL loss formulati
 on which enabled extraction of high-frequency details. In µSplit\, we wor
 ked with noise-free data. To handle noise\, we then developed denoiSplit [
 AJ24] which performed unsupervised denoising along with supervised image s
 plitting. For this\, we incorporated Noise models\, which capture the nois
 e distribution present in the noisy images thereby making our method speci
 fic to the employed microscope’s configuration. Additionally\, we revert
 ed back to HVAE’s KL divergence formulation. denoiSplit can sample diver
 se predictions from a trained posterior and the diversity scales with the 
 aleatoric uncertainty in a given input\, allowing us to estimate the true 
 prediction errors by computing the variability between samples. During thi
 s research phase\, we observed the limitations of SSIM (Structural Similar
 ity Index Measure) in assessing model performance on microscopy data. More
  specifically\, we introduced and quantified the notion of saturation\, wh
 erein SSIM values become unreasonably high. We also observed an issue aris
 ing due to the intensity differences present in microscopy data. To this e
 nd\, we came up with MicroSSIM [ADJ24]\, an SSIM variant tailored for Micr
 oscopy data. At last\, I will try to show the utility of image translation
 /decomposition methods to biological data with a brief mention of our ongo
 ing collaboration with researchers from Google towards a related problem 
 of bleed-through removal using InDI [DM24]\, a diffusion-like iterative mo
 del.\nShort Bio: Ashesh is a last-year PhD student in the Computer Scienc
 e department at TU Dresden\, Germany. He has done all his PhD research at 
 Florian Jug’s lab\, Computational Biology Center\, Human Technopole (HT)
 \, Milan\, Italy. His PhD project is an image decomposition task of splitt
 ing a superimposed (fluorescence microscopy) image into its constituent ch
 annels\, which has already been published at reputed international confere
 nces in Computer Vision (ICCV 23 and ECCV 24). Moreover\, from several pro
 jects done by Masters\, PhDs\, and Post-doctoral fellows at Human Technopo
 le\, Ashesh's PhD project was first selected for an oral presentation and 
 later given the best oral presentation award at the HT PhD–Postdoc Sympo
 sium 2024. Previously\, Ashesh received a Dual (B.Tech+M.Tech) degree in C
 omputer Science in 2015 from IIT Delhi. He has more than 3 years of experi
 ence working in Industry\, mostly as a Data Scientist. Ashesh also worked 
 at National Taiwan University\, Taipei\, Taiwan\, as a Research Assistant 
 for about a year under Prof. Hsuan-Tien Lin. There\, he initiated research
  on multiple Computer Vision problems in the lab and got two publications.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1491
DTSTART;TZID=Asia/Kolkata:20241217T160000
DTEND;TZID=Asia/Kolkata:20241217T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1506
DTSTAMP:20241218T060403Z
SUMMARY:On Fourier analysis of sparse Boolean functions over certain Abelia
 n groups
DESCRIPTION:Speaker: Swarnalipa Datta (ISI Kolkata)\n\nAbstract: \nGiven an
  Abelian group G\, a Boolean-valued function $f: G \\to \\{-1\,+1\\}$\, is
  said to be s-sparse\, if it has at most s-many non-zero Fourier coefficie
 nts over the domain G. In a seminal paper\, Gopalan et al. in ``Testing Fo
 urier dimensionality and sparsity'' proved ``Granularity'' for Fourier coe
 fficients of Boolean valued functions over $\\mathbb{Z}_2^n$\, that have f
 ound many diverse applications in theoretical computer science and combina
 torics. They also studied structural results for Boolean functions over $\
 \mathbb{Z}_2^n$ which are approximately Fourier-sparse. In this work\, we 
 obtain structural results for approximately Fourier-sparse Boolean valued 
 functions over Abelian groups G of the form\, $G:= \\mathbb{Z}_{p_1}^{n_1}
  \\times \\cdots \\times \\mathbb{Z}_{p_t}^{n_t}$\, for distinct primes p_
 i. We also obtain a lower bound of the form $1/(m^{2}s)^{\\lceil \\varphi(
 m)/2 \\rceil}$\, on the absolute value of the smallest non-zero Fourier co
 efficient of an s-sparse function\, where $m=p_1 \\cdots p_t$\, and $\\var
 phi(m)=(p_1-1) \\cdots (p_t-1)$. We carefully apply probabilistic techniqu
 es from Gopalan et al.\, to obtain our structural results\, and use some n
 on-trivial results from algebraic number theory to get the lower bound.\nW
 e construct a family of at most s-sparse Boolean functions over $\\mathbb{
 Z}_p^n$\, where p > 2\, for arbitrarily large enough s\, where the minimum
  non-zero Fourier coefficient is o(1/s). The ``Granularity'' result of Gop
 alan et al. implies that the absolute values of non-zero Fourier coefficie
 nts of any s-sparse Boolean valued function over $\\mathbb{Z}_2^n$ are $\\
 Omega(1/s)$. So\, our result shows that one cannot expect such a lower bou
 nd for general Abelian groups.Using our new structural results on the Four
 ier coefficients of sparse functions\, we design an efficient sparsity tes
 ting algorithm for Boolean function\, which tests whether the given functi
 on is s-sparse\, or $\\epsilon$-far from any sparse Boolean function\, and
  it requires $\\mathrm{poly}((ms)^{\\varphi(m)}\,1/\\epsilon)$-many querie
 s.\nShort Bio: Swarnalipa Datta is a Senior Research Fellow in Computer S
 cience at the Indian Statistical Institute\, Kolkata\, working under the s
 upervision of Dr. Sourav Chakraborty and Dr. Arijit Ghosh on the Fourier a
 nalysis of Boolean functions. Swarnalipa completed a Bachelor's in Mathema
 tics from St. Xavier's College\, Kolkata\, and a Master's in Mathematics f
 rom the Indian Institute of Science\, Bangalore.\n
URL:https://www.tcs.tifr.res.in/web/events/1506
DTSTART;TZID=Asia/Kolkata:20241223T160000
DTEND;TZID=Asia/Kolkata:20241223T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1504
DTSTAMP:20241216T044251Z
SUMMARY:Low Degree Local Correction Over the Boolean Cube
DESCRIPTION:Speaker: Prashanth Amireddy (Harvard John A. Paulson School of 
 Engineering and Applied Sciences)\n\nAbstract: \nReed-Muller codes are an 
 important class of error-correcting codes based on evaluating low-degree p
 olynomials over a vector space. In this talk\, I will discuss our recent r
 esults about a variant of Reed-Muller codes obtained by considering low-de
 gree "group-polynomials"\, which are functions mapping {0\,1}^n to an Abel
 ian group G. Such functions naturally arise in Boolean circuit complexity 
 and learning theory\, and this work furthers the study of their coding-the
 oretic properties.\nWe will discuss our results showing that degree-d grou
 p-polynomials are locally correctable with nearly O(log n)^d queries\, for
  the fraction of errors approaching half the minimum distance of the code.
  Key to this is constructing a novel "interpolating set" for degree-d poly
 nomials\, that lies between two exponentially close parallel hyperplanes.F
 inally\, I will sketch some of the techniques used to demonstrate the list
 -decodability (in fact\, local list-correctability as well) of these codes
  for error rates approaching their minimum distance. This relies on combin
 ing results about the anti-concentration of low-degree polynomials\, the s
 unflower lemma\, and the footprint bound for counting common zeros of poly
 nomials.This is joint work with Amik Raj Behera\, Manaswi Paraashar\, Srik
 anth Srinivasan and Madhu Sudan.\nShort Bio: Prashanth is a third-year Ph
 D student at Harvard co-advised by Professors Madhu Sudan and Salil Vadhan
 . He is interested in theoretical computer science\, specifically in codin
 g theory\, pseudorandomness and complexity theory. Outside of research\, h
 e likes to run\, bike and jump.\n
URL:https://www.tcs.tifr.res.in/web/events/1504
DTSTART;TZID=Asia/Kolkata:20241224T160000
DTEND;TZID=Asia/Kolkata:20241224T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1507
DTSTAMP:20241227T050311Z
SUMMARY:Aaronson-Ambainis Conjecture Is True For Random Restrictions
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nTh
 e Aaronson-Ambainis conjecture is a very well known conjecture which state
 s the following: let P be a  degree d n-variate real polynomial P such th
 at for any x in the Boolean hypercube\, P(x) lies between 0 and 1. Then\, 
 P has a coordinate with influence >= poly(var[f]\,1/d). This conjecture ha
 s important implications to quantum query complexity.In this work\, we sho
 w that Aaronson-Ambainis conjecture is true for a non-negligible fraction 
 of random restrictions of the given function. (Based on work that will app
 ear in ITCS 2025)\n
URL:https://www.tcs.tifr.res.in/web/events/1507
DTSTART;TZID=Asia/Kolkata:20241227T103000
DTEND;TZID=Asia/Kolkata:20241227T113000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1509
DTSTAMP:20250101T115229Z
SUMMARY:Can we proper-learn ROABPs?
DESCRIPTION:Speaker: Anamay Tengse (NISER Bhubaneshwar)\n\nAbstract: \nThe 
 (proper-)learning or reconstruction problem for algebraic computation is t
 he following algorithmic task. Given access to a black box computing a pol
 ynomial F\, output a circuit computing F. It is called "proper-learning'' 
 whenever the output circuit is expected to be of the "same type'' as the p
 rovided black box. This is evidently a harder problem than polynomial iden
 tity testing\, and even designing an efficient\, randomized reconstruction
  algorithm for highly structured circuit-models is a non-trivial task.One 
 such highly structured model is that of Read-once Oblivious ABPs (ROABPs f
 or short)\, where efficient randomized reconstruction is possible\, provid
 ed the algorithm is also given "the order'' of the ROABP\; this is sometim
 es called the "grey-box'' setting. In this talk\, we will explore the miss
 ing part of the question in the title: how hard is it to find the order of
  an ROABP in the black-box setting?Based on a recent work with Vishwas Bha
 rgava\, Pranjal Dutta and Sumanta Ghosh.\n
URL:https://www.tcs.tifr.res.in/web/events/1509
DTSTART;TZID=Asia/Kolkata:20250102T110000
DTEND;TZID=Asia/Kolkata:20250102T120000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1508
DTSTAMP:20250101T034635Z
SUMMARY:Bridging Classical and Quantum Optimization: New Directions for QAO
 A and Max-Cut
DESCRIPTION:Speaker: Jai Moondra (Georgia Institute of Technology\, USA)\n\
 nAbstract: \nThe Quantum Approximate Optimization Algorithm (QAOA) is a pr
 ominent candidate for realizing quantum advantage in combinatorial optimiz
 ation problems such as Max-Cut. While its theoretical promise is exciting\
 , practical challenges such as noise\, circuit complexity\, and hardware c
 onstraints currently limit its utility on Noisy Intermediate-Scale Quantum
  (NISQ) devices. In this talk\, I will present recent advances in addressi
 ng these challenges using classical algorithmic tools.\n \nIn the first h
 alf of the talk\, I will briefly review standard QAOA for Max-Cut before i
 ntroducing custom mixers — modified circuits designed to warm-start QAOA
  by exploiting the underlying graph structure. Using warm-starts based on 
 the Goemans-Williamson SDP\, we establish approximation guarantees for the
 se mixers and demonstrate their convergence to optimal solutions. In the s
 econd half\, I will address the challenge of physically implementing QAOA 
 circuits and present the Union-of-Stars algorithm for their construction o
 n trapped-ion quantum hardware. This algorithm\, combined with classical t
 ools like graph sparsification and decomposition\, reduces overall circuit
  noise and represents the first non-trivial construction in this setting. 
 Throughout the talk\, I will highlight both theoretical and empirical resu
 lts. Based on joint work with Bryan Gard\, Swati Gupta\, Creston D. Herold
 \, Philip C. Lotshaw\, Greg Mohler\, Joel Rajakumar\, and Reuben Tate.\nSh
 ort bio: Jai Moondra is a fourth-year PhD student at the School of Compute
 r Science at Georgia Tech\, advised by Dr. Swati Gupta (MIT) and Dr. Mohit
  Singh (Georgia Tech). He finished his BTech in Computer Science and Engin
 eering from IIT Delhi in 2019. His research broadly focuses on discrete op
 timization and its applications to algorithmic fairness\, quantum computin
 g\, and machine learning.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1508
DTSTART;TZID=Asia/Kolkata:20250102T160000
DTEND;TZID=Asia/Kolkata:20250102T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1512
DTSTAMP:20250102T052021Z
SUMMARY:Algorithmic Decision-Making in the Presence of Biased Data
DESCRIPTION:Speaker: Nisheeth Vishnoi (Yale University\, US)\n\nAbstract: \
 n\nAlgorithms for optimization problems such as selection\, ranking\, and 
 classification typically assume that the inputs are what they are promised
  to be. However\, in several real-world applications of these problems\, t
 he input may contain systematic biases along socially salient attributes a
 ssociated with inputs such as race\, gender\, or political opinion. Such b
 iases can not only lead the outputs of the current algorithms to output su
 b-optimal solutions with respect to true inputs but may also adversely aff
 ect opportunities for individuals in disadvantaged socially salient groups
 . This talk will consider the question of using optimization to solve the 
 aforementioned problems in the presence of biased inputs. It will start wi
 th models of biases in inputs and discuss alternate ways to design algorit
 hms for the underlying problem that can mitigate the effects of biases by 
 taking into account knowledge about biases.\nThis talk is based on several
  joint works with Elisa Celis.\nShort Bio: Nisheeth Vishnoi is the A. Bart
 lett Giamatti Professor of Computer Science at Yale University. His resear
 ch lies at the intersection of computer science\, mathematics\, and societ
 al challenges in an increasingly algorithmic world\, with a focus on the f
 oundations and ethics of artificial intelligence. He is a Fellow of the As
 sociation for Computing Machinery (ACM) and the American Mathematical Soci
 ety (AMS)\, recognized for his contributions to theoretical computer scien
 ce and its connections to mathematics\, sciences\, and social sciences.\n
  \n \n
URL:https://www.tcs.tifr.res.in/web/events/1512
DTSTART;TZID=Asia/Kolkata:20250103T110000
DTEND;TZID=Asia/Kolkata:20250103T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1501
DTSTAMP:20241231T065603Z
SUMMARY:Learning with Structured Tensor Decompositions
DESCRIPTION:Speaker: Anand D. Sarwate (Rutgers University\, USA)\n\nAbstrac
 t: \nMany measurements or signals are multidimensional\, or tensor-valued.
  Vectorizing tensor data for statistical and machine learning tasks often 
 results in having to fit a very large number of parameters. Using tensor d
 ecompositions to model such data can give a flexible and useful modeling f
 ramework whose complexity can adapt to the amount of data available. This 
 talk will introduce classical decompositions (CP\, Tucker) as well as more
  recent ones (tensor train\, block tensor decomposition\, and low separati
 on rank) and show how they can be used to learn scalable representations f
 or tensor-valued data and make predictions from tensor-valued data. Time p
 ermitting\, we will describe applications of these ideas as part of neural
  networks and federated learning.Note: This talk does not assume the audie
 nce has prior familiarity with tensor algebra.\nShort Bio: Anand D. Sarwat
 e received his Ph.D. in electrical engineering from UC Berkeley. He is a c
 urrently an Associate Professor at Rutgers and was previously a Research A
 ssistant Professor at TTI-Chicago and a postdoc at the ITA Center at UCSD.
  His research interests include information theory\, machine learning\, si
 gnal processing\, optimization\, and privacy and security. Dr. Sarwate is 
 a Distinguished Lecturer of the IEEE Information Theory Society for 2024--
 2025 and is on the Board of Governors of the IEEE Information Theory Socie
 ty.\n
URL:https://www.tcs.tifr.res.in/web/events/1501
DTSTART;TZID=Asia/Kolkata:20250107T160000
DTEND;TZID=Asia/Kolkata:20250107T170000
LOCATION:HBA Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1511
DTSTAMP:20250101T114554Z
SUMMARY:New Approximate Max-Flow Min-Cut Theorems
DESCRIPTION:Speaker: Nikhil Kumar (University of Waterloo\, Canada)\n\nAbst
 ract: \nThe classical Max-Flow Min-Cut theorem by Ford and Fulkerson state
 s that the maximum flow between two vertices\, s and t\, in a graph is equ
 al to the minimum capacity of a set of edges whose removal disconnects s f
 rom t. This is a central theorem on which the theory of flows and cuts is 
 based and holds a central place in algorithms and discrete optimization.\n
  \nIn this talk\, I will discuss generalizations of this theorem to the m
 ulticommodity setting\, where we have multiple source-sink pairs instead o
 f one. Unfortunately\, in the multicommodity setting\, we cannot achieve a
 n exact Max-Flow Min-Cut result and must settle for approximate ones. Ther
 e is a rich and impressive body of work dedicated to proving such results\
 , driven by their importance in designing approximation algorithms. I will
  discuss recent developments in this area and highlight some key open prob
 lems.\n \nShort Bio: Nikhil Kumar is a postdoctoral researcher in the De
 partment of Combinatorics and Optimization at the University of Waterloo. 
 He earned his bachelor's\, master's\, and Ph.D. in Computer Science and En
 gineering from IIT Delhi. His broad area of interest is approximation algo
 rithms and combinatorial optimization\, with particular emphasis on networ
 k problems.\n
URL:https://www.tcs.tifr.res.in/web/events/1511
DTSTART;TZID=Asia/Kolkata:20250108T160000
DTEND;TZID=Asia/Kolkata:20250108T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1514
DTSTAMP:20250901T061310Z
SUMMARY:Fast parallel algebraic algorithms for some algebraic problems
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nOne of the earl
 iest known algorithms is Euclid's algorithm for computing the greatest com
 mon divisor of two natural numbers. This algorithm also extends to univari
 ate polynomials. The algorithm is fast\, but sequential in nature. In this
  talk\, we will see some efficient parallel algorithms (via the notion of 
 constant-depth arithmetic circuits) for some polynomial algebra problems\,
  including the GCD. An important idea here is an efficient way to go betwe
 en two well-known representations for symmetric polynomials -- the element
 ary symmetric polynomials and the power sum polynomials.The talk will be b
 ased on the paper "Constant-Depth Arithmetic Circuits for Linear Algebra P
 roblems" by Robert Andrews and Avi Wigderson.\n
URL:https://www.tcs.tifr.res.in/web/events/1514
DTSTART;TZID=Asia/Kolkata:20250110T160000
DTEND;TZID=Asia/Kolkata:20250110T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1499
DTSTAMP:20250110T044418Z
SUMMARY:Constant-Factor EFX Exists for Chores
DESCRIPTION:Speaker: Jugal Garg (Univ. of Illinois at Urbana-Champaign)\n\n
 Abstract: \nFair division is an age-old problem that deals with the alloca
 tion of items among agents with diverse preferences in a fair and efficien
 t way. It naturally arises in various real-life situations\, from interper
 sonal to international conflicts. In the discrete setting\, envy-freeness 
 up to any item (EFX) has emerged as a compelling fairness criterion\, thou
 gh its existence remains one of the most important open problems in fair d
 ivision. In this talk\, I will present recent advances in the fair allocat
 ion of indivisible chores\, focusing on the first constant-factor approxim
 ation of EFX\, achieved through the novel concept of earning-restricted co
 mpetitive equilibrium.\n \nThis talk is based on joint work with Aniket M
 urhekar and John Qin\, available at https://arxiv.org/abs/2407.03318\n \
 nShort Bio: \nJugal Garg is an associate professor of Industrial and Enter
 prise Systems Engineering and an affiliate associate professor of Siebel S
 chool of Computing and Data Science at the University of Illinois at Urban
 a-Champaign. Jugal's research studies algorithms and complexity for some o
 f the most fundamental problems in economics and computation\, with a part
 icular focus on allocation problems arising in fair division and general e
 quilibrium theory. He has received several awards for his research\, inclu
 ding the NSF CAREER Award\, the Exemplary Theory Paper Award at ACM EC 202
 0\, the INFORMS Koopman Prize 2021\, and the Dean's Award for Excellence i
 n Research 2022. \n
URL:https://www.tcs.tifr.res.in/web/events/1499
DTSTART;TZID=Asia/Kolkata:20250114T160000
DTEND;TZID=Asia/Kolkata:20250114T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1517
DTSTAMP:20250116T102554Z
SUMMARY:A simpler proof of the Chernoff bound
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR)\n\nAbstract: \nWe'll look at a
  new\, simpler proof of the Chernoff bound due to Kuszmaul. It comes with 
 a matching lower bound\, as well as some generalizations we'll cover\, tim
 e permitting. The paper is at https://arxiv.org/abs/2501.03488.\n
URL:https://www.tcs.tifr.res.in/web/events/1517
DTSTART;TZID=Asia/Kolkata:20250117T160000
DTEND;TZID=Asia/Kolkata:20250117T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1505
DTSTAMP:20250102T063254Z
SUMMARY:Polynomial Calculus sizes over the Boolean and Fourier basis are in
 comparable
DESCRIPTION:Speaker: Sasank Mouli (IIT Indore)\n\nAbstract: \nFor every n >
  0\, we show the existence of a CNF tautology over O(n^2) variables of wid
 th O(log n) such that it has a Polynomial Calculus Resolution refutation o
 ver {0\, 1} variables of size O(n^3polylog(n)) but any Polynomial Calculus
  refutation over {+1\, −1} variables requires size 2^Ω(n). This shows t
 hat Polynomial Calculus sizes over the {0\, 1} and {+1\, −1} bases are i
 ncomparable (since Tseitin tautologies show a separation in the other dir
 ection) and answers an open problem posed by Sokolov [Sok20] and Razborov.
 \n \nShort Bio: Sasank Mouli is an Assistant Professor at IIT Indore. He 
 completed his PhD at UC San Diego under the guidance of Russell Impagliazz
 o. He was briefly a postdoc at IDSIA\, Lugano\, Switzerland. \n
URL:https://www.tcs.tifr.res.in/web/events/1505
DTSTART;TZID=Asia/Kolkata:20250121T160000
DTEND;TZID=Asia/Kolkata:20250121T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1523
DTSTAMP:20250123T084533Z
SUMMARY:Roman {3}-Domination on Chain Graphs and Cographs
DESCRIPTION:Speaker: Juhi Chaudhary (TIFR)\n\nAbstract: \nA function f : 
 V(G) → {0\, 1\, 2} is a Roman dominating function on G if for every v
 ertex v with f (v) = 0\, there exists a vertex u ∈ N(v) such that
  f (u) = 2. In the literature\, numerous variants of Roman domination ex
 ist\, each corresponding to a specific defense strategy\, and Roman {3}-d
 omination is one such variant.\nA Roman {3}-dominating function on a graph
  G is a function f : V (G) → {0\, 1\, 2\, 3} having the property that fo
 r any vertex u ∈ V (G)\, if f (u) = 0\, then ∑v∈N(u)​f(v)≥3\, a
 nd if f (u) = 1\, then ∑v∈N(u)​f(v)≥2. The weight of a Roman {3}-
 dominating function f is the sum f(V(G))=∑v∈V(G)​f(v) and the mini
 mum weight of a Roman {3}-dominating function on G is called the Roman {3
 }-domination number of G and is denoted by γ_{R3}(G). \nGiven a graph G
 \, Roman {3}-domination asks to find the minimum weight of a Roman {3}-dom
 inating functionon G.  In this talk\, we will explore linear-time algorit
 hms for solving the Roman {3}-Domination problem on chain graphs and cogra
 phs.\np.s. This talk is based on the following paper   https://www.scien
 cedirect.com/science/article/abs/pii/S0166218X22003651\n
URL:https://www.tcs.tifr.res.in/web/events/1523
DTSTART;TZID=Asia/Kolkata:20250124T160000
DTEND;TZID=Asia/Kolkata:20250124T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1502
DTSTAMP:20250124T043651Z
SUMMARY:Spread regularity and applications
DESCRIPTION:Speaker: Shachar Lovett (University of California\, San Diego)\
 n\nAbstract: \nRegularity lemmas are a cornerstone of combinatorics\,
  with many applications in math and CS.  The most famous one is Szemeredi
 's regularity lemma. It shows that any graph can be partitioned into a "
 few" parts that mostly "look random". However\, there is a caveat - "few" 
 is really a huge number\, a tower of exponentials in the error parameter.M
 otivated by this\, Frieze and Kannan designed a "weak" regularity lemma\
 , sufficient for some applications\, where the number of parts is much sma
 ller\, only exponential in the error parameter. In this work\, we develop 
 an even weaker regularity lemma\, called "spread regularity"\, where th
 e number of parts is even smaller - quasi-polynomial in the error paramete
 r.I will describe our new notion of regularity and some applications:1. 
 new lower bound technique in communication complexity\, where players part
 ially share information2. new combinatorial algorithm for boolean matrix
  multiplication3. improved bounds for variants of the corners problem in a
 dditive combinatoricsBased on joint works with Amir Abboud\, Nick Fischer
 \, Michael Jaber\, Zander Kelley\, Raghu Meka and Anthony Ostuni\n \nShor
 t bio: Shachar Lovett is a professor at UC San Diego. He has a broad inter
 est in theoretical CS and combinatorics\, with emphasis on structure and r
 andomness\, coding theory\, algebraic constructions\, and additive combina
 torics. He is a recipient of an NSF career award\, a Sloan fellowship and 
 a Simons investigator award.\n
URL:https://www.tcs.tifr.res.in/web/events/1502
DTSTART;TZID=Asia/Kolkata:20250128T093000
DTEND;TZID=Asia/Kolkata:20250128T103000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1524
DTSTAMP:20250130T084500Z
SUMMARY:Bipartite Perfect Matching is in Quasi-NC
DESCRIPTION:Speaker: Soham Chatterjee (TIFR)\n\nAbstract: \nIn this talk\, 
 I will explain the Isolation lemma introduced by Mulmuley\, Vazirani\, Vaz
 irani in [MVV87] and use it to get an upper bound on the parallel complexi
 ty of bipartite perfect matching. The Isolation lemma has also been instru
 mental in the design of randomized algorithms and has contributed to sever
 al significant complexity upper bounds.\nI will present a parallel algorit
 hm for bipartite matching achieved through the derandomization of the isol
 ation lemma. This result demonstrates that the bipartite perfect matching 
 problem lies in $Quasi-NC^2$.\nThe talk will be based on the paper "Bipart
 ite Perfect Matching is in quasi-NC" by Fenner\, Gurjar and Thierauf.\n
URL:https://www.tcs.tifr.res.in/web/events/1524
DTSTART;TZID=Asia/Kolkata:20250131T160000
DTEND;TZID=Asia/Kolkata:20250131T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1510
DTSTAMP:20250203T103606Z
SUMMARY:Resolving Nondeterminism with Randomness
DESCRIPTION:Speaker: K. S. Thejaswini (Institute of Science and Technology 
 Austria (ISTA))\n\nAbstract: \nThis talk is based on joint work with Adity
 a Prakash and Thomas A. Henzinger Handling specifications given by nondet
 erministic automata for the problems of reactive synthesis or runtime veri
 fication require resolving nondeterministic choices without knowing the fu
 ture of the input word. We define classes of automata over infinite words 
 in which the nondeterminism can be resolved using a combination of memory 
 and randomness on any input word\, based solely on the prefix read so far.
 We examine two adversarial settings for providing the input word to the au
 tomaton.  In the first setting\, called ${adversarial resolvability}$\, t
 he input word is constructed letter-by-letter by an adversary\, dependent 
 on the resolver's previous decisions. In the second setting\, called ${sto
 chastic resolvability}$\, the adversary pre-commits to an infinite word an
 d reveals it letter-by-letter.  In each of the settings\, we require the 
 existence of almost-sure resolvers---resolvers that can ensure that for an
 y word in the language of the underlying nondeterministic automaton\, the 
 run constructed by that resolver is almost-surely accepting.The class of a
 utomata that are adversarially resolvable are equivalent to the well-studi
 ed class of history-deterministic automata. The latter case of stochastica
 lly resolvable automata defines a novel class. Restricting the class of re
 solvers in both settings to only memoryless stochastic resolvers further i
 ntroduces two additional new classes of automata. We show that the new cla
 sses offer interesting trade-off between succinctness\, expressivity\, and
  computational complexity\, providing a finer gradation between determinis
 tic automata and non-deterministic automata.\n \nShort Bio:\nThejaswini i
 s a post-doctoral researcher at Institute of Science and Technology Austri
 a\, working with Tom Henzinger. She did her PhD at the University of Warwi
 ck and her M.Sc and B.Sc at Chennai Mathematical Institute. She is interes
 ted in solving problems motivated in the context of verification or synthe
 sis using logic\, games\, and automata.\n
URL:https://www.tcs.tifr.res.in/web/events/1510
DTSTART;TZID=Asia/Kolkata:20250207T160000
DTEND;TZID=Asia/Kolkata:20250207T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1513
DTSTAMP:20250204T062811Z
SUMMARY:Group testing: A survey
DESCRIPTION:Speaker: Sidharth Jaggi (University of Bristol)\n\nAbstract: \n
 Group testing is the problem of inferring a (hopefully) small subset of it
 ems/individuals of interest from a large populations via pooled/group tes
 ts — test outcomes are positive if and only if the pool being tested con
 tains at least one item/individual of interest. Canonical examples include
  identifying diseased individuals in a population\, item identification in
  RFID systems\, identification of defective products in industrial systems
 \, and streaming algorithms. The theory and algorithms also offer insights
  into more general non-linear sparse inverse problems. In this talk I'll s
 urvey some classical fundamental bounds and algorithms for a variety of mo
 dels\, and present some recent results.\nShort Bio:\nSidharth (Sid) Jaggi 
 (B.Tech. IIT Bombay 2000\, M.S./Ph.D. CalTech 2006\, all in electrical eng
 ineering\, post-doctoral associate MIT 2006). He joined The Chinese Univer
 sity of Hong Kong in 2007\, and the School of Mathematics at the Universit
 y of Bristol in 2020\, where he is currently a Professor of Information an
 d Coding Theory. His research group (somewhat unwillingly) calls itself th
 e CAN-DO-IT Team (Codes\, Algorithms\, Networks: Design and Optimization f
 or Information Theory). Topics he has worked in include sparse recovery/gr
 oup-testing\, covert communication\, network coding\, and adversarial chan
 nels.\n
URL:https://www.tcs.tifr.res.in/web/events/1513
DTSTART;TZID=Asia/Kolkata:20250211T160000
DTEND;TZID=Asia/Kolkata:20250211T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1527
DTSTAMP:20250213T083759Z
SUMMARY:The Canadian traveller problem
DESCRIPTION:Speaker: Pranshu Gaba (TIFR)\n\nAbstract: \nRoads in Canada oft
 en get blocked due to excessive snowfall during blizzards. On encountering
  a road closure\, a driver needs to adapt their route on-the-fly (possibly
  involving backtracking) in order to minimise the time taken to reach thei
 r destination. This problem is known as the Canadian traveller problem. \
 nFormally\, given a graph with partially observable edge weights\, the goa
 l is to synthesise a strategy that minimises the total weight of a walk to
  the target vertex\, where an edge weight is only learnt on visiting an en
 dpoint of the edge. We look at two different variants of this problem:\n- 
 [PY91] The edge weights are chosen by an adversary. We want a strategy wit
 h the best competitive ratio\, that is\, one that minimises the ratio of t
 he total weight of the walk taken to that of the total weight of the walk 
 given by an optimal offline algorithm.\n- [KN07] The edge weights are give
 n by a probability distribution. We want a strategy that minimises the exp
 ected total weight of a walk to the destination.\nReferences:\n- [PY91](ht
 tps://www.sciencedirect.com/science/article/pii/0304397591902632) Christos
  Papadimitriou and Mihalis Yannakakis\, Shortest paths without a map (1991
 )\n- [KN07](https://people.csail.mit.edu/enikolova/papers/canadian-FINAL.p
 df) David Karger and Evdokia Nikolova\, Exact Algorithms for the Canadian 
 Traveller Problem on Paths and Trees (2007)\n
URL:https://www.tcs.tifr.res.in/web/events/1527
DTSTART;TZID=Asia/Kolkata:20250214T160000
DTEND;TZID=Asia/Kolkata:20250214T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1520
DTSTAMP:20250214T082427Z
SUMMARY:Model Checking for Real-time Systems using Generalized Timed Automa
 ta
DESCRIPTION:Speaker: Govind Rajanbabu (Uppsala University\, Sweden)\n\nAbst
 ract: \nModel checking for real-time systems is a fundamental problem in f
 ormal verification. The goal here is to check whether a system (modelled u
 sing automata) satisfies a specification (provided by a logical formula). 
 In the untimed setting\, the approach to the model-checking problem involv
 es reducing it to the reachability problem on the product of the automaton
  that models the system and the automaton corresponding to the negation of
  the logical formula. In the timed setting\, a central challenge for mode
 l-checking is the  mismatch in formalisms used for modelling systems and 
 specifications. While the behaviours of real-time systems are typically c
 aptured either using Timed automata or Automata with timers\, the predomin
 ant formalism for capturing timed specifications is either Event clock aut
 omata (ECA) or logics such as Metric Interval Temporal Logic (MITL). Furth
 er\, the translations between these different formalisms are usually quite
  expensive. Consequently\, a framework that can simultaneously capture the
  features of various timed models (clocks\, timers\, event-clocks)\, and a
 n efficient translation from timed logics to this framework would provide 
 a single-shot solution to real-time verification\, be it reachability anal
 ysis or model-checking of timed systems.We propose a new model\, called Ge
 neralized Timed Automata (GTA)\, that unifies the features of various mode
 ls such as timed automata\, event-clock automata\, and automata with timer
 s. The model comes with several powerful additional features\, and yet\, t
 he best known zone-based reachability and liveness algorithms for timed au
 tomata have been extended to the GTA model\, with the same complexity for 
 all the zone operations. Further\, we propose a logic-to-automata translat
 ion from MITL to GTA. Our translation\, which is modular\, benefits from t
 he powerful features of GTA that allow us to obtain automata with fewer st
 ates\, transitions and clocks. Since most of the formalisms used for model
 ling real-time systems are also captured by GTAs\, thanks to this translat
 ion\, the model checking problem reduces to checking reachability for GTAs
 .Based on the following works:\nA Unified Model for Real-Time Systems: Sym
 bolic Techniques and Implementation. S. Akshay\, Paul Gastin\, R. Govind\,
  Aniruddha R. Joshi and B. Srivathsan. International Conference on Compute
 r Aided Verification (CAV) 2023.\nMITL Model Checking via Generalized Time
 d Automata and a new Liveness Algorithm. S. Akshay\, Paul Gastin\, R. Govi
 nd and B. Srivathsan. International Conference on Concurrency Theory (CONC
 UR) 2024.\nShort Bio: Govind is a postdoctoral researcher in the Algorithm
 ic Verification group at the Department of Information Technology at Uppsa
 la University. Before this\, he was a postdoctoral research fellow at IIT 
 Bombay. Prior to that\, he did his Ph.D jointly at LaBRI\, Université de 
 Bordeaux and Chennai Mathematical Institute (CMI). His research is in form
 al methods\, where\, in particular\, he is interested in in automata theor
 y\, logic\, and automated synthesis\, and its applications in formal verif
 ication.\n
URL:https://www.tcs.tifr.res.in/web/events/1520
DTSTART;TZID=Asia/Kolkata:20250218T160000
DTEND;TZID=Asia/Kolkata:20250218T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1529
DTSTAMP:20250220T083032Z
SUMMARY:Robustness implies Privacy for Gaussian Mean Estimation
DESCRIPTION:Speaker: Malhar Ajit  Managoli (TIFR)\n\nAbstract: \nIn the tas
 k of parameter estimation\, robustness against corrupted samples and diffe
 rential privacy are two highly desirable properties.\nThese are also simil
 ar to each other in the sense that both require the estimator to not depen
 d too heavily on any one sample.\nIn this talk we will see how to design a
 n algorithm which is both robust and differentially private. In particular
 \, we will see a method\, known as the exponential mechanism\, which can b
 e used to turn certain types of robust algorithms into differentially priv
 ate ones.\n
URL:https://www.tcs.tifr.res.in/web/events/1529
DTSTART;TZID=Asia/Kolkata:20250221T160000
DTEND;TZID=Asia/Kolkata:20250221T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1515
DTSTAMP:20250219T045044Z
SUMMARY:On the Composition of the Complexity Measures of Boolean Functions
DESCRIPTION:Speaker: Chandrima Kayal (The Institute of Mathematical Science
 s\, Chennai)\n\nAbstract: \n\nWe can compose two Boolean functions f and g
  to obtain a new function (f o g)\, but what happens to the complexity mea
 sures? Can we express the complexity of the composed function in terms of 
 the smaller functions ( f and g) ?  Precisely\, the question is if the fo
 llowing holds:\nM(f o g) = Theta(M(f). M(g)) for some particular complexit
 y measure ( of Boolean function ) M. \nThis is one of the fundamental que
 stions in the area of Analysis of Boolean functions. Following a long line
  of work there are two big open problems in this area:\nDoes approximate d
 egree compose?\nDoes randomized query complexity compose?\nAlthough these 
 two measures are standard and well-studied\, still it is not known if they
  behave nicely under composition or not. In these studies\, we have explor
 ed two different directions and generalized the existing results\, which g
 ave an affirmative answer to both the problems for larger classes of funct
 ions. In this talk\, we will describe some of the recent results and the r
 elated open problems.Talk is based on the two following works:\n1. On the
  Composition of Randomized Query Complexity and Approximate Degree\n join
 t work with Sourav Chakraborty\, Rajat Mittal\, Manaswi Parashaar\, Swagat
 o Sanyal\, and Nitin Saurabh.\n2. Approximate degree composition for recu
 rsive functions\n joint work with Sourav Chakraborty\, Rajat Mittal\, Man
 aswi Parashaar\, and Nitin Saurabh.\n \nShort Bio:\nI am Chandrima Kayal\
 , finished my PhD from ISI Kolkata ( October'2024) under the supervision o
 f Prof. Sourav Chakraborty. Currently I am a postdoctoral fellow at IMSc w
 ith Meena Mahajan. I will be joining at IRIF with Sophie Laplante from Mar
 ch\,2025.\n
URL:https://www.tcs.tifr.res.in/web/events/1515
DTSTART;TZID=Asia/Kolkata:20250225T160000
DTEND;TZID=Asia/Kolkata:20250225T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1518
DTSTAMP:20250227T043503Z
SUMMARY:Improved Distance (Sensitivity) Oracles with Subquadratic Space
DESCRIPTION:Speaker: Keerti Choudhary (IIT Delhi)\n\nAbstract: \nA distance
  oracle for a graph $G = (V\, E)$ is a data structure that enables fast re
 trieval of approximate distances between any pair of query vertices. The o
 racle has a stretch of $(\\alpha\, \\beta)$ if the estimated distance $\\h
 at{d}(x\, y)$ for any $x\,y\\in V$ satisfies the inequality:$$d(x\, y) \\l
 eq \\hat{d}(x\, y) \\leq \\alpha \\cdot d(x\, y) + \\beta\, ~ \\forall x\,
  y \\in V.$$In the fault-tolerant model\, a related well-studied problem i
 s the distance sensitivity oracle (DSO). Here\, given a query vertex pair 
 $(s\, t)$ and a set $F$ of failed edges\, the goal is to efficiently appro
 ximate the distance between $s$ and $t$ in the graph $G - F$. Over the pas
 t two decades\, significant efforts have been made to design compact dista
 nce oracles for both static and fault-prone graphs.In this talk\, I will d
 iscuss the following results:1. The first static distance oracle with subq
 uadratic space and sublinear query time that achieves a stretch of $(1 + \
 \epsilon\, O(1))$\, where $\\epsilon > 0$ is a small constant.2. The first
  $f$-fault-tolerant DSO with subquadratic space and constant stretch\, ind
 ependent of $f$.\nShort Bio:\nKeerti Choudhary is an Assistant Professor i
 n the Department of Computer Science and Engineering at IIT Delhi. Prior t
 o this\, she held post-doctoral positions at Tel Aviv University and the W
 eizmann Institute of Science. She earned her Ph.D. in Computer Science and
  an Integrated M.Sc. in Mathematics from IIT Kanpur. Her research interest
 s lie in graph theory\, fault-tolerant structures\, and dynamic graph algo
 rithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1518
DTSTART;TZID=Asia/Kolkata:20250227T160000
DTEND;TZID=Asia/Kolkata:20250227T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1531
DTSTAMP:20250227T044058Z
SUMMARY:Black-Box Commit-and-Prove Protocols
DESCRIPTION:Speaker: Ratnakar Medepalli (TIFR)\n\nAbstract: \nCommit-and-Pr
 ove protocols allow one party to commit to a value and prove that the valu
 e satisfies a given predicate\, while ensuring that this value remains hid
 den. Such protocols are often used in the construction of MPC protocols. B
 lack-box commit-and-prove protocols are those that use the composite primi
 tives without looking at the underlying code\, and are often preferred due
  to efficiency reasons. One salient measure of the complexity of such prot
 ocols is the number of rounds of communication.\n \nIn this talk\, we wil
 l see a three-round commit-and-prove protocol by Hazay and Venkitasubraman
 iam that satisfies constant soundness and zero-knowledge. We will also see
  the construction by Khurana\, Ostrovsky and Srinivasan that boosts the so
 undness when the zero knowledge requirement is relaxed to witness-indistin
 guishability.\n \nReferences:\n \n1. On the Power of Secure Two-Party Co
 mputation\n \n2. Round Optimal Black-Box "Commit-and-Prove"\n
URL:https://www.tcs.tifr.res.in/web/events/1531
DTSTART;TZID=Asia/Kolkata:20250228T160000
DTEND;TZID=Asia/Kolkata:20250228T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1500
DTSTAMP:20250213T100844Z
SUMMARY:Regular languages over countable words
DESCRIPTION:Speaker: Sreejith A V (IIT Goa)\n\nAbstract: \nCountable words 
 are mappings from a countable linear ordering to a finite alphabet. Finite
  words and omega words are examples of countable words. In this talk\, we 
 look at the refined understanding of language-logic-expression-algebra int
 erplay over countable words.\nRegular languages are those languages (over 
 countable words) definable in monadic second order logic. However\, regula
 r languages also have multiple characterizations through expressions\, alg
 ebra etc. We will also look at some nice subclasses of regular languages 
 – like those languages definable in first order logic\, weak monadic sec
 ond order logic etc.\nShort Bio:I am a faculty in the computer science dep
 artment of IIT Goa. I did my PhD from IMSc\, Chennai. I am interested in a
 utomata theory and logic.\n
URL:https://www.tcs.tifr.res.in/web/events/1500
DTSTART;TZID=Asia/Kolkata:20250304T160000
DTEND;TZID=Asia/Kolkata:20250304T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1533
DTSTAMP:20250306T053732Z
SUMMARY:Robust and Heavy-Tailed Mean Estimation Made Simple\, via Regret Mi
 nimization
DESCRIPTION:Speaker: Santanu Das (TIFR)\n\nAbstract: \nRobust mean estimati
 on for high-dimensional data in the presence of adversarial corruption is 
 a well-studied problem in robust statistics. In this talk\, we present an 
 algorithm that tackles robust mean estimation by first reducing the proble
 m to a meta-problem\, and reformulating the original task into a framework
  that isolates the key statistical properties. Once the meta-problem is es
 tablished\, we employ a multiplicative weight update method to solve it. T
 his computationally efficient iterative approach reweights the data points
  based on their consistency with the current estimate\, effectively dimini
 shing the influence of corrupted samples\n \nThe talk is based on https:
 //arxiv.org/abs/2007.15839.\n
URL:https://www.tcs.tifr.res.in/web/events/1533
DTSTART;TZID=Asia/Kolkata:20250307T160000
DTEND;TZID=Asia/Kolkata:20250307T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1516
DTSTAMP:20250307T032906Z
SUMMARY:Hardness Condensation for Decision Tree Measures
DESCRIPTION:Speaker: Nitin Saurabh (IIT Hyderabad)\n\nAbstract: \nCan every
  Boolean function on n variables with query complexity k << n be restricte
 d to O(k) variables such that the query complexity remains $\\Omega(k)$? I
 n other words\, can query complexity be condensed by restrictions? Goos-Ne
 wman-Riazanov-Sokolov (STOC'24) studied such hardness condensation questio
 ns and showed\, among other results\, that query complexity can not be con
 densed losslessly. They asked if complexity measures like block sensitivit
 y or unambiguous certificate complexity can be condensed?\nIn this talk\, 
 we will see that a host of complexity measures\, like block sensitivity\, 
 unambiguous certificate complexity\, certificate complexity etc. cannot be
  condensed losslessly.  In the process we will improve upon the condensat
 ion result for query complexity of [GNRS'24] and also obtain some positive
  results on condensation. \nThis talk is based on a joint work with Chand
 rima Kayal (IMSc\, Chennai --> IRIF\, Paris).\nShort Bio:\nNitin Saurabh i
 s a faculty member in the CSE department at IIT Hyderabad since 2022. His 
 research interests lie broadly in theoretical computer science\, and espec
 ially in complexity theory\, Boolean function analysis\, algebraic complex
 ity\, etc. \n \n \n
URL:https://www.tcs.tifr.res.in/web/events/1516
DTSTART;TZID=Asia/Kolkata:20250311T160000
DTEND;TZID=Asia/Kolkata:20250311T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1519
DTSTAMP:20250317T091122Z
SUMMARY:Semi-Bandit Learning for Monotone Stochastic Optimization
DESCRIPTION:Speaker: Arpit Agarwal (IIT Bombay)\n\nAbstract: \nStochastic o
 ptimization is a widely used approach for optimization under uncertainty\,
  where uncertain input parameters are modeled by random variables. Exact o
 r approximation algorithms have been obtained for several fundamental prob
 lems in this area. However\, a significant limitation of this approach is 
 that it requires full knowledge of the underlying probability distribution
 s. Can we still get good (approximation) algorithms if these distributions
  are unknown\, and the algorithm needs to learn them through repeated inte
 ractions? Particularly\, can we design an online learning algorithm whose 
 performance smoothly approaches the performance of an (offline) optimal al
 gorithm which has knowledge of these distributions?In this work\, we resol
 ve this question for a large class of "monotone" stochastic problems\, by 
 providing a generic online learning algorithm with \\sqrt{T log T} regret 
 relative to the best approximation algorithm (under known distributions). 
 Importantly\, our online algorithm works in a semi-bandit setting\, where 
 in each period\, the algorithm only observes samples from the r.v.s that w
 ere actually probed. Our framework applies to several fundamental problems
  in stochastic optimization such as prophet inequality\, Pandora's box\, s
 tochastic knapsack\, stochastic matchings and stochastic submodular optimi
 zation.In this talk\, I will first introduce the multi-armed bandits frame
 work and describe the popular algorithmic principle of "optimism in the fa
 ce of uncertainty". I will then give a brief introduction to stochastic op
 timization. Finally\, I will describe our result on conversion from offlin
 e to online semi-bandit algorithms for stochastic optimization.This talk i
 s based on a FOCS'24 paper with Rohan Ghuge and Viswanath Nagarajan- http
 s://arxiv.org/pdf/2312.15427.\nShort Bio:\nArpit Agarwal is an Assistant P
 rofessor at the CSE Department at IIT Bombay. His research lies in the are
 a of machine learning (ML) and artificial intelligence (AI). His focus is 
 on human-centered AI which includes learning from human feedback\, underst
 anding AI impact on individuals and society\, and designing socially respo
 nsible AI. Prior to joining IIT Bombay\, he was a researcher at FAIR Labs 
 (Meta). Before that he was a postdoctoral fellow at the Data Science Insti
 tute at Columbia University. He completed his PhD from the CIS Department 
 at University of Pennsylvania\, and masters from CSA Department at IISc Ba
 ngalore where he was the recipient of the Computer Society of India Medal.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1519
DTSTART;TZID=Asia/Kolkata:20250318T160000
DTEND;TZID=Asia/Kolkata:20250318T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1536
DTSTAMP:20250321T043453Z
SUMMARY:Binary Interactive Codes with Erasure Resilience > 1/2
DESCRIPTION:Speaker: Bikshan Chatterjee (TIFR)\n\nAbstract: \nCoding for In
 teractive Communication" is the study of making interactive protocols resi
 lient to errors. But we can ask the following question: what if the origin
 al protocol was only sending a single message from Alice to Bob ? Can usin
 g interaction (allowing Bob to send noisy feedback) help them achieve high
 er error-resilience than what is possible with error correcting codes ?\nW
 e will see a binary interactive protocol achieving erasure resilience 6/11
  (greater than 1/2 which is the plotkin bound barrier for erasure resilien
 ce using normal error correcting codes).\n \nThe talk will be based on th
 e paper "Interactive Error Correcting Codes Over Binary Erasure Channels R
 esilient to > 1/2  Adversarial Corruption" by Meghal Gupta\, Yael Tauman 
 Kalai and Rachel Yun Zhang. \nReference: https://arxiv.org/abs/2111.04181
 .\n
URL:https://www.tcs.tifr.res.in/web/events/1536
DTSTART;TZID=Asia/Kolkata:20250321T160000
DTEND;TZID=Asia/Kolkata:20250321T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1522
DTSTAMP:20250320T085509Z
SUMMARY:Incompressible Encryption - Advanced Functionalities\, Stronger Sec
 urity and Lower Bounds
DESCRIPTION:Speaker: Venkata Koppula (IIT Delhi)\n\nAbstract: \nEncryption 
 is our go-to solution for secrecy related problems. If Alice and Bob want 
 to communicate securely\, they can encrypt their messages\, and the securi
 ty of encryption guarantees that the adversary cannot learn anything about
  the underlying message (assuming the decryption key is kept hidden). Howe
 ver\, what if the adversary also learns the decryption key? Can we offer a
 ny kind of security in such scenarios? If the adversary does not have the 
 entire ciphertext\, then we can hope for security even in such scenarios. 
 The primitive that captures such security threats is incompressible encryp
 tion. \n \nIn this talk\, I will discuss some recent advances related t
 o incompressible encryption. This includes incompressible notions of advan
 ced encryption functionalities (such as attribute-based encryption and fun
 ctional encryption)\, stronger security (which ensures security against s
 ide-channel attacks)\, and lower bounds for incompressible encryption. \n
  \nBased on joint works with Kaartik Bhushan\, Rishab Goyal\, Manoj Prabh
 akaran\, Varun Narayanan\, Mahesh Sreekumar Rajasree\, Aman Verma.\nShort 
 Bio:\nVenkata Koppula is an assistant professor in the department of compu
 ter science and engineering at IIT Delhi. He did his PhD at UT Austin\, an
 d spent his postdoctoral years at the Weizmann Institute in Israel. His re
 search interests are in Theoretical Cryptography\, including both quantum 
 and post-quantum cryptography. \n \n
URL:https://www.tcs.tifr.res.in/web/events/1522
DTSTART;TZID=Asia/Kolkata:20250325T113000
DTEND;TZID=Asia/Kolkata:20250325T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1538
DTSTAMP:20250327T045814Z
SUMMARY:On minimax optimality in the active simple hypotheses testing probl
 em.
DESCRIPTION:Speaker: Sushant Vijayan (TIFR)\n\nAbstract: \nIn this talk\, w
 e consider the following online decision making problem: Given a set of un
 certain alternatives how must one take decisions so that one minimizes the
  error probability of choosing a suboptimal alternative given a fixed samp
 le budget. This is motivated by practical applications in diverse fields l
 ike drug trials\, online advertising and sensor placement and more general
 ly in areas of online decision making where the samples cannot be generate
 d in a sequential manner and have a fixed limited budget. This problem is 
 called the Fixed Budget Best Arm identification (FB-BAI) in the Multi Arme
 d Bandit (MAB) community but has also been studied by the research communi
 ties in online decision making\, simulation\, operations research and info
 rmation theory.In Komiyama et. al (2022) an information theoretic lower bo
 und and a matching algorithm assuming access to a computationally and anal
 ytically intractable oracle was proposed. As this is a difficult problem t
 o handle in this level of generality\, we instead study a special case of 
 FB-BAI: Active Simple Hypothesis Testing (ASHT). Even in this simplified s
 etting\, optimal algorithms and their information theoretic limits are not
  well understood. In the ASHT setting\, we place Komiyama et al's bounds i
 n a game theoretic framework and show that it is the value function of a c
 ertain differential game. We show that this value function is the viscosit
 y solution to an associated Hamilton-Jacobi-Isaac(HJI) Partial Differentia
 l Equation (PDE). This PDE formulation allows us to derive new bounds on e
 rror exponents\, produce a counterexample to a conjecture of Komiyama et a
 l and create a computationally tractable $\\epsilon$-optimal algorithm whe
 n the action set (A) of the hypotheses is small. As the PDE approach is co
 mputationally difficult for moderate size A\, we use a novel link of ASHT 
 with approachability problems to propose a new approachability algorithm t
 hat is provably better than the best static algorithms. Further\, we numer
 ically observe that in certain problem instances\, the proposed algorithm 
 attains the optimal exponent.We will give a broad introduction to the prob
 lem. The technical details will be kept to a minimum to make the talk more
  accessible.Reference: Komiyama et al.: https://arxiv.org/pdf/2206.04646
 \n
URL:https://www.tcs.tifr.res.in/web/events/1538
DTSTART;TZID=Asia/Kolkata:20250328T160000
DTEND;TZID=Asia/Kolkata:20250328T170000
LOCATION:Screening in A-201 with Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1526
DTSTAMP:20250321T084041Z
SUMMARY:Greybox Learning of Languages Recognizable by Event-Recording Autom
 ata
DESCRIPTION:Speaker: Anirban Majumdar\n\nAbstract: \nIn this talk\, I will 
 present our work on active learning of timed languages recognizable by Eve
 nt-Recording Automata (ERA). Active learning is a type of model inference 
 approach to learn an unknown language by making membership and equivalence
  queries to a Teacher. In this work\, we introduce an active learning algo
 rithm\, tLSep\, for learning ERA-recognizable languages. Our framework emp
 loys a method known as grey-box learning\, which enables the learning of E
 RA with the minimum number of states. \n \nI will first introduce the ac
 tive learning framework for inferring languages. I will then introduce the
  class of timed languages recognizable by ERA. Finally\, I will describe o
 ur result on the learning of ERA-recognizable languages.\n \nThis talk is
  based on our ATVA 2024 paper with Sayan Mukherjee and Jean-François Rask
 in.\n \nShort Bio:\nAnirban Majumdar is currently visiting various resear
 ch institutes in India. Earlier he was a post-doctoral researcher in the V
 erification group at Université Libre de Bruxelles\, working with Jean-Fr
 ançois Raskin. He did his PhD from ENS Paris-Saclay under the supervision
  of Patricia Bouyer-Decitre and Nathalie Bertrand. His research interests 
 include synthesis of reactive systems\, automata learning\, distributed sy
 stems. \n
URL:https://www.tcs.tifr.res.in/web/events/1526
DTSTART;TZID=Asia/Kolkata:20250401T160000
DTEND;TZID=Asia/Kolkata:20250401T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1540
DTSTAMP:20250403T093508Z
SUMMARY:Learning Real-Time One-Counter Automata Using Polynomially Many Que
 ries
DESCRIPTION:Speaker: Prince Mathew (IIT Goa)\n\nAbstract: \nIn this talk\, 
 we introduce a novel method for active learning of deterministic real-time
  one-counter automata (DROCA). The existing techniques for learning DROCA 
 rely on observing the behaviour of the DROCA up to exponentially large cou
 nter-values. Our algorithm eliminates this need and requires only a polyno
 mial number of queries. Additionally\, our method differs from existing te
 chniques as we learn a minimal counter-synchronous DROCA\, resulting in mu
 ch smaller counter-examples on equivalence queries. Learning a minimal cou
 nter-synchronous automaton cannot be done in polynomial time unless P = NP
 \, even in the case of visibly one-counter automata. We use a SAT solver t
 o overcome this difficulty. The solver is used to compute a minimal separa
 ting DFA from a given set of positive and negative samples. We implemented
  the proposed learning algorithm and tested it on randomly generated DROCA
 . Our evaluations show that the proposed method outperforms the existing t
 echniques on the test set.\nShort Bio:\nPrince Mathew is pursuing his PhD 
 in Theoretical Computer Science under the guidance of Dr. Sreejith A.V. in
  the School of Mathematics and Computer Science at IIT Goa.\n
URL:https://www.tcs.tifr.res.in/web/events/1540
DTSTART;TZID=Asia/Kolkata:20250404T160000
DTEND;TZID=Asia/Kolkata:20250404T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1541
DTSTAMP:20250408T091523Z
SUMMARY:Corruption-Tolerant Algorithms for Generalized Linear Model
DESCRIPTION:Speaker: Debojyoti Dey (IIT Kanpur)\n\nAbstract: \nGeneralized 
 Linear Model (GLM) is a unified framework which brings Linear regression o
 ver real valued labels\, Gamma or Poisson regression over positive labels\
 , as well as Logistic regression over Binary labels under the same umbrell
 a\, and solves a Maximum Likelihood Estimation (MLE) problem to estimate t
 he model generating the data. Even unsupervised learning model such as Emp
 irical Mean Estimator is an example of maximum likelihood estimate. The ML
 E based algorithms often fail to recover the true model when a fraction of
  the observed data points are adversarially contaminated. \nIn this talk\
 , I am going to discuss our work on Robust Learning Algorithms for GLM und
 er adversarial corruptions. In this work\, we introduced a version of Expe
 ctation Maximization (EM) algorithm which exploits an adaptive variance al
 teration while solving a weighted MLE. The algorithm\, called SVAM (Sequen
 tial Variance-Altered MLE )\, offers provable model recovery guarantees su
 perior to the state-of-the-art for robust regression even when a constant 
 fraction of training labels are corrupted. The algorithm is also efficient
  in the sense that it offers linear rate of convergence to true optima. Ap
 art from linear regression\, the technique and the result extend to gamma 
 and logistic regression\, mean estimation etc. SVAM also empirically outpe
 rforms several existing problem-specific techniques for robust regression 
 and classification.\nThe talk is based upon a published article\, coauthor
 ed by Bhaskar Mukhoty and Purushottam Kar.\nShort Bio:\nDebojyoti Dey is a
  final year PhD student at IIT Kanpur. His research interest spans non-con
 vex and robust optimization\, distribution learning in Probabilistic Graph
 ical Model etc.\n
URL:https://www.tcs.tifr.res.in/web/events/1541
DTSTART;TZID=Asia/Kolkata:20250408T160000
DTEND;TZID=Asia/Kolkata:20250408T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1542
DTSTAMP:20250411T052318Z
SUMMARY:Some problems related to online bipartite matching
DESCRIPTION:Speaker: Arghya Chakraborty (TIFR)\n\nAbstract: \nSeveral real-
 world problems work in the 'online' setting where the input arrives in a s
 equential manner and decisions\, sometimes irrevocable\, need to be taken 
 without access to the future inputs. In this thesis\, we work on the onlin
 e version of two problems: bipartite matching and facility location. In th
 is synopsis\, I'll present some of the results we obtained while studying 
 the online bipartite matching problem.\n \nThe online bipartite matching 
 problem is one of most classical online algorithms studied. Several real-l
 ife problems like organ donation\, ad allocation etc can be formulated in 
 terms of online bipartite matching. In their seminal work\, Karp\, Vaziran
 i and Vazirani introduced the RANKING algorithm\, a randomized algorithm w
 hich attained a competitive ratio of (1-1/e) for the unweighted case and s
 howed that no randomized algorithm can do better. It is also known that th
 e WATERLEVEL algorithm attains a similar competitive ratio for the determi
 nistic fractional version of the unweighted  problem. A lot of work has g
 one recently towards extending these algorithms to edge-weighted settings.
  In particular\, a new sub-routine called online correlated selection (OCS
 ) was introduced to achieve competitive ratio beyond the trivial 1/2 obtai
 ned by the greedy algorithm\n \nIn this work\, we present the following r
 esults related to the online bipartite matching problem\nWe show that for 
 the degree-2 bounded case\, where every online vertex has degree at most t
 wo\, the folklore half-half algorithm achieves a competitive ratio of  0.
 717772 and more surprisingly show that this is in fact tight\, no randomiz
 ed algorithm can do any better\nWe give a new OCS subroutine which attains
  the optimal parameter of 1/4. Previous results had shown that no OCS subr
 outine (even in the fully offline setting) can achieve a parameter better 
 than 1/4.\nWe give a deterministic WATERLEVEL-based algorithm that achieve
 s a competitive ratio of (1-1/e) for the edge-weighted case. This result w
 as known before\, but to the best of our knowledge\, this presentation in 
 terms of water-level is new.\nIn the talk\, I'll describe the bipartite ma
 tching problem\, OCS problem\, a summary of known results and an overview 
 of the new algorithms that prove the above stated results.\n
URL:https://www.tcs.tifr.res.in/web/events/1542
DTSTART;TZID=Asia/Kolkata:20250411T153000
DTEND;TZID=Asia/Kolkata:20250411T163000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1544
DTSTAMP:20250411T051043Z
SUMMARY:Sampling is as easy as learning the score: theory for diffusion mod
 els with minimal data assumptions
DESCRIPTION:Speaker: Agniv Bandyopadhyay (TIFR)\n\nAbstract: \nWe will cons
 ider the problem of proving theoretical convergence guarantees for score-b
 ased generative models (SGMs)\, such as DDPMs\, which are foundational to 
 large-scale generative systems like DALL·E 2. We will prove that\, given 
 L2-accurate score estimates\, SGMs can efficiently sample from a broad cla
 ss of realistic data distributions without relying on restrictive assumpti
 ons like log-concavity or log-Sobolev-ness. The convergence rate scales po
 lynomially with problem parameters and matches the best-known complexity b
 ounds for Langevin diffusion discretization. Proving this convergence rate
  relies on a clever application of Girsanov's theorem\, which is a celebra
 ted theorem in stochastic calculus\, which we will explore during this tal
 k. \nThis talk will be based on results presented in the paper: Chen\, S
 .\, Chewi\, S.\, Li\, J.\, Li\, Y.\, Salim\, A.\, & Zhang\, A. R. (2022). 
 Sampling is as easy as learning the score: theory for diffusion models wit
 h minimal data assumptions. (https://arxiv.org/abs/2209.11215)\n
URL:https://www.tcs.tifr.res.in/web/events/1544
DTSTART;TZID=Asia/Kolkata:20250411T170000
DTEND;TZID=Asia/Kolkata:20250411T180000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1528
DTSTAMP:20250409T044556Z
SUMMARY:Geometry in Optimization: To Choose or Not to Choose
DESCRIPTION:Speaker: Sujoy Bhore (IIT Bombay)\n\nAbstract: \nGeometry lies 
 at the heart of optimization\, where the seemingly simple decision of "to 
 choose or not to choose an object" often uncovers profound insights into t
 he structure and solutions of complex problems. This geometric perspective
  has wide-ranging applications across various fields\, including machine l
 earning\, logistics\, computer graphics\, sensor networks\, and many other
 s. In this talk\, I will focus on two fundamental aspects of geometric opt
 imization problems: Packing and Independence.Consider a set of D-dimension
 al objects (each with associated profits)\, and the goal is to find the ma
 ximum profit subset that can be packed non-overlappingly into a given D-di
 mensional hypercube. This problem is known as the Geometric Knapsack Probl
 em. The packing of various kinds of objects has been extensively studied i
 n Mathematics over the centuries. Interestingly\, the problem becomes comp
 utationally intractable\, even in rather simple settings\, e.g.\, unit dis
 ks in 2D. In this talk\, I will present a polynomial time approximation sc
 heme for packing D-dimensional balls.On the other hand\, the Independent S
 et problem for a set of objects in D-dimensional space aims to find a maxi
 mum-cardinality subset of independent (i.e.\, pairwise-disjoint) objects. 
 Independent set is one of the most fundamental problems in Theoretical Com
 puter Science\, and unfortunately\, it is known to be inapproximable in th
 e most general cases. There has been extensive research on polynomial-time
  algorithms with improved approximation ratios for geometric inputs\, some
 times trading off efficiency in running times. In this talk\, I will prese
 nt near-linear time constant-factor approximation algorithms for various n
 atural families of objects\, e.g.\, rectangles\, balls\, etc.\nShort Bio:\
 nSujoy is a faculty member in the Department of Computer Science & Enginee
 ring at the Indian Institute of Technology Bombay and a visiting fellow in
  the Department of Mathematics at the London School of Economics. Previous
 ly\, he was a postdoctoral research fellow at the Faculty of Informatics\,
  TU Vienna\, and the Department of Computer Science\, ULB Brussels. He rec
 eived his Ph.D. from the Department of Computer Science\, Faculty of Natur
 al Sciences\, Ben-Gurion University\, Israel. Sujoy has been the recipient
  of the Krietman doctoral fellowship\, US-Israel BSF fellowship\, London M
 athematical Society fellowship\, and Young Faculty Award at IIT Bombay.\n
URL:https://www.tcs.tifr.res.in/web/events/1528
DTSTART;TZID=Asia/Kolkata:20250415T160000
DTEND;TZID=Asia/Kolkata:20250415T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1547
DTSTAMP:20250421T050849Z
SUMMARY:How to Construct Random Strings
DESCRIPTION:Speaker: Rahul Santhanam (University of Oxford)\n\nAbstract: \n
 We give the first complexity-theoretic evidence for explicit constructions
  of objects such as rigid matrices (in the sense of Valiant) and Ramsey gr
 aphs on n vertices that do not have cliques or independent sets of size 2l
 og(n). More generally\, we give plausible complexity assumptions under whi
 ch the Range Avoidance problem can be solved efficiently on uniform sequen
 ces of Boolean circuits - the non-uniform version was recently shown to be
  hard under standard cryptographic assumptions. As a by-product of our tec
 hniques\, we construct hitting set generators against uniform algorithms w
 ith sub-logarithmic seed length\, under plausible complexity assumptions a
 s above.\n \n(Based on joint work with Oliver Korten).\n \nShort Bio:\nR
 ahul Santhanam is Professor of Computer Science at University of Oxford\, 
 and Tutorial Fellow in Computer Science at Magdalen College. He completed 
 his PhD in Computer Science at the University of Chicago in 2005\, and aft
 er postdoctoral stints at Simon Fraser University and University of Toront
 o\, was Lecturer (2008-2013) and then Reader (2013-2015) at the University
  of Edinburgh\, before moving to Oxford. His work in mainly in computation
 al complexity theory\, with a particular interest in connections with othe
 r areas such as logic\, algorithms\, cryptography\, learning and game theo
 ry.\n
URL:https://www.tcs.tifr.res.in/web/events/1547
DTSTART;TZID=Asia/Kolkata:20250424T160000
DTEND;TZID=Asia/Kolkata:20250424T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1550
DTSTAMP:20250425T065111Z
SUMMARY:Rare events in stochastic multi-armed bandits
DESCRIPTION:Speaker: Anirban Bhattacharjee (TIFR)\n\nAbstract: \nThis synop
 sis summarizes the problems addressed in the dissertation and the main res
 ults obtained in the course of studying these problems. We examine stochas
 tic multi-armed bandit (MAB) problems in rare event regimes with emphasis 
 on Best Arm Identification (BAI) and also touch upon regret minimization.
  When arm rewards occur infrequently but are high in magnitude\, we develo
 p algorithms for BAI which are based on Poisson approximation and drastic
 ally reduce computational effort at the cost of negligible increase in sa
 mple complexity. For identifying the safest system among a given set of s
 afety-critical systems with rare failures\, we consider simulation models 
 of the systems\, and simulate from them following BAI methods. Reasonably
  accurate approximations of the lower bound on sample complexity reveal t
 hat sample complexity depends on the failure rate of the secondbest system
 \, as opposed to the best. Further\, standard regret minimization algorith
 ms are shown to perform poorly in rare-event regimes where rewards are hi
 gh-value but rarely seen\, necessitating scaled modifications that ensure
  optimality\n
URL:https://www.tcs.tifr.res.in/web/events/1550
DTSTART;TZID=Asia/Kolkata:20250425T160000
DTEND;TZID=Asia/Kolkata:20250425T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1530
DTSTAMP:20250424T051153Z
SUMMARY:Robust timed synthesis
DESCRIPTION:Speaker: Youssouf Oualhadj (Université Paris-Est Créteil Val 
 de Marne)\n\nAbstract: \nSolving games played on timed automata is a well-
 known problem and has led to tools and industrial case studies. In these g
 ames\, the first player (Controller) chooses delays and actions and the se
 cond player (Perturbator) resolves the non-determinism of actions. However
 \, the model of timed automata suffers from mathematical idealizations suc
 h as infinite precision of clocks and instantaneous synchronization of act
 ions. To address this issue\, we extend the theory of timed games in two d
 irections. First\, we study the synthesis of robust strategies for Control
 ler which should be tolerant to adversarially chosen clock imprecisions. S
 econd\, we address the case of a stochastic perturbation model where both 
 clock imprecisions and the non-determinism are resolved randomly. Finally 
 we present a notion "repair" where we explain how to recover robustness in
  non-robust systems.\nShort Bio:\nDr. Oualhadj is interested in algorithmi
 c game theory and its application to verification and synthesis. He is a 
 senior lecturer in the Computer Science Department of Université Paris-Es
 t Créteil Val de Marne and also a member of the Specification and Verific
 ation of Systems team in the Logic\, Algorithms\, and Complexity Laborator
 y (LACL).\nFrom November 2013 to August 2014\, he held a postdoctoral posi
 tion in the Computer Science Institute of Mons University (UMons) in the T
 heoretical Computer Science team led by Véronique Bruyère. From October
  2012 to September 2013\, he held a postdoctoral position in the MoVe team
  (LIF) within the project ECSPER at Aix Marseille University. For his PhD
  thesis\, he worked under the supervision of Anca Muscholl and Hugo Gimber
 t on stochastic games.\n
URL:https://www.tcs.tifr.res.in/web/events/1530
DTSTART;TZID=Asia/Kolkata:20250429T160000
DTEND;TZID=Asia/Kolkata:20250429T170000
LOCATION:HBA Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1537
DTSTAMP:20250424T101721Z
SUMMARY:Complexity of imperfect recall games
DESCRIPTION:Speaker: B. Srivathsan (Chennai Mathematical Institute)\n\nAbst
 ract: \nWe look at two player zero-sum games played on trees. When players
  have perfect information about their state of the game\, finding max-min 
 strategies is easily done by a bottom-up scan of the game-tree. If players
  do not have perfect information about the state of the game\, but still\,
  they remember their own history of actions\, they are said to have perfec
 t recall. Max-min strategies in perfect recall games can be synthesized in
  polynomial-time. When players forget even their own history of actions\, 
 they are said to have imperfect recall. Solving imperfect recall games is 
 known to be NP-hard.In this talk\, we will present new complexity results 
 for imperfect recall games: firstly\, we show that they are as hard as sol
 ving certain problems in the first order theory or reals\, and secondly\, 
 we propose new polynomial-time solvable fragments of imperfect recall game
 s.Joint work with Hugo Gimbert\, Kristoffer Arnsfelt Hansen and Soumyajit 
 Paul.\nShort Bio:\nB Srivathsan is a faculty member at the Chennai Mathema
 tical Institute. He earned his PhD from the University of Bordeaux\, and h
 is Masters and Bachelors from IIT Bombay. His research interests lie in th
 e areas of automata theory\, games and formal verification. \n
URL:https://www.tcs.tifr.res.in/web/events/1537
DTSTART;TZID=Asia/Kolkata:20250506T160000
DTEND;TZID=Asia/Kolkata:20250506T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1532
DTSTAMP:20250507T050439Z
SUMMARY:Fair distribution of MEV in blockchains through Shapley Value
DESCRIPTION:Speaker: Sujit Gujar (International Institute of Information Te
 chnology\, Hyderabad (IIITH))\n\nAbstract: \nIn blockchains\, by simply re
 arranging transactions or leveraging opportunities across multiple exchang
 es\, a miner can extract more value than just collecting block rewards and
  transaction fees. This additional value is known as Maximal Extractable 
 Value (MEV) (formerly referred to as Miner Extractable Value). However\,
  extracting MEV requires additional resources and has given rise—especia
 lly in blockchain markets like Ethereum—to entities called builders. A 
 builder collects publicly known transactions as well as transactions purch
 ased from wallet service providers and constructs blocks designed to maxim
 ize MEV extraction. Such extraction amounts to millions of dollars annuall
 y.\nThis gives rise to two key questions:\nDo builders receive fair compe
 nsation for their work?\nDo transaction creators receive any reward for th
 eir transactions generating MEV?\nIn this talk\, we show that a cooperati
 ve game theory approach is better suited to model this situation. For the
  first question\, we demonstrate that the Shapley value can enhance fair
 ness in the system\, and that a cooperative approach can lead to higher ME
 V extraction than the traditional competitive methods. While computing the
  Shapley value is generally computationally challenging\, we derive a clo
 sed-form solution that can be computed in polynomial time.\nFor the seco
 nd question\, we model a separate cooperative game based on the revenue ge
 nerated\, involving wallet service providers\, and transaction creators. I
 f builders' valuations are additive\, one can easily deduce that the Shap
 ley values of the transactions. However\, we conjecture that if valuatio
 ns are single-minded\, then computing the Shapley value becomes a SUBEXP
  problem. To address this\, we present a simple sampling algorithm wit
 h PAC (Probably Approximately Correct) guarantees for approximating Shapl
 ey values.\n \nShort Bio:\nCurrently\, Dr. Sujit Gujar is working as an A
 ssociate Professor at the International Institute of Information Technolog
 y\, Hyderabad (IIITH).  He holds the CA Technologies Faculty Chair positi
 on at IIITH. His expertise is in Game Theory\, Blockchains and distributed
  AI. He has co-authored 100+ international peer-reviewed publications and 
 has filed 15+ patents in US. Prior to IIITH\, he was a post-doctoral resea
 rcher with Prof Boi Faltings\, LIA\, EPFL\, Lausanne (Jan'14-Oct'15)\, and
  a Sr Research Associate with Prof Y Narahari (Nov'15-Apr'16).  He also h
 as an expereience as a Research Scientist at Xerox Research Centre India (
 Jan'11-Nov'13).   He completed his Ph.D. in the Department of Computer Sc
 ience and Automation @ the Indian Institute of Science\, Bangalore. He wor
 ked with Prof Y Narahari\, in the Game Theory Lab. He is a recipient of th
 e Alumni Medal of IISc for the Best Thesis in CSA for the academic year 20
 11-12' for his Ph.D. Dissertation.\n
URL:https://www.tcs.tifr.res.in/web/events/1532
DTSTART;TZID=Asia/Kolkata:20250513T160000
DTEND;TZID=Asia/Kolkata:20250513T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1553
DTSTAMP:20250515T092022Z
SUMMARY:Algebraic Independence Testing
DESCRIPTION:Speaker: Shanthanu  Suresh Rai (TIFR)\n\nAbstract: \nQuestion: 
 Are the given set of multivariate polynomials f_1\, ...\, f_k algebraicall
 y dependent? In other words\, is there a non-zero polynomial g such that g
 (f_1\, ...\, f_k) = 0?\nWe will see that algebraic independence shares the
  matroid structure of linear independence. We show this connection with th
 e help of partial derivatives of f_i (in particular\, using the Jacobian m
 atrix). From the Jacobian criteria\, we can show that algebraic independen
 ce testing is in RP.\nBut the above Jacobian criteria is valid over fields
  of characteristic 0\, like the complex numbers. In particular\, it is not
  valid over finite fields. Thus the problem of algebraic independence test
 ing over finite fields is wide open.\nWe will see that over finite fields\
 , algebraic independence testing is in AM ∩ coAM.\nLink to paper: https
 ://arxiv.org/abs/1801.09275\n
URL:https://www.tcs.tifr.res.in/web/events/1553
DTSTART;TZID=Asia/Kolkata:20250516T160000
DTEND;TZID=Asia/Kolkata:20250516T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1535
DTSTAMP:20250516T082610Z
SUMMARY:Fair Rank Aggregation
DESCRIPTION:Speaker: Diptarka Chakraborty (National University of Singapore
 )\n\nAbstract: \nAggregating multiple input rankings over a set of candida
 tes to generate a consensus ranking is one of the fundamental ranking prob
 lems\, having many applications in social choice theory\, hiring\, college
  admission\, web search\, and databases. However\, the optimal consensus r
 anking might be biased against any individual candidate or candidates belo
 nging to certain marginalized communities or groups. This has motivated st
 udies of the rank aggregation problem from the fairness perspective. While
  finding a consensus ranking\, the additional objective is to ensure fair 
 representation of each group in the top positions of the final aggregated 
 ranking. In this talk\, we will discuss various algorithms to find such a 
 fair ranking approximately.\nShort Bio:\nDiptarka is an assistant professo
 r at the National University of Singapore. He did his Ph.D. at the Indian 
 Institute of Technology\, Kanpur. Before joining NUS\, he spent two years 
 at Charles University\, Prague\, and then almost a year at Weizmann Instit
 ute of Science\, Israel\, as a post-doctoral fellow. His research interest
  mostly lies in theoretical computer science\, more specifically\, algorit
 hms on large data sets\, approximation algorithms\, sublinear algorithms\,
  string matching algorithms\, and graph algorithms. He is a recipient of t
 he best paper award at FOCS 2018 and the Google South & Southeast Asia Res
 earch Award 2022.\n
URL:https://www.tcs.tifr.res.in/web/events/1535
DTSTART;TZID=Asia/Kolkata:20250520T160000
DTEND;TZID=Asia/Kolkata:20250520T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1555
DTSTAMP:20250522T095346Z
SUMMARY:Cutting Planes and Monotone Feasible Interpolation
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nCu
 tting Planes is a proof system which certifies a system of linear inequali
 ties has no integer solution by repeatedly deriving new inequalities by li
 near combinations and rounding-up of previous inequalities. As a proof sys
 tem\, it is strictly stronger than resolution - and lower bounds for it ar
 e hard to prove. The only known technique is the Monotone Interpolation Pr
 operty\, which in turn uses lower bounds from monotone circuit complexity.
  However\, currently this technique can be used only for a very restrictiv
 e set of CNFs - it's not yet known if random constant-width CNFs are hard 
 for Cutting Planes. We shall describe the MIP technique and mention some o
 pen problems on which there has been exciting progress in the past few yea
 rs.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1555
DTSTART;TZID=Asia/Kolkata:20250523T160000
DTEND;TZID=Asia/Kolkata:20250523T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1534
DTSTAMP:20250520T051651Z
SUMMARY:FPT Approximation Algorithms for Multiwinner Rules: Max Coverage & 
 Beyond
DESCRIPTION:Speaker: Pallavi Jain (IIT Jodhpur)\n\nAbstract: \nMax Coverage
  is a classical NP-hard problem that remains hard to approximate\, even in
  fixed-parameter tractable (FPT) time. In this talk\, we will discuss the 
 FPT approximation algorithms for Max Coverage and related problems\, under
  certain structural restrictions on the set family. Notably\, Max Coverage
  is equivalent to the well-known Chamberlin–Courant rule in multiwinner 
 voting\, which seeks to select a representative committee based on voters'
  preferences. In this talk\, we will discuss the recent advances in FPT ap
 proximation algorithms for a broad class of voting rules that generalize t
 he Chamberlin–Courant rule.The talk is based on the following two papers
 . (1) Parameterized Approximation Algorithms for MAX-SAT with Cardinality
  Constraint and Maximum Coverage\, L. Kanesh\, P. Jain\, F. Panolan\, S. S
 aha\, A. Sahu\, S. Saurabh\, and A. Upasana\, SODA 2023.(2) More Efforts T
 owards Fixed-Parameter Approximability of Multiwinner Rules\, S. Gupta\, P
 . Jain\, S. Saha\, S. Saurabh\, and A. Upasana\, accepted in IJCAI 2025. 
  Short Bio:Pallavi Jain is an Assistant Professor at the Indian Institut
 e of Technology Jodhpur. She is a theoretical computer scientist with res
 earch interests in Computational Social Choice Theory\, a field at the in
 tersection of Economics and Computer Science\, Graph Algorithms\, and
  Parameterized Complexity. Most of her current work centers on modeling r
 eal-world problems that involve collective decision-making\, with a partic
 ular focus on fairness and efficiency. She explores both the classical and
  parameterized complexity of these problems.Before joining IIT Jodhpur\, P
 allavi was a postdoctoral fellow at Ben-Gurion University of the Negev\, 
 Israel. She also held a SERB-NPDF position at the Institute of Mathemat
 ical Sciences\, Chennai. She obtained her Ph.D. from Dayalbagh Education
 al Institute\, Agra.\n
URL:https://www.tcs.tifr.res.in/web/events/1534
DTSTART;TZID=Asia/Kolkata:20250527T160000
DTEND;TZID=Asia/Kolkata:20250527T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1556
DTSTAMP:20250528T105344Z
SUMMARY:Communication complexity\, but everything is vectors
DESCRIPTION:Speaker: Suhail Sherif (University of Lisbon)\n\nAbstract: \nTh
 is talk is about replacing bits with vectors. Goemans and Williamson did t
 his for MAX-CUT and got the best known polynomial-time approximation algor
 ithm. We wanted to know whether moving to vectors will help us prove certa
 in communication complexity lower bounds (and hopefully circuit depth lowe
 r bounds too). Moving to vectors has a strong benefit (via duality\, "shor
 t" lower bound proofs are guaranteed for all lower bounds) but one downsid
 e (some hard functions may become easy). To analyze this question we creat
 e two natural vector variants of communication protocols (both phrased as 
 Semidefinite Programs)\, and we set out to prove lower bounds for the Equa
 lity function. Our results are as follows:\n- The natural vector variant o
 f the Pigeonhole Principle is true.- Nevertheless in both of these communi
 cation variants Equality is actually easy to compute! (This implies that t
 he circuit depth lower bounds are also not achievable.)\nAfter this work w
 e realized that a work of Austrin and Risse already show a no-go theorem: 
 circuit depth lower bounds can not be achieved through semidefinite progra
 ms! Given this we will focus on the parts of our paper that are not covere
 d by theirs: The Pigeonhole Principle variant\, and results about the comm
 unication variants that are not directly linked to the circuit no-go theor
 em.\nThis is joint work with Pavel Dvorák and Bruno Loff.\n
URL:https://www.tcs.tifr.res.in/web/events/1556
DTSTART;TZID=Asia/Kolkata:20250529T160000
DTEND;TZID=Asia/Kolkata:20250529T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1557
DTSTAMP:20250529T090355Z
SUMMARY:Introduction to pseudo-random correlation generators
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \nIn offline-onl
 ine multi-party computation protocols\, the offline phase often involves s
 etting up of input-independent random variables and the online phase invol
 ves a fast computation of the function once the inputs arrive. Unfortunate
 ly\, the offline phase can be slow and can involve a lot of communication 
 between parties. Pseudo-random correlation generators (PCGs) partially sol
 ve this problem by letting the parties communicate small correlated seeds 
 and then letting them expand them locally to generate long correlated stri
 ngs for the online phase. In this talk\, we will see the construction of a
  PCG by Boyle\, Couteau\, Gilboa\, Ishai\, Kohl and Scholl\, CRYPTO-2019.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1557
DTSTART;TZID=Asia/Kolkata:20250530T160000
DTEND;TZID=Asia/Kolkata:20250530T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1552
DTSTAMP:20250528T062527Z
SUMMARY:Efficient LLM Inference with HiRE and Tandem Transformers
DESCRIPTION:Speaker: Praneeth Netrapalli (Google)\n\nAbstract: \nLarge Lang
 uage Models (LLMs) often suffer from memory-bound inference on accelerator
 s\, impacting latency of all the key layers: feedforward\, attention\, and
  softmax. Despite significant sparsity within these layers\, efficient exp
 loitation is hindered by a lack of accelerator support for unstructured sp
 arsity and the computational cost of identifying important elements. We in
 troduce HiRE\, a novel technique that utilizes dimensionality reduction an
 d quantization to predict the significant elements with high recall\, foll
 owed by focused computation and an efficient approximate top-k operator. 
  Applied to softmax and a group-sparse FFN layer\, HiRE significantly redu
 ces computational cost while preserving accuracy\, leading to improved end
 -to-end inference latency.Furthermore\, we tackle the inherent sequential 
 generation bottleneck of LLMs with tandem transformers. This architecture 
 combines a small autoregressive model with a large block-mode model\, wher
 e the small model leverages the large model's representations for improved
  accuracy. This results in enhanced prediction\, faster inference\, and th
 e option of a verification step to ensure quality. Our approach demonstrat
 es superior performance compared to standalone models and addresses the li
 mitations of existing parallel decoding techniques.Based on joint works wi
 th Yashas Samaga B L\, Varun Yerram\, Aishwarya P S\, Pranav Nair\, Srinad
 h Bhojanapalli\, Chong You\, Toby Boyd\, Sanjiv Kumar and Prateek Jain.\nS
 hort Bio:\nPraneeth Netrapalli is a research scientist at Google Research 
 India\, Bengaluru. He is also an adjunct professor at CMInDS\, IIT Bombay 
 and TIFR\, Mumbai and a faculty associate of ICTS\, Bengaluru. Prior to th
 is\, he was a researcher at Microsoft Research. He obtained MS and PhD in 
 ECE from UT Austin\, and B-Tech in EE from IIT Bombay. He is a co-recipien
 t of IEEE Signal Processing Society Best Paper Award 2019\, Indian Nationa
 l Science Academy (INSA) Medal for Young Scientists 2021 and was an associ
 ate of Indian Academy of Sciences (IASc) 2019-2022. His current research i
 nterests are broadly around improving efficiency and capabilities of LLMs.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1552
DTSTART;TZID=Asia/Kolkata:20250603T160000
DTEND;TZID=Asia/Kolkata:20250603T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1559
DTSTAMP:20250606T045327Z
SUMMARY:Are Three Petersens Enough?
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nThe Petersen gr
 aph is perhaps the most well-known 3-regular graph on 10 vertices. Donald 
 Knuth states (in one of his many many books) that the Petersen graph is "a
  remarkable configuration that serves as a counterexample to many optimist
 ic predictions about what might be true for graphs in general." In this ta
 lk\, we will ignore all of that and instead consider the following problem
 : can three isomorphic copies of the Petersen graph cover the complete gra
 ph on 10 vertices? While a brute-force approach should reveal the answer\,
  we will take a spectral approach to solve this problem. The talk will be 
 based on a chapter from Jiří Matoušek's book "Thirty-three miniatures."
 \n
URL:https://www.tcs.tifr.res.in/web/events/1559
DTSTART;TZID=Asia/Kolkata:20250606T160000
DTEND;TZID=Asia/Kolkata:20250606T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1554
DTSTAMP:20250603T045458Z
SUMMARY:Robustness in AI Systems: From Statistical Foundations to Language 
 Model Consistency
DESCRIPTION:Speaker: Subho Majumdar (Vijil)\n\nAbstract: \nThe principles o
 f robust estimation\, designed to maintain performance under distributiona
 l deviations and data corruption\, are a cornerstone of reliable statistic
 al inference. Despite their impressive capabilities\, large language model
 s (LLMs) often produce inconsistent outputs when presented with semantical
 ly equivalent inputs\, undermining their reliability in critical applicati
 ons. This inconsistency mirrors classical robustness problems in statistic
 s\, where small perturbations in input can lead to dramatically different 
 outcomes.\n \nI will present two interconnected lines of work in this are
 a. First\, I will talk about robust high-dimensional regression using dens
 ity power divergence\, a generalization of the maximum likelihood techniqu
 e\, and a number of fundamental results on the asymptotics and influence f
 unction of the resulting robust estimators. Second\, I discuss my work on 
 the consistency problem---the equivalent of robustness in LLMs---concerned
  with measuring and minimizing the sensitivity of LLM outputs to input var
 iations through a combination of controlled synthetic data generation and 
 fine-tuning.\n \nThe talk will conclude with a discussion of open problem
 s at the intersection of classical robustness methods and AI consistency\,
  including robust training techniques and influence function analysis\, fo
 r ensuring AI system reliability in high-stakes applications.\nShort Bio:\
 nSubho Majumdar is co-founder and head of AI at Vijil\, a US-based startup
  that helps enterprises build and operate trustworthy AI agents. Previousl
 y\, he was a senior scientist in the security research team at Splunk and 
 the Data Science and AI Research team at AT&T Labs. He has pioneered the u
 se of trustworthy AI methods in multiple companies\, wrote a book\, and fo
 unded multiple nonprofit efforts in this area. He is a recipient of the In
 ternational Indian Statistical Association (IISA) Early Career Award in St
 atistics and Data Sciences. His research interests are on the security and
  reliability of LLMs and statistical machine learning.\n
URL:https://www.tcs.tifr.res.in/web/events/1554
DTSTART;TZID=Asia/Kolkata:20250610T093000
DTEND;TZID=Asia/Kolkata:20250610T103000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1566
DTSTAMP:20250611T112615Z
SUMMARY:Sequential Decision-Making under Uncertainty and Constraints: A Syn
 thesis of Differential Games and Stochastic Bandits
DESCRIPTION:Speaker: Sushant Vijayan (TIFR)\n\nAbstract: \nIn this thesis\,
  we study sequential decision making problems under uncertainty and constr
 aints. We consider four different problems:\nFor online regret minimizatio
 n in linear bandits with ${prior}$ observations\, we propose a phased elim
 ination algorithm ${OOPE}$ and give its regret upper bound in terms of the
  offline data's Grammian eigenspectrum. We establish regret lower bounds t
 hat help establish the minimax optimality of OOPE in certain regimes and i
 mprove on existing work. This also shows that the quality of offline data 
 is well measured by the eigenspectrum of the Grammian matrix of the offlin
 e data.\nIn automated bidding systems with ${unknown value}$ and long-term
  budget and Return-on-Spend (RoS) constraints\, a UCB-based computationall
 y efficient algorithm is developed. We do away with restrictive assumption
 s like strict Slater feasibility\, truthfulness of the auction\,  and obt
 ain optimal regret and constraint violation bounds with logarithmic depend
 ence on the bid domain size.\nWe model infectious disease spread as a diff
 erential game between a planner and the populace\, characterizing ${open-l
 oop}$ Nash equilibria using Pontryagin's Minimum Principle. We use the dev
 eloped model to study the qualitative characteristics in equilibrium and b
 ring out the crucial roles of infection detection rates and public trust i
 n reported infection numbers. \nFor Active Simple Hypothesis Testing (ASH
 T) with a fixed budget\, we characterize the minimax error exponent as the
  value of a zero-sum differential game. This reformulation leads to a more
  computationally tractable algorithm compared to prior work. This problem 
 has attracted significant interest in many different research communities 
 like Simulation\, Operation Research\, Information Theory and Bandits. Thi
 s characterization of the error exponent and the development of provably o
 ptimal\, computationally tractable algorithm constitute significant progre
 ss into the problem. However\, even this provably optimal algorithm suffer
 s from a \\emph{curse of dimensionality}. We propose a more efficient algo
 rithm leveraging a novel link to Blackwell Approachability. This more effi
 cient approachability algorithm provably outperforms non-adaptive strategi
 es and is numerically verified to attain the optimal exponent in certain i
 nstances.\nThe first two problems utilize only bandit techniques and the t
 hird employs methods of differential games\; the final problem combines di
 fferential game theory with a classical bandit setup\, showcasing a ${synt
 hesis}$ of both distinct and integrated applications of these two framewor
 ks.\n
URL:https://www.tcs.tifr.res.in/web/events/1566
DTSTART;TZID=Asia/Kolkata:20250613T153000
DTEND;TZID=Asia/Kolkata:20250613T163000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1567
DTSTAMP:20250612T104559Z
SUMMARY:Computing the Cost of Replacing Connections in a Distributed Way.
DESCRIPTION:Speaker: Dipan Dey (TIFR)\n\nAbstract: \nThe shortest path prob
 lem is one of the central problems in graph theory and algorithms. In the 
 Replacement Path problem\, we are given the source vertex s\, the target v
 ertex t\, and theshortest path between them. The goal is to compute the co
 st of replacing each edge in this path - that is\, for every edge ee on th
 e shortest path\, we must find the length of the shortest path from ss to 
 tt that avoids ee.We study this problem from a distributed perspective\, w
 here computational power and responsibility are distributed among the vert
 ices. The algorithm presented will be in the CONGEST model.This talk is ba
 sed on my recently accepted work\, Optimal Distributed Replacement Paths\,
  accepted in PODC 2025\, coauthored with Yi-Jun Chang\, Yanyu Chen\, Gopin
 ath Misra\, Hung Thuan Nguyen\, and Bryce Sanchez.The arXiv version of the
  paper can be found here: https://arxiv.org/pdf/2502.15378\n
URL:https://www.tcs.tifr.res.in/web/events/1567
DTSTART;TZID=Asia/Kolkata:20250613T171500
DTEND;TZID=Asia/Kolkata:20250613T181500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1525
DTSTAMP:20250131T112724Z
SUMMARY:Vigyan Vidushi 2025
DESCRIPTION:Speaker: \n\nAbstract: \nThe STCS Vigyan Vidushi 2025 program
 me is a summer school to introduce women with undergraduate and postgradua
 te background to advanced topics in theoretical computer and systems scien
 ces. The two-week programme will be held during the period 16th June – 
 27th June 2025 at the TIFR Mumbai campus\, and will consist of short te
 chnical courses taught by faculty members from STCS\, TIFR and other res
 earch institutes. Lectures will be supplemented by problem-solving session
 s\, to enhance students’ understanding.\nhttps://www.tcs.tifr.res.in/~st
 cs-vv-25/\n
URL:https://www.tcs.tifr.res.in/web/events/1525
DTSTART;VALUE=DATE:20250616
DTEND;VALUE=DATE:20250628
LOCATION:TIFR\, Mumbai.
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1561
DTSTAMP:20250610T045248Z
SUMMARY:Quantum Computing: Quo Vadis?
DESCRIPTION:Speaker: Prabha Mandayam (IIT Madras)\n\nAbstract: \nQuantum sc
 ience and technologies have taken giant strides over the last decade. For 
 the first time since the advent of quantum theory\, it is now possible to 
 build and precisely control complex quantum states of many particles. We a
 re today in an era of noisy\, intermediate-scale quantum (NISQ) devices\, 
 with companies such as IBM and Google showcasing quantum devices with hund
 reds of quantum bits (qubits). This begs the question\, how close are we t
 o truly realizing a quantum computer? In what ways are quantum computers m
 ore powerful than their classical counterparts\, and where do they derive 
 this “power” from? In this talk we will try to address these questions
 \, providing a glimpse into several interesting facets of the quantum worl
 d along the way. We will conclude with a brief discussion of the challenge
 s that lie ahead\, on the route to scaling up from NISQ devices to univers
 al\, fault-tolerant quantum computers.\nShort Bio:Prabha is an associate p
 rofessor in the department of Physics at the Indian Institute of Technolog
 y\, Madras. Prior to this\, she was an Inspire faculty fellow at the Chenn
 ai Mathematical Institute and a Post-doctoral Fellow with the Optics and Q
 uantum Information Group at the Institute of Mathematical Sciences. She ob
 tained her PhD in Physics from the Institute for Quantum Information and M
 atter at Caltech. Her research interests are broadly in the area of quantu
 m computing and quantum information theory\, and in particular in quantum 
 error correction\, and understanding the interplay between quantum foundat
 ions and quantum cryptography\, and using quantum information as a tool to
  explore fundamental questions in theoretical physics.\n
URL:https://www.tcs.tifr.res.in/web/events/1561
DTSTART;TZID=Asia/Kolkata:20250617T160000
DTEND;TZID=Asia/Kolkata:20250617T173000
LOCATION:AG-69
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1568
DTSTAMP:20250617T061704Z
SUMMARY:Prophet Inequality and Secretary Problem
DESCRIPTION:Speaker: Pranab Panda (TIFR)\n\nAbstract: \nIn the talk we will
  look at the classical prophet inequality and its closely related secretar
 y problem. These problems deal with sequential decision-making under uncer
 tainty\, such as selecting the best item from a sequence or maximizing rev
 enue in posted price mechanisms. I will present recent advancements\, incl
 uding the order selection prophet inequality\, IID prophet inequality\, an
 d results on achieving logarithmic regret in the multi-secretary problem.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1568
DTSTART;TZID=Asia/Kolkata:20250620T143000
DTEND;TZID=Asia/Kolkata:20250620T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1562
DTSTAMP:20250609T093423Z
SUMMARY:Creating datasets for environmental sustainability problem in devel
 oping countries
DESCRIPTION:Speaker: Rijurekha Sen (IIT Delhi)\n\nAbstract: \n\nData analyt
 ics\, big data\, machine learning\, artificial intelligence etc. are words
  dominating our research and industry discourses these days. We believe th
 at if we had enough data\, to understand our biggest problems like air pol
 lution or climate change\, we would be able to better tackle these menaces
 . AI for Social Good (Google) or AI for Earth (Microsoft) are example gran
 t programs trying to develop AI algorithms to process environmental sustai
 nability datasets. However\, creating the necessary environmental datasets
  in developing countries is hard. Delhi-NCR\, for example\, covers 55K squ
 are KMs\, but has only 35 air quality monitoring stations\, even with the 
 whole world’s attention focussed on this city’s pollution problems. Me
 asurement infrastructure in other parts of the country is worse. Budget co
 nstraints\, lack of domestic instrument production increasing procurement 
 and maintenance costs from foreign countries\, lack of broadband network s
 o that deployed sensors can easily send data from the field to remote serv
 ers for processing — all play a role in this data paucity problem. In th
 is talk\, I’ll highlight how embedded systems/edge computing/IoT (same t
 hing\, different names) can augment this data generation process for susta
 inability problems in developing countries. I’ll use two examples of air
  pollution monitoring using Delhi public buses and traffic monitoring on D
 elhi Ring Road intersections. The talk will touch upon the low level sensi
 ng and embedded processing pipeline including embedded deep neural network
 s\, software verification and remote attestation methods to ensure device 
 security\, privacy issues with the collected data data when different indu
 stry partners are involved\, and AI/ML on the aggregated datasets for urba
 n policy analysis like odd-even traffic rule.\nShort Bio:Rijurekha is an a
 ssistant professor in the department of computer science and engineering a
 t the Indian Institute of Technology Delhi. Her research interests are in 
 problems at the intersection of information technology and society\, and i
 n particular on building distributed\, networked and privacy aware systems
 . This includes work on building systems for road traffic monitoring\, hum
 an mobility measurements\, public policy audit and privacy enhancement in 
 ubiquitous systems\, among others. Before moving to IIT Delhi\, Rijurekha 
 did her PhD at IIT Bombay and was a postdoc at the Max Planck Institute fo
 r Software Systems at Saarbrucken in Germany.\n
URL:https://www.tcs.tifr.res.in/web/events/1562
DTSTART;TZID=Asia/Kolkata:20250620T160000
DTEND;TZID=Asia/Kolkata:20250620T173000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1563
DTSTAMP:20250609T093541Z
SUMMARY:Games as Mathematics: SET and cap-sets
DESCRIPTION:Speaker: Jyothi Krishnan (IIT Gandhinagar)\n\nAbstract: \nIn th
 is talk we will play the game of SET and then\, using insights from the ga
 me\, formulate the maximal cap-set problem and prove it for some special c
 ases.\nShort Bio:Jyothi Krishnan grew up solving puzzles and reading Marti
 n Gardner’s books. Not realising that recreational mathematics provided 
 any scope for a career\, she pursued her other love of mechanics and colle
 cted a BTech from NIT Calicut\, an MS from IIT Madras and a PhD from UC Be
 rkeley. She has worked as a programmer\, a bridge engineer\, a research ma
 thematician and a school teacher. Having been introduced to the world of m
 odern board games during her PhD\, she realised that it was a way to make 
 fairly complicated mathematical reasoning accessible to a large number of 
 children so she created a job playing games with kids in an alternative sc
 hool in Bangalore. After running her game lab for 4 years she discovered l
 ike-minded people at CCL where she is thrilled to be making a living playi
 ng games and solving puzzles. At CCL she creates games and looks after mat
 h content.\n
URL:https://www.tcs.tifr.res.in/web/events/1563
DTSTART;TZID=Asia/Kolkata:20250623T160000
DTEND;TZID=Asia/Kolkata:20250623T173000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1564
DTSTAMP:20250609T093847Z
SUMMARY:Making Science Speak: A Window into Careers in Science Communicatio
 n
DESCRIPTION:Speaker: Uzma Shaikh (TIFR)\n\nAbstract: \nIn this interactive 
 session\, we will explore what it means to build a career in science commu
 nication—why it matters\, the many forms it can take\, and how researche
 rs and professionals are shaping public engagement with science in India a
 nd beyond. From writing and video production to exhibitions\, policy\, and
  grassroots outreach\, we’ll dive into real-world case studies of Indian
  science communicators\, including several who transitioned from STEM care
 ers to storytelling\, education\, and advocacy. The session will include a
  short activity designed to get participants thinking about the kinds of s
 tories they want to tell and the audiences they want to reach.\nShort Bio:
 Uzma Shaikh is a science communicator at the Tata Institute of Fundamental
  Research (TIFR)\, Mumbai\, where she works at the intersection of researc
 h\, public engagement\, and visual storytelling. She holds a Master’s de
 gree in Microbiology from St. Xavier’s College\, Mumbai\, and has previo
 usly worked at the Homi Bhabha Centre for Science Education (HBCSE)\, cont
 ributing to the development of experimental science modules for student an
 d teacher enrichment programs. Uzma is a freelance scientific illustrator\
 , with her illustrations most recently featured in the book Vanishing Life
  on Earth by Prof. Bimalendu Nath. Uzma is also a writer and designer for 
 Anandi\, HBCSE’s Marathi-language science newsletter that reaches over 4
 \,000 students in rural Maharashtra. In addition to her institutional role
 s\, she leads The Bio Brigade\, an independent science outreach initiative
  through which she engages school students in exploring biology beyond the
  classroom. Her broader practice reflects a deep commitment to making scie
 nce accessible\, engaging\, and contextually relevant through creative for
 mats. When not communicating science\, she enjoys building paper models an
 d designing science-themed apparel.\n
URL:https://www.tcs.tifr.res.in/web/events/1564
DTSTART;TZID=Asia/Kolkata:20250625T160000
DTEND;TZID=Asia/Kolkata:20250625T173000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1576
DTSTAMP:20250626T072117Z
SUMMARY:Coding for Interactive Communication
DESCRIPTION:Speaker: Bikshan Chatterjee (TIFR)\n\nAbstract: \nWhen we want 
 to transfer a single message from one computer to another over a noisy wir
 e\, we use Error Correcting Codes. Now suppose we have two computers inter
 acting with each other over a noisy wire\, say they are playing a game whe
 re each move is a small message and depends on all the prior moves. It tur
 ns out that error correcting codes are suboptimal for protecting these int
 eractive protocols against noise\, the idea being that the interaction its
 elf can be used for error correction. The field of "Coding for Interactive
  Communication" was developed to study these error resilient interactive p
 rotocols. We will look at the first result in the area from 1992\, and a b
 rief summary of later research directions.\nReference: https://ieeexplore.
 ieee.org/document/267778\n \n
URL:https://www.tcs.tifr.res.in/web/events/1576
DTSTART;TZID=Asia/Kolkata:20250627T160000
DTEND;TZID=Asia/Kolkata:20250627T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1565
DTSTAMP:20250701T050625Z
SUMMARY:Coresets for tensor factorization and deterministic Lp embedding
DESCRIPTION:Speaker: Anirban Dasgupta (IIT Gandhinagar)\n\nAbstract: \nIn t
 he face of the data onslaught\, smart algorithms have a significant role t
 o play. Over the last couple of decades\, coresets\, a small and efficient
 ly calculable data summary\, have grown in popularity\, both in theoretica
 l and practical settings. They enable approximating large optimizations wh
 ile needing only a fraction of the resources. In this talk\, we will discu
 ss a few recent results related to creating coresets for two related probl
 ems ----(symmetric) tensor factorization and Lp subspace embedding. Our co
 resets for tensor factorization are online in nature\, i.e.\, for every in
 coming point\, it takes an irrevocable decision whether to include it in t
 he coreset. \n \nFor Lp subspace embedding we also present a determinist
 ic coreset by generalizing the work of Batson\, Spielman\, Srivastava (BSS
 ) and extending it from L2 to Lp. \n \nShort Bio: Anirban Dasgupta is cu
 rrently the N. Rama Rao Chair Professor of Computer Science & Engineering 
 at IIT Gandhinagar. Prior to being at IIT Gandhinagar\, he was a Senior Sc
 ientist at Yahoo Labs Sunnyvale. Anirban works on algorithmic problems for
  massive data sets\, large-scale machine learning\, analysis of large soci
 al networks\, and randomized algorithms in general. He did his undergradua
 te studies at IIT Kharagpur and doctoral studies at Cornell University. He
  has received the Google Faculty Research Award (2015)\, the Cisco Univers
 ity Award (2016)\, the ICDT Best Newcomer Award (2016)\, the Google India 
 AI/ML Award (2020)\, and the ACM STOC 10 year Test of Time award in 2024.\
 n \n
URL:https://www.tcs.tifr.res.in/web/events/1565
DTSTART;TZID=Asia/Kolkata:20250701T160000
DTEND;TZID=Asia/Kolkata:20250701T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1569
DTSTAMP:20250630T054630Z
SUMMARY:Building advanced cryptography for distributed settings.
DESCRIPTION:Speaker: Anshu Yadav (Institute of Science and Technology Austr
 ia)\n\nAbstract: \nIn today's world\, rapid technological advancement has 
 led to the generation of vast amounts of sensitive data\, often in a distr
 ibuted manner. Ensuring secure and controlled access to this data\, while 
 avoiding single points of failure\, presents natural yet complex challenge
 s in modern cryptography. My research explores how advanced cryptographic 
 primitives can address these challenges.\nIn this talk\, I will begin with
  a brief overview of my research interests\, and then focus on one key the
 me: multi-input attribute-based encryption (k-ABE). This is a generalizati
 on of attribute-based encryption (ABE)\, which allows expressive access co
 ntrol over encrypted data. In ABE\, a message is encrypted under an attrib
 ute x\, and decryption keys correspond to policies f\, allowing decrypti
 on only if f(x) = 1. In the multi-input setting\, data is generated indep
 endently by k parties\, each with input (x_i\, m_i). A decryption key f
 or a k-ary predicate f can recover all messages if and only if f(x₁\
 ,...\,x_k) = 1. I will outline our formalization of k-ABE and highlight co
 nstructions under various assumptions. If time permits\, I will briefly me
 ntion my work on threshold signatures and conclude with future research di
 rections and open problems.\nShort Bio: Anshu Yadav is currently a postdo
 ctoral researcher at IST Austria. She received her PhD from IIT Madras\, g
 uided by Prof. Shweta Agrawal. Her research interests are in the area of t
 heoretical cryptography in building various cryptographic primitives large
 ly from post-quantum lattice-based cryptographic assumptions and some from
  classical assumptions as well. \n
URL:https://www.tcs.tifr.res.in/web/events/1569
DTSTART;TZID=Asia/Kolkata:20250703T160000
DTEND;TZID=Asia/Kolkata:20250703T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1575
DTSTAMP:20250625T045401Z
SUMMARY:Adversarial Hypothesis Testing: Channel Estimation\, Sequentiality 
 and Robustness
DESCRIPTION:Speaker: Eeshan Modak (TIFR)\n\nAbstract: \nIn this thesis\, we
  study the following problems:\nAdversarial hypothesis testing is a model 
 for problems where the observed data is not independent and identically di
 stributed according to a fixed distribution. The samples could instead com
 e from distributions arbitrarily chosen by an adversary. We show how seque
 ntial tests can obtain a strictly better performance compared to fixed len
 gth tests in this setting.\nArbitrarily Varying Channels (AVC's) model cha
 nnels which can vary with time in an arbitrary way during the transmission
 . We study the problem of distinguishing between two AVC's where the trans
 mitter (i) is deterministic\, (ii) may privately randomize\, and (iii) sha
 res randomness with the detector.\nIn many practical hypothesis testing pr
 oblems\, our hypotheses might not exactly model the observed data. In such
  a situation\, we would like our test to output the hypothesis which is cl
 oser to the true distribution of the underlying data. It turns out that th
 is is possible only when the hypotheses are not too close. We give a lower
  bound on the optimal separation when the closeness is measured in terms o
 f the Hellinger distance. \nObtaining bounds on the expected generalizati
 on error of a machine learning algorithm is an important problem. We obtai
 n a family of Rényi divergence-based bounds that recover some of the exis
 ting bounds as a special case. Also\, for certain values of the Rényi par
 ameter\, they can be tighter than the existing bounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1575
DTSTART;TZID=Asia/Kolkata:20250704T110000
DTEND;TZID=Asia/Kolkata:20250704T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1578
DTSTAMP:20250703T094715Z
SUMMARY:Supercritical Tradeoffs in Resolution
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nTr
 adeoffs in propositional proof complexity typically involve two parameters
  (e.g.\, size\, width\, depth) and exhibit a CNF for which both of these p
 arameters can be made small separately\, but keeping one parameter small n
 ecessarily makes the other parameter big. Typically\, the lower bound on t
 he other parameter is close to the trivial upper bound on that parameter.\
 nIn a supercritical tradeoff\, keeping one parameter small implies a lower
  bound on the other parameter which is significantly larger than the trivi
 al upper bound. The first such supercritical tradeoff for resolution was e
 xhibited by Razborov\, for the parameters width and tree-size. Since then 
 there has been active research on finding more supercritical tradeoffs.\nW
 e shall describe the first supercritical tradeoff found by Razborov: there
  exists a CNF which has a refutation of width k\, but any tree-like refuta
 tion of width $n^{1-epsilon}/k$ must have size $exp(n^k)$. (The trivial up
 per bound for tree-like size is $exp(n)$)\n
URL:https://www.tcs.tifr.res.in/web/events/1578
DTSTART;TZID=Asia/Kolkata:20250704T160000
DTEND;TZID=Asia/Kolkata:20250704T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1560
DTSTAMP:20250701T052748Z
SUMMARY:Approximating Dasgupta Cost of Clusterable Graphs in Sublinear Time
DESCRIPTION:Speaker: Akash Kumar (IIT Bombay)\n\nAbstract: \nIn a 2002 work
 \, Goldreich and Ron gave sublinear time algorithms for testing graph expa
 nsion. In 2015\, Czumaj\, Peng\, and Sohler extended these ideas to test 
 -clusterability in roughly  time. However\, no sublinear time algorithms
  are known that give any information about the cluster structure of a -cl
 usterable graph. That is\, no such algorithms are known for understanding 
 how clusters connect to each other. As a simple example\, one may wonder 
 whether it is possible to locally distinguish between the "cluster graph" 
 forming a line from a cluster graph which forms a clique.\nIn this talk\, 
 I will present sublinear time algorithms for estimating the hierarchical c
 luster structure of -clusterable graphs. The measure we use is Dasgupta c
 ost\, which is a standard way to evaluate hierarchical clustering. Our mai
 n result is a sublinear time algorithm that approximates the Dasgupta cost
  of a -clusterable graph using a small number of randomly chosen seed ver
 tices with known cluster labels.\nIn particular\, I will describe an algor
 ithm that gives an  approximation to the Dasgupta cost of  in roughly
   time\, using about  seeds. This can be viewed as a sublinear time si
 mulation of the algorithm of Charikar and Chatziafratis (SODA 2017) on clu
 sterable graphs.\nThis is joint work with Michael Kapralov\, Silvio Lattan
 zi\, Aida Mousavifar\, and Weronika Kaminska.\nShort Bio:Akash Kumar is a 
 James R. Isaac Chair Assistant Professor in the Department of Computer Sci
 ence and Engineering at IIT Bombay\, where he has been on the faculty sinc
 e December 2022. His research interests are in spectral graph theory and p
 roperty testing. He is also one of the co-editors of the Property Testing 
 Blog\, where besides sublinear algorithms\, he enjoys writing about recent
  developments in topics such as Boolean functions and Markov chains.\n
URL:https://www.tcs.tifr.res.in/web/events/1560
DTSTART;TZID=Asia/Kolkata:20250708T160000
DTEND;TZID=Asia/Kolkata:20250708T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1571
DTSTAMP:20250701T052316Z
SUMMARY:Scheduling for AoI: Distributed Protocols\, Correlated Sources\, an
 d Non-Uniform Update Sizes
DESCRIPTION:Speaker: Vishrant Tripathi (Purdue University\, USA)\n\nAbstrac
 t: \nI will cover three of our recent works on age optimal scheduling prob
 lems in wireless networks. First\, I will discuss how to extend the perfor
 mance guarantees of centralized max-weight style protocols to distributed 
 CSMA style protocols in the AoI setting. Second\, I will introduce a corre
 lated monitoring problem\, for which I will establish that simple AoI sche
 duling policies are nearly optimal. Third\, I will discuss how to extend m
 ax-weight style Lyapunov policies to a setting where sources send differen
 tly sized updates. Together\, the three works tackle open questions in wir
 eless scheduling for real-time applications.\nShort Bio:\nVishrant Tripath
 i is an Assistant Professor in the ECE department at Purdue University\, w
 here he leads the Multi-Agent Intelligent Networks (MAIN) group. His resea
 rch interests lie in the optimization of networks - with application areas
  including multi-agent robotics\, networked control\, federated learning\,
  and edge computing. Prior to this\, he obtained a Ph.D. in the EECS depar
 tment at MIT\, working with Prof. Eytan Modiano. He has also spent time wo
 rking on data-center network optimization at Google.\n
URL:https://www.tcs.tifr.res.in/web/events/1571
DTSTART;TZID=Asia/Kolkata:20250710T160000
DTEND;TZID=Asia/Kolkata:20250710T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1586
DTSTAMP:20250901T061028Z
SUMMARY:$n^{1.62}$ upper bound of the Hurwitz Problem
DESCRIPTION:Speaker: Soham Chatterjee (TIFR)\n\nAbstract: \nIn this talk we
  will discuss the Hurwitz problem which asks: Given $n$\, upper bound the 
 number $s$ such that $\\left(\\sum_{i=1}^nx_i^2\\right)\\left(\\sum_{i=1}^
 ny_i^2\\right)=\\sum_{k=1}^s f_k^2$ where $x_i\,y_i$'s are variables and $
 f_k=\\bar{x}^TH_k\\bar{y}$\, $H_k\\in\\mathbb{C}^{n\\times n}$. There is a
  trivial upper bound of $s=n^2$ by treating all possible $x_i^2y_j^2$ as b
 ilinear forms. Previously a $O(n^2/\\log n)$ upper bound was shown using H
 urwitz-Radon theorem. In this paper we will show a better bound of $O(n^{1
 .62})$. A specific motivation for this problem comes from arithmetic circu
 it complexity. Wigderson\, Yehudayoff and Hrubesh have shown that a superl
 inear lower bound on $s$ of the form $\\Omega(n^{1+\\epsilon})$\, $\\epsil
 on > 0$\, translates to an exponential circuit lower bound in the non-comm
 utative setting for the degree four polynomial $ID_n=\\sum_{i\,j\\in [n]}x
 _iy_jx_iy_j$.\n
URL:https://www.tcs.tifr.res.in/web/events/1586
DTSTART;TZID=Asia/Kolkata:20250711T160000
DTEND;TZID=Asia/Kolkata:20250711T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1582
DTSTAMP:20250714T043955Z
SUMMARY:Mixing Times for Countable State Markov Chains: A case study of the
  Erlang-C queue
DESCRIPTION:Speaker: Siva Theja Maguluri (Georgia Institute of Technology)\
 n\nAbstract: \nLast few years have seen rapid developments in the mathemat
 ical tools for studying mixing times of Markov chains. However\, most of t
 he focus has been on finite-state Markov chains. Several engineering probl
 ems involve study of countable state Markov chains. Most popular examples 
 are queueing systems that are used to model various resource allocation pr
 oblems in networks\, data centers\, ride-hailing etc. In this work\, we fo
 cus on the Erlang-C system (also known as M/M/n queue)\, and bound the Chi
 -square distance between the finite time queue length distribution and the
  stationary distribution for a finite number of servers. We then use these
  bounds to study the behavior in the many-server heavy-traffic asymptotic 
 regimes. The Erlang-C model exhibits a phase transition at the so-called H
 alfin-Whitt regime. We show that our mixing rate matches the limiting beha
 vior in the Super-Halfin-Whitt regime\, and matches up to a constant facto
 r in the Sub-Halfin-Whitt regime.We obtain these results using the Lyapuno
 v-Poincaré approach\, where we first carefully design a Lyapunov function
  to obtain a negative drift outside a finite set. Within the finite set\, 
 we develop different strategies depending on the properties of the finite 
 set to get a handle on the mixing behavior via a local Poincaré inequalit
 y. A key aspect of our methodological contribution is in obtaining tight g
 uarantees in these two regions\, which when combined give us tight mixing 
 time bounds. We believe that this approach is of independent interest for 
 studying mixing in reversible countable-state Markov chains more generally
 \, and will serve as a stepping stone towards understanding the transient 
 behavior of more general queueing systems.\nShort Bio:Siva Theja Maguluri 
 is Fouts Family Early Career Professor and an Associate Professor in the H
 . Milton Stewart School of Industrial and Systems Engineering at Georgia T
 ech. He obtained his Ph.D. and MS in ECE as well as MS in Applied Math fro
 m UIUC\, and B.Tech in Electrical Engineering from IIT Madras. His researc
 h interests span the areas of Control\, Optimization\, Algorithms and Appl
 ied Probability. In particular\, he works on Reinforcement Learning theory
 \, scheduling\, resource allocation and revenue optimization problems that
  arise in a variety of systems. His research and teaching are recognized t
 hrough several awards including the  “Best Publication in Applied P
 robability award\, NSF CAREER award\, second place award at INFORMS JFIG b
 est paper competition\, Student best paper award at IFIP Performance\, CTL
 /BP Junior Faculty Teaching Excellence Award\, and “Student Recognit
 ion of Excellence in Teaching: Class of 1934 CIOS Award.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1582
DTSTART;TZID=Asia/Kolkata:20250714T110000
DTEND;TZID=Asia/Kolkata:20250714T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1551
DTSTAMP:20250624T110016Z
SUMMARY:Near-Optimal Private Learning with Correlated Noise Mechanisms
DESCRIPTION:Speaker: Krishna Pillutla (IIT Madras)\n\nAbstract: \n\nDiffere
 ntially private (DP) learning algorithms inject noise into the learning pr
 ocess. While the most common private learning algorithm\, DP-SGD\, adds in
 dependent Gaussian noise in each iteration\, recent empirical work has sho
 wn empirically that introducing temporal (anti-)correlations in the noise 
 can greatly improve their utility. I will present two theoretical aspects 
 of these correlated noise mechanisms.\n \nFirst\, I will describe how to 
 attain provably near-optimal  (up to log factors) runtime to calculate te
 mporally correlated noise. The key step in the algorithm design relies on 
 a rational approximation to the square root function.  Second\, I will de
 monstrate an exponential improvement from using correlated noise for line
 ar regression with tight matching upper and lower bounds. In both cases\
 , experiments on private deep learning validate the theoretical claims.
 \n \nBased on joint work (FOCS '24\, ICLR '24) with Chris Choquette\,
  Krishnamurthy Dvijotham\, Arun Ganesh\, Brendan McMahan\, Thomas Stein
 ke\, Abhradeep Guha Thakurta\, and a recent monograph.\nShort Bio:Krishna
  Pillutla is an assistant professor and the Narayanan Family Foundation Fe
 llow at the Wadhwani School of Data Science and AI at IIT Madras in India.
  Previously\, he has been a visiting researcher (postdoc) at Google Resear
 ch in the Federated Learning team. He obtained his Ph.D. at the University
  of Washington\, M.S. from Carnegie Mellon University\, and B.Tech. from 
 IIT Bombay.\nKrishna's research has been recognized by a NeurIPS outstandi
 ng paper award (2021)\, a JP Morgan Ph.D. fellowship (2019-20)\, and two A
 merican Statistical Association (ASA) Student Paper Award Honorable Mentio
 ns.\n
URL:https://www.tcs.tifr.res.in/web/events/1551
DTSTART;TZID=Asia/Kolkata:20250715T160000
DTEND;TZID=Asia/Kolkata:20250715T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1583
DTSTAMP:20250715T052505Z
SUMMARY:A Theory for Computing with SAT Solvers: What's the Power of a Sati
 sfying Assignment?
DESCRIPTION:Speaker: Kuldeep Meel (Georgia Institute of Technology)\n\nAbst
 ract: \nThe past two decades have witnessed dramatic improvements in SAT s
 olving\, enabling today's solvers to handle problems involving millions of
  variables. Motivated by the power of SAT solvers\, there is a growing int
 erest in tackling problems that lie in higher classes of the polynomial hi
 erarchy\, wherein NP calls are to be replaced by SAT solvers in practice. 
 The complexity of such algorithms is measured in terms of calls to NP orac
 les. However\, SAT solvers are not mere decision oracles: they also provid
 e a satisfying assignment when the formula is satisfiable. Therefore\, a t
 heory based on NP oracles is limiting\, and there is a need for a theory t
 hat takes into account the power of SAT solvers. In this talk\, I will dis
 cuss how such consideration leads to new algorithms and new lower bounds i
 n the context of two fundamental problems: model counting and sampling.\nB
 ased on joint work (LICS-22 and ICALP-23) with Diptarka Chakaraborty\, Sou
 rav Chakraborty\, Remi Delannoy\, and Gunjan Kumar.\nShort Bio:Kuldeep Mee
 l holds Stephen Fleming Early-Career Associate Professorship in the School
  of Computer Science at GeorgiaTech\, and an Associate Professor at the Un
 iversity of Toronto (on leave). His research interests lie at the intersec
 tion of Formal Methods and Artificial Intelligence. He is a recipient of t
 he 2022 ACP Early Career Researcher Award\, the 2019 NRF Fellowship for AI
 \, and was named AI's 10 to Watch by IEEE Intelligent Systems in 2020. His
  research program's recent recognitions include the 2023 CACM Research Hig
 hlight Award\, 2022 ACM SIGMOD Research Highlight\, IJCAI-22 Early Career 
 Spotlight\, Distinguished Paper Award at CAV-23\, "Best Papers of CAV" (20
 20 and 2022) special issue in FMSD journal\, Best Paper Award nominations 
 at ICCAD-21 and DATE-23\, 1st Place in Model Counting Competition (2020 an
 d 2022). He is passionate about teaching\, and most proud of being recipie
 nt of university-level Annual Teaching Excellence Awards in 2022 and 2023.
 \n
URL:https://www.tcs.tifr.res.in/web/events/1583
DTSTART;TZID=Asia/Kolkata:20250717T110000
DTEND;TZID=Asia/Kolkata:20250717T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1591
DTSTAMP:20250717T043311Z
SUMMARY:Good prophets know when the end is near
DESCRIPTION:Speaker: Nishant Das (TIFR)\n\nAbstract: \nWe consider a class 
 of online decision-making problems with exchangeable actions\, where in ea
 ch period a controller is presented an input type drawn from some stochast
 ic arrival process and must choose an action\, and the final objective dep
 ends only on the aggregate type-action counts. Such a framework encapsulat
 es many online stochastic variants of common optimization problems with kn
 apsack\, bin packing and generalized assignment as canonical examples. In 
 such settings\, we study a natural model-predictive control algorithm. We 
 introduce general conditions under which this algorithm obtains uniform ad
 ditive loss (independent of the horizon) compared to an optimal solution w
 ith full knowledge of arrivals. Our condition builds on the compensated co
 upling technique of Vera and Banerjee\, providing a unified view of how un
 iform additive loss arises as a consequence of the geometry of the underly
 ing decision-making problem.Our characterization allows us to derive unifo
 rm-loss algorithms for several new settings\, including the first such alg
 orithm for online stochastic bin-packing. It also lets us study the effect
  of other modeling assumptions\, including choice of horizon\, batched dec
 isions\, and limited computation. In particular\, we show that our conditi
 on is fulfilled by the above-mentioned problems when the end of the time-h
 orizon is known sufficiently long before the end. In contrast\, if at a la
 te stage\, there is still uncertainty about the end of the time horizon we
  show that such uniform loss guarantees are impossible to achieve. We demo
 nstrate the performance of our algorithm via large-scale experiments on re
 al and synthetic data.\nGood prophets know when the end is near by Daniel 
 Freund\, Siddhartha Banerjee :: SSRN\nDaniel Freund Massachusetts Institut
 e of Technology (MIT) - Sloan School of Management\nSiddhartha Banerjee Co
 rnell University - School of Operations Research and Information Engineeri
 ng\n
URL:https://www.tcs.tifr.res.in/web/events/1591
DTSTART;TZID=Asia/Kolkata:20250717T160000
DTEND;TZID=Asia/Kolkata:20250717T180000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1592
DTSTAMP:20250717T044959Z
SUMMARY:A General Identification Algorithm For Data Fusion Problems Under S
 ystematic Selection
DESCRIPTION:Speaker: Spandan Poddar (TIFR)\n\nAbstract: \nIdentification of
  causal effects can be hampered by confounding\, selection bias\, and othe
 r complications. Data fusion is one approach to addressing these difficult
 ies\, through the inclusion of auxiliary data on the population of interes
 t. Such data may measure a different set of variables\, or be obtained und
 er different experimental or observational conditions than the primary dat
 aset. In particular\, selection of experimental units into different datas
 ets may be systematic\; similar difficulties are encountered in missing da
 ta problems. However\, existing methods for combining datasets either do n
 ot consider this issue\, or assume simple selection mechanisms. In this pa
 per\, we propose a general approach\, based on graphical causal models\, f
 or causal inference from data on the same population that is obtained unde
 r different experimental conditions. Our framework allows both arbitrary u
 nobserved confounding\, and arbitrary selection processes into different e
 xperimental regimes in our data. We describe how systematic selection proc
 esses may be organized into a hierarchy similar to censoring processes in 
 missing data: selected completely at random\, selected at random\, and sel
 ected not at random. Finally\, we provide a novel general identification a
 lgorithm for interventional distributions in this setting.\nAuthors: Jaron
  Jia Rong Lee\, AmirEmad Ghassami\, Ilya Shpitser \nProceedings of the Fo
 rtieth Conference on Uncertainty in Artificial Intelligence\, PMLR 244:218
 8-2204\, 2024.\nA general identification algorithm for data fusion problem
 s under systematic selection | Proceedings of the Fortieth Conference on U
 ncertainty in Artificial Intelligence\n
URL:https://www.tcs.tifr.res.in/web/events/1592
DTSTART;TZID=Asia/Kolkata:20250718T094500
DTEND;TZID=Asia/Kolkata:20250718T114500
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1584
DTSTAMP:20250717T064935Z
SUMMARY:Specification-Guided Reinforcement Learning
DESCRIPTION:Speaker: Suguman Bansal (Georgia Institute of Technology)\n\nAb
 stract: \nReinforcement Learning (RL) is being touted to revolutionize the
  way we design systems. However\, a key challenge to reaching that holy gr
 ail comes from the lack of guarantees that the synthesized systems offer. 
 Logic and formal reasoning can address some of these issues ... or can the
 y? In this talk\, I will cover recent progress in using logical specificat
 ions in RL and discuss the challenges it faces moving forward.\n \nShort 
 Bio:Suguman Bansal is a is an assistant professor in the School of Compute
 r Science at Georgia Institute of Technology. Her research interests lie a
 t the intersection of Artificial Intelligence and Programming Languages. S
 pecifically\, she works on developing tools and techniques to improve the 
 quality of automated verification and synthesis of computational systems. 
 Her recent work concerns providing formal guarantees about learning-enable
 d systems with a focus on Reinforcement Learning.\nShe received her Ph.D. 
 (2020) and M.S. (2016) in Computer Science from Rice University\, and B.S.
  (with Honors) degree (2014) in Mathematics and Computer Science from Chen
 nai Mathematical Institute. She is the recipient of the Amazon Research Aw
 ard 2024\, ATVA Best Paper Award 2023\, MIT EECS Rising Stars 2021 and 201
 8\, Future Faculty Fellowship 2019\, Andrew Ladd Fellowship 2016\, and a G
 old Medal at the ACM Student Research Competition at POPL 2016.\n
URL:https://www.tcs.tifr.res.in/web/events/1584
DTSTART;TZID=Asia/Kolkata:20250718T110000
DTEND;TZID=Asia/Kolkata:20250718T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1590
DTSTAMP:20250717T055431Z
SUMMARY:Approximate Problems for Finite Transducers
DESCRIPTION:Speaker: Saina Sunny (IIT Goa)\n\nAbstract: \nFinite (word) sta
 te transducers extend finite state automata by defining a binary relation 
 over finite words\, called rational relation. If the rational relation is 
 the graph of a function\, this function is said to be rational. The class 
 of sequential functions is a strict subclass of rational functions\, defin
 ed as the functions recognised by input-deterministic finite state transdu
 cers. The class membership problems between those classes are known to be 
 decidable. In this talk\, I present approximate versions of these problems
  and show they are decidable as well. This includes the approximate functi
 onality problem\, which asks whether given a rational relation (by a trans
 ducer)\, is it close to a rational function\, and the approximate determin
 isation problem\, which asks whether a given rational function is close to
  a sequential function. Closeness is measured using a notion of distance b
 etween functions or relations.\n
URL:https://www.tcs.tifr.res.in/web/events/1590
DTSTART;TZID=Asia/Kolkata:20250718T160000
DTEND;TZID=Asia/Kolkata:20250718T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1548
DTSTAMP:20250703T044924Z
SUMMARY:Dynamic optimality conjecture and related open problems
DESCRIPTION:Speaker: Manoj Gupta (IIT Gandhinagar)\n\nAbstract: \nA binary 
 search tree (BST) is dynamically optimal if it processes any search sequen
 ce X in time within a constant factor of the offline optimum. Sleator and 
 Tarjan (JACM 1985) famously conjectured that the Splay Tree achieves dynam
 ic optimality—this is the dynamic optimality conjecture. Despite its sig
 nificance\, progress has been limited. More recently\, Demaine et al. (SOD
 A 2009) proposed another BST\, GREEDY\, also conjectured to be dynamically
  optimal. The central goal remains: prove that either Splay Tree or GREEDY
  achieves dynamic optimality. In this talk\, we'll explore recent advances
  and highlight key open problems.\nShort Bio:\nManoj Gupta is an Associate
  Professor at IIT Gandhinagar. He received his Ph.D. from IIT Delhi. His r
 esearch interests are Dynamic\, Fault-tolerant\, and Graph Algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1548
DTSTART;TZID=Asia/Kolkata:20250722T160000
DTEND;TZID=Asia/Kolkata:20250722T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1593
DTSTAMP:20250717T105949Z
SUMMARY:Six Candidates Suffice to Win a Voter Majority
DESCRIPTION:Speaker: Vivek Karunakaran (TIFR)\n\nAbstract: \nA cornerstone 
 of social choice theory is Condorcet's paradox which says that in an elect
 ion where n voters rank m candidates it is possible that\, no matter which
  candidate is declared the winner\, a majority of voters would have prefer
 red an alternative candidate. Instead\, can we always choose a small commi
 ttee of winning candidates that is preferred to any alternative candidate 
 by a majority of voters?Elkind\, Lang\, and Saffidine raised this question
  and called such a committee a Condorcet winning set. They showed that win
 ning sets of size 2 may not exist\, but sets of size logarithmic in the nu
 mber of candidates always do. In this work\, the authors show that Condorc
 et winning sets of size 6 always exist\, regardless of the number of candi
 dates or the number of voters. The proof uses the probabilistic method and
  the minimax theorem\, inspired by recent work on approximately stable com
 mittee selection.\nAuthors: Moses Charikar\, Alexandra Lassota\, Prasann
 a Ramakrishnan\, Adrian Vetta\, Kangning Wang\n[2411.03390] Six Candidat
 es Suffice to Win a Voter Majority\n
URL:https://www.tcs.tifr.res.in/web/events/1593
DTSTART;TZID=Asia/Kolkata:20250723T140000
DTEND;TZID=Asia/Kolkata:20250723T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1594
DTSTAMP:20250723T100826Z
SUMMARY:Adversarial Bandits with Knapsacks
DESCRIPTION:Speaker: Aakash Ghosh (TIFR)\n\nAbstract: \nWe consider Bandit
 s with Knapsacks (henceforth\, BwK)\, a general model for multi-armed ba
 ndits under supply/budget constraints. In particular\, a bandit algorithm 
 needs to solve a well-known knapsack problem: find an optimal packing of 
 items into a limited-size knapsack. The BwK problem is a common generaliza
 tion of numerous motivating examples\, which range from dynamic pricing to
  repeated auctions to dynamic ad allocation to network routing and schedul
 ing. While the prior work on BwK focused on the stochastic version\, we pi
 oneer the other extreme in which the outcomes can be chosen adversarially.
  This is a considerably harder problem\, compared to both the stochastic v
 ersion and the “classic” adversarial bandits\, in that regret minimiza
 tion is no longer feasible. Instead\, the objective is to minimize the co
 mpetitive ratio: the ratio of the benchmark reward to algorithm’s reward
 .\n \nWe design an algorithm with competitive ratio O(log T) relative t
 o the best fixed distribution over actions\, where T is the time horizon
 \; we also prove a matching lower bound. The key conceptual contribution i
 s a new perspective on the stochastic version of the problem. We suggest a
  new algorithm for the stochastic version\, which builds on the framework 
 of regret minimization in repeated games and admits a substantially simple
 r analysis compared to prior work. We then analyze this algorithm for the 
 adversarial version\, and use it as a subroutine to solve the latter.\n \
 nAuthors: Nicole Immorlica\, Karthik Sankararaman\, Robert Schapire\, A
 leksandrs SlivkinsAuthors Info & Claims\nJournal of the ACM\, Volume 69
 \, Issue 6\nArticle No.: 40\, Pages 1 - 47\nhttps://doi.org/10.1145/3
 557045\n
URL:https://www.tcs.tifr.res.in/web/events/1594
DTSTART;TZID=Asia/Kolkata:20250723T163000
DTEND;TZID=Asia/Kolkata:20250723T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1595
DTSTAMP:20250717T110541Z
SUMMARY:Universal Optimality of Dijkstra using Fibonacci Like Working Sets
DESCRIPTION:Speaker: Soham Chatterjee (TIFR)\n\nAbstract: \nIn this talk we
  will show that the good Dijkstra's shortest path algorithm is universally
  optimal in both running time and number of comparisons when combined with
  a sufficiently efficient heap data structure namely Fibonacci Like priori
 ty queue with the working set property. We will prove that the working set
  property guarantees universal optimality for the problem of ordering vert
 ices by their distance from the source vertex. The new heap data structure
  with working set property takes advantage of locality in heap operation w
 hich results in matching the optimal bounds of Fibonacci heaps but also pr
 ovides the beyond-worst-case guarantee that the cost of extracting the min
 imum element is merely logarithmic in the number of elements inserted afte
 r it instead of logarithmic in the number of elements in the heap. This ma
 kes the extraction of recently added elements cheaper.\n
URL:https://www.tcs.tifr.res.in/web/events/1595
DTSTART;TZID=Asia/Kolkata:20250724T150000
DTEND;TZID=Asia/Kolkata:20250724T160000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1588
DTSTAMP:20250714T071802Z
SUMMARY:Self-Improvement for Circuit-Analysis Problems
DESCRIPTION:Speaker: Shubham Bhardwaj (TIFR)\n\nAbstract: \nIn this talk\, 
 we'll explore a self-improvement phenomenon for Circuit-SAT\, $\\#$Circuit
 -SAT and its fully quantified variants. We'll see that even modest improve
 ments over brute-force algorithms for large circuits—where satisfiabilit
 y is polynomial-time solvable—can be amplified into significant speedups
  for smaller\, subexponential-size circuits. The arguments will also work 
 for a variety of models solving circuit-analysis problems\, including non-
 uniform circuits and randomized models of computation.\n
URL:https://www.tcs.tifr.res.in/web/events/1588
DTSTART;TZID=Asia/Kolkata:20250725T140000
DTEND;TZID=Asia/Kolkata:20250725T160000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1598
DTSTAMP:20250725T050343Z
SUMMARY:The HDX construction of Kaufman-Oppenheim
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR)\n\nAbstract: \nWe will look at
  the high-dimensional expander construction and analysis by Kaufman and Op
 penheim (rather\, the exposition by Harsha and Saptharishi). Both the cons
 truction and analysis are elementary and based on simple group theory. I w
 on't assume familiarity with HDXs.\n
URL:https://www.tcs.tifr.res.in/web/events/1598
DTSTART;TZID=Asia/Kolkata:20250725T160000
DTEND;TZID=Asia/Kolkata:20250725T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1589
DTSTAMP:20250725T093050Z
SUMMARY:Counting Problems in Graphical Models
DESCRIPTION:Speaker: Vidya Sagar Sharma (TIFR)\n\nAbstract: \nA graphical m
 odel is a probabilistic model that uses a graph to represent conditional i
 ndependence relations among random variables. We study acyclic directed gr
 aphical models\, where a directed acyclic graph (DAG) is used to represent
  both conditional independence and causal relationships. Multiple DAGs can
  represent the same set of conditional independence relations\; such DAGs 
 are called Markov equivalent and belong to the same equivalence class\, ca
 lled a Markov equivalence class (MEC)\, which is graphically represented b
 y the union of the DAGs it contains. Many combinatorial problems related t
 o MECs have been studied in the literature. One such problem is: given the
  graphical representation of an MEC\, compute its size. In a generalizatio
 n of this problem\, we are also given background knowledge in the form of 
 a set of directed edges. A DAG in the MEC is consistent with the backgroun
 d knowledge if the background knowledge is a subset of its directed edges\
 , and the goal is to count such DAGs. Another important problem is: given 
 an undirected graph\, count the number of MECs whose skeleton is the same 
 as the undirected graph.\n \nWienöbst et al. show that counting backgrou
 nd knowledge-consistent DAGs in an MEC is #P-hard. In this talk\, we prese
 nt an FPT algorithm for this problem\, along with an FPT algorithm for cou
 nting MECs with a given skeleton. We further provide a faster FPT algorith
 m when the input graph is chordal\, and a polynomial-time algorithm when t
 he input graph is a tree.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1589
DTSTART;TZID=Asia/Kolkata:20250730T140000
DTEND;TZID=Asia/Kolkata:20250730T163000
LOCATION:Hybrid Mode (A-201)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1599
DTSTAMP:20250730T042810Z
SUMMARY:Hardness of Computing Graph State Distance
DESCRIPTION:Speaker: Vatsal Jha (Purdue University)\n\nAbstract: \nThe prob
 lem of computing the distance of classical error-correcting codes was show
 n to be NP-hard by Alexander Vardy in 1997. Recently\, Kapshikar and Kundu
  extended this result by proving the hardness of computing distances of qu
 antum codes. In this talk\, I will prove the hardness of computing the min
 imum distance of a specific class of quantum codes defined using graphs\, 
 referred to as graph states. Graph states play a key role in various quan
 tum applications\, including cryptography and communication. As a further 
 application of our techniques\, we also prove the hardness of computing th
 e distance of classical codes with constant rate in the interval (0\,1/2]
 .\nThis work is in collaboration with Elena Grigorescu (University of Wate
 rloo) and Eric Samperton (Purdue University).\nShort Bio:I am currently a 
 PhD student in the Department of Computer Science at Purdue University\, j
 ointly advised by Elena Grigorescu and Eric Samperton. My research interes
 ts lie in Coding Theory (both classical and quantum) and the Analysis of B
 oolean Functions.\n
URL:https://www.tcs.tifr.res.in/web/events/1599
DTSTART;TZID=Asia/Kolkata:20250731T160000
DTEND;TZID=Asia/Kolkata:20250731T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1601
DTSTAMP:20250731T071153Z
SUMMARY:Counting in constrained worlds and the Fibonacci Trick
DESCRIPTION:Speaker: Aindrila Rakshit (TIFR)\n\nAbstract: \nMany graph-theo
 retic counting problems remain intractable (indeed #P-complete) despite ad
 ditional constraints on their structural properties\, like planarity\, bip
 artiteness\, and low degree\, even though their decision counterparts migh
 t be easy. This talk explores Salil Vadhan’s framework for proving #P-co
 mpleteness of problems like #Matchings\, #VertexCovers\, and #Monotone2CNF
  even on planar\, low-degree\, and regular graphs. A new interpolation bas
 ed reduction technique that uses Fibonacci-style gadgets to preserve struc
 ture like constant degree\, during reductions is used to prove these resul
 ts. Based on: The Complexity of Counting in Sparse\, Regular\, and Planar 
 Graphs\, Salil P. Vadhan (https://doi.org/10.1137/S0097539797321602).\n \
 n
URL:https://www.tcs.tifr.res.in/web/events/1601
DTSTART;TZID=Asia/Kolkata:20250801T160000
DTEND;TZID=Asia/Kolkata:20250801T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1580
DTSTAMP:20250731T100935Z
SUMMARY:Quality Control on Random Graphs in Sublinear Time
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Poulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nMany algorithms have lately been
  designed to work well on average (i.e.\, on inputs coming from some distr
 ibution D)\, but then when running this algorithm on a specific input x\, 
 we are forced to ask the question — can we really trust the algorithm on
  this input?\nIn this work we define a class of problems — that we call 
 quality control problems\, whose definition allows the algorithm to exploi
 t the randomness of instances\, while still being safe to use on a specifi
 c input. A quality control problem is given by a pair (rho\,D) where rho i
 s a real valued quality parameter and D a distribution on inputs. We assum
 e that inputs from D are "high quality" (i.e.\, have rho(x) close to 1) wi
 th high probability. An algorithm A is said to solve the problem if it sat
 isfies (1) Completeness - it accepts inputs from D w.h.p. and (2) Soundnes
 s - if rho(x) is far from 1\, it rejects (w.h.p. over internal randomness)
 . [This definition is inspired by Feige's work on refutation of random CSP
 s and also by Rubinfeld and Vasilian's work on testable learning.] So the 
 algorithm does not accept every high quality input\, but does accept most 
 of them\; while rejecting every poor quality input w.h.p.\nQuality control
  problems get technically interesting when the condition "rho(x) ~= 1" is 
 not easily certifiable. We consider a natural class of such problems - nam
 ely counting constant sized subgraphs in an Erdos-Renyi random graph (G(n\
 ,p)) where edges appear independently with probability p. Among our result
 s we give quality control algorithms that make (1/p)^O(k) queries to the a
 djacency matrix of a graph G to confirm that the number of k-cliques is ro
 ughly the expected number in G(n\,p). In contrast it is known that a subli
 near algorithm solving this problem on worst case inputs would require (1/
 p)^Theta(k^2) queries. \nOur proofs highlight the nice composability feat
 ures of quality control problems while also invoking tools from probabilit
 y theory and quasirandomness of graphs that may be of general interest.\nJ
 oint work with Cassandra Marcussen (Harvard) and Ronitt Rubinfeld (MIT).\n
 Short Bio: Madhu Sudan is Gordon McKay Professor at Harvard's John A. Paul
 son School of Engineering and Applied Sciences. He got his B.Tech. from II
 T Delhi and Ph.D. from UC Berkeley and  previously held positions at IBM 
 Research\, MIT\, and Microsoft Research. His research focuses on the mathe
 matical foundations of communication and computation in general\, and in p
 articular on questions about probabilistically checkable proofs\, list dec
 oding of error correcting codes\, property testing\, sublinear time algori
 thms and communication in the presence of uncertainty. \n
URL:https://www.tcs.tifr.res.in/web/events/1580
DTSTART;TZID=Asia/Kolkata:20250805T160000
DTEND;TZID=Asia/Kolkata:20250805T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1603
DTSTAMP:20250807T084235Z
SUMMARY:Approximation of Mixed Volumes of Convex Bodies
DESCRIPTION:Speaker: Sourav  Roy (TIFR)\n\nAbstract: \nIn the area of conve
 x geometry\, the approximation of volumes of convex bodies is an active ar
 ea of research. Let us recall that the Steiner formula for a compact conve
 x body K and the Euclidean unit ball B in n-dimensional Euclidean space al
 ong with a non-negative scalar ``c" \, is a polynomial in ``c" of degree n
 \, and the  i-th coefficient of $c^{n-i}$ are known as the i-th mixed vol
 ume of K+cB. In this talk\, I will present a method to approximate the n-d
 imensional measure of mixed volumes of the convex body K+cB\, where K is a
  convex polytope. \n
URL:https://www.tcs.tifr.res.in/web/events/1603
DTSTART;TZID=Asia/Kolkata:20250808T160000
DTEND;TZID=Asia/Kolkata:20250808T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1604
DTSTAMP:20250807T102227Z
SUMMARY:Testing for (algebraic) patterns in data
DESCRIPTION:Speaker: Madhu Sudan (Harvard John A. Poulson School of Enginee
 ring and Applied Sciences)\n\nAbstract: \nThe need to trawl through massiv
 e amounts of data to see if it can reveal some interesting pattern is over
 whelming all sciences. A massive amount of time and computing resources ar
 e often expended looking for patterns in data that have nothing to reveal.
  In modern times\, even expressing the "pattern" that has been found takes
  enormous amounts of time. Is it possible to run quick and dirty tests on 
 data to see if it even contains a pattern of interest\, before actually le
 arning the entire pattern (if one exists)?The field of Property Testing st
 udies exactly this problem—searching for algorithms that Test if some (m
 assive) data satisfies some global Property without looking at all the dat
 a\, or inferring the parameters that explain how the data satisfies the pr
 operty. It was initiated by an accidental discovery by Blum\, Luby and Rub
 infeld in the late 1980s showing that some complex properties could be tes
 ted remarkably efficiently. In the four decades since the original discove
 ry\, the scope of Property Testing has expanded broadly—covering propert
 ies of algebraic\, graph-theoretic\, statistical\, and functional nature\;
  and the resulting techniques have connected the field to combinatorics\, 
 additive number theory\, harmonic analysis\, algebraic geometry\, while ha
 ving applications in complexity theory\, combinatorial optimization and ev
 en extremal graph theory.In this talk\, I will briefly survey some of thes
 e results before focussing on two celebrated results within this field: (1
 ) linearity testing: testing if a multivariate function is actually linear
 \, in constant time independent of the number of variables! And (2) Low-de
 gree testing: extending linearity testing to higher degree polynomials. Ti
 me permitting\, I will mention a recent result with collaborators Prahladh
  Harsha\, Mrinal Kumar and Ramprasad Saptharishi (all from TIFR!)\, giving
  the ultimate dimension reduction result for low-degree testing.\n \nSPEA
 KER INFORMATION: Madhu Sudan is a Gordon McKay Professor in the John A. Pa
 ulson School of Engineering and Applied Sciences at Harvard University\, w
 here he has been since 2015. He is a recipient of the Nevanlinna Prize\, t
 he Infosys Foundation Prize\, and the IEEE Hamming Medal. His research int
 erests revolve around mathematical studies of communication and computatio
 n.\n \nTesting for (algebraic) patterns in data (August 11\, 2025) · Sci
 entific Talks (Indico)\nTIFR Institute Colloquium\n
URL:https://www.tcs.tifr.res.in/web/events/1604
DTSTART;TZID=Asia/Kolkata:20250811T173000
DTEND;TZID=Asia/Kolkata:20250811T183000
LOCATION:Homi Bhabha Auditorium
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1577
DTSTAMP:20250730T043031Z
SUMMARY:Assessing the Quality of Binomial Samplers: A Statistical Distance 
 Framework
DESCRIPTION:Speaker: Sourav Chakraborty (ISI Kolkata)\n\nAbstract: \nRandom
 ized algorithms depend on accurate sampling from probability distributions
 \, as their correctness and performance hinge on the quality of the genera
 ted samples. However\, even for common distributions like Binomial\, exact
  sampling is computationally challenging\,  leading standard library impl
 ementations to rely on heuristics. These heuristics\, while efficient\, su
 ffer from approximation and system representation errors\, causing deviati
 ons from the ideal distribution. Although seemingly minor\, such deviation
 s can accumulate in downstream applica-tions requiring large-scale samplin
 g\, potentially undermining algorithmic guarantees.  We will take a look 
 at this often overlooked issue related to correctness of randomized algori
 thms and have a discussion on what we can do to address this issue?This is
  a joint work with Kuldeep Meel and Uddalok Sarkar. This work will appear 
 in CAV 2025.\nShort Bio:Sourav Chakraborty is a Professor of Computer Scie
 nce at the Indian Statistical Institute (ISI)\, Kolkata. He earned his bac
 helor's degree in Mathematics from Chennai Mathematical Institute in 2003\
 , followed by a Master's (2005) and Ph.D. (2008) in Computer Science from 
 the University of Chicago\, where he studied under the famous mathematicia
 n and computer scientist  Prof. László Babai. He pursued postdoctoral r
 esearch at Technion\, Israel\, and CWI Amsterdam before joining Chennai Ma
 thematical Institute in 2010 and later moving to ISI in 2018. His primary 
 research interests lie in Theoretical Computer Science. \n
URL:https://www.tcs.tifr.res.in/web/events/1577
DTSTART;TZID=Asia/Kolkata:20250812T160000
DTEND;TZID=Asia/Kolkata:20250812T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1605
DTSTAMP:20250814T083700Z
SUMMARY:Equilibrium Computation in the Hotelling-Downs Model of Spatial Com
 petition
DESCRIPTION:Speaker: Soumyajit Pyne (TIFR)\n\nAbstract: \nThe Hotelling-Dow
 ns model is a natural and appealing model for understanding strategic posi
 tioning by candidates in elections. In this model\, voters are distributed
  on a line\, representing their ideological position on an issue. Each can
 didate then chooses as a strategy a position on the line to maximize her v
 ote share. Each voter votes for the nearest candidate\, closest to their i
 deological position. This sets up a game between the candidates\, and we s
 tudy pure Nash equilibria in this game. The model and its variants are an 
 important tool in political economics\, and are studied widely in computat
 ional social choice as well.Despite the interest and practical relevance\,
  most prior work focuses on the existence and properties of pure Nash equi
 libria in this model\, ignoring computational issues. Our work gives algor
 ithms for computing pure Nash equilibria in the basic model. We give three
  algorithms\, depending on whether the distribution of voters is continuou
 s or discrete\, and similarly\, whether the possible candidate positions a
 re continuous or discrete. In each case\, our algorithms return either an 
 exact equilibrium or one arbitrarily close to exact\, assuming existence. 
 We believe our work will be useful\, and may prompt interest\, in computin
 g equilibria in the wide variety of extensions of the basic model as well.
 \nLink to the paper: https://arxiv.org/abs/2412.12523\n
URL:https://www.tcs.tifr.res.in/web/events/1605
DTSTART;TZID=Asia/Kolkata:20250814T171500
DTEND;TZID=Asia/Kolkata:20250814T181500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1596
DTSTAMP:20250811T064833Z
SUMMARY:STCS Annual Symposium 2025
DESCRIPTION:Speaker: \n\nAbstract: \nVisit STCS Annual Symposium 2025 page
  for more details.\n
URL:https://www.tcs.tifr.res.in/web/events/1596
DTSTART;VALUE=DATE:20250818
DTEND;VALUE=DATE:20250820
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1572
DTSTAMP:20250818T065453Z
SUMMARY:Explainability\, Model Surgery\, and Quantum EM: Vignettes in Machi
 ne Learning
DESCRIPTION:Speaker: Chiranjib Bhattacharyya (IISC Banglore)\n\nAbstract: \
 nIn this talk\, I will present three research vignettes spanning explainab
 ility\, model editing\, and quantum generative modeling. First\, I will di
 scuss a compelling problem in explainability that emerged from our experie
 nce deploying XraySetu—a diagnostic service launched during the COVID-19
  pandemic. Second\, I will describe our work on identifying structural com
 ponents for model editing. Notably\, our approach does not require access 
 to the original training data or knowledge of the loss functions used to t
 rain the model. Instead\, it hinges on a novel lower bound on the total va
 riation (TV) distance via witness functions—a result that is of independ
 ent interest and\, for example\, enables upper bounds on the Bayes error r
 ate for the Fisher Discriminant. Finally\, time permitting\, I will presen
 t ongoing work on learning algorithms for generative AI models in a quantu
 m computing setting. In particular\, I will outline our derivation of Mino
 rant Maximization–style algorithms\, in the spirit of Expectation-Maximi
 zation (EM)\, for large-scale transverse-field Ising models.\nShort Bio:\n
 Chiranjib Bhattacharyya is currently Professor in the Department of Comput
 er Science and Automation\, Indian Institute of Science. His research inte
 rests are in foundations of Machine Learning\, Optimisation and their appl
 ications to Industrial problems. He is fellow of Indian Academy of Enginee
 ring\, Indian Academy of Sciences and Asia-Pacific Artificial Intelligence
  Association. He joined the Department of CSA\, IISc\, in 2002 as an Assis
 tant Professor. Prior to joining the Department he was a postdoctoral fell
 ow at UC Berkeley. He holds BE and ME degrees\, both in Electrical Enginee
 ring\, from Jadavpur University and the Indian Institute of Science\, resp
 ectively\, and completed his PhD from the Department of Computer Science a
 nd Automation\, Indian Institute of Science.\n
URL:https://www.tcs.tifr.res.in/web/events/1572
DTSTART;TZID=Asia/Kolkata:20250818T093000
DTEND;TZID=Asia/Kolkata:20250818T103000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1574
DTSTAMP:20250812T100253Z
SUMMARY:Eternal Versions of Vertex Cover and Dominating Set
DESCRIPTION:Speaker: Neeldhara Misra (IIT Gandhinagar)\n\nAbstract: \nMobil
 e guards on the vertices of a graph are used to defend it against an infin
 ite sequence of attacks on either its vertices or its edges. A defense aga
 inst vertex attacks naturally corresponds to maintaining a dominating set\
 , and a defense against edge attacks corresponds to maintaining a vertex c
 over. These games were introduced by Klostermeyer and Mynhardt. \nTo be e
 xplicit\, we are considering two player games --- between players whom we 
 will refer to as the attacker and defender --- on a simple\, undirected gr
 aph G. In the beginning\, the defender can choose to place guards on some 
 of the vertices of G. The attacker's move involves choosing an edge (verte
 x) to attack. The defender is able to defend this attack if she can move t
 he guards along the edges of the graph in such a way that at least one gua
 rd moves along the attacked edge (vertex). If such a movement is not possi
 ble\, then the attacker wins. If the defender can defend the graph against
  an infinite sequence of attacks\, then the defender wins. The minimum num
 ber of guards with which the defender has a winning strategy is called the
  eternal vertex cover (eternal domination) number of the graph G.\nWe will
  explore some structural aspects of these parameters\, with a special focu
 s on relating them to the corresponding static parameters. In particular\,
  we will consider when the eternal vertex cover number coincides with the 
 minimum vertex cover\, and explore a structural characterization on bipart
 ite graphs (based on joint work with Saraswati Nanoti). We will also explo
 re the question of eternal domination on infinite grids (based on joint wo
 rk with Tiziana Calamoneri\, Federico Corò\, Saraswati Girish Nanoti and 
 Giacomo Paesani).\nShort Bio: Neeldhara Misra is a Smt. Amba and Sri. V S
  Sastry Chair Associate Professor of Computer Science and Engineering at t
 he Indian Institute of Technology\, Gandhinagar. She completed her PhD fro
 m the Institute for Mathematical Sciences in 2012 in Theoretical Computer 
 Science\, followed by a post-doc at the Department of Computer Science and
  Automation at IISc. Her research interests include the design and analysi
 s of algorithms for graph optimization problems and computational social c
 hoice. She is also interested in visualizations and other methods to commu
 nicate computational thinking at an elementary level.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1574
DTSTART;TZID=Asia/Kolkata:20250819T093000
DTEND;TZID=Asia/Kolkata:20250819T103000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1573
DTSTAMP:20250812T095604Z
SUMMARY:Games played on asynchronous transition systems
DESCRIPTION:Speaker: Bharat Adsul (IIT Bombay)\n\nAbstract: \nAnalysis of t
 wo-player games played on graphs is central to  reactive synthesis and i
 t has been carried out in much detail. In this talk\, we will explore som
 e natural extensions of these games which are played between a distribute
 d team of processes and an adversarial environment. Many real-life distri
 buted applications can be modelled using them. Our games are played on a 
 network of asynchronous processes modelled as finite-state devices which 
 synchronize on shared actions and support true concurrency. Processes are
  allowed to exchange the entire casual past on shared actions to respond 
 to the environment.\nGiven a distributed game structure and a winning obje
 ctive\, the key algorithmic problem is: whether a distributed winning str
 ategy meeting that objective exists or not. We will discuss some special 
 classes of these games with natural winning objectives such as global saf
 ety\, local parity etc and develop algorithms to solve this key decision
  problem efficiently. Another important concern is: for the affirmative 
 instance of the above problem\, existence of a finite-state distributed w
 inning strategy and its construction. For the above mentioned cases\, we 
 will see an explicit construction of a finite-state distributed winning s
 trategy.\nThis is ongoing work with PhD student Nehul Jain.\nShort Bio:Bha
 rat Adsul is currently a Professor in the Department of Computer Science 
 and Engineering at IIT Bombay. He received his Ph.D. from IIT Bombay in 2
 003 and worked at Chennai Mathematical Institute from 2003 to 2007. His r
 esearch interests are in formal methods with special focus on concurrency
  (automata theory\, logics\, games\, algebraic aspects)\, geometric compl
 exity theory and mathematical programming in general.\n
URL:https://www.tcs.tifr.res.in/web/events/1573
DTSTART;TZID=Asia/Kolkata:20250819T160000
DTEND;TZID=Asia/Kolkata:20250819T170000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1581
DTSTAMP:20250821T094538Z
SUMMARY:Accelerating Gravitational-Wave Inference with Reduced Order Surrog
 ate Models
DESCRIPTION:Speaker: Tousif Islam (University of California Santa Barbara)\
 n\nAbstract: \nWith nearly 100 detections of binary black hole mergers\, g
 ravitational-wave (GW) astronomy is now a data-rich field. Extracting info
 rmation from noisy GW signals requires accurate waveform models that descr
 ibe the radiation emitted during these mergers. The most accurate waveform
 s are generated through numerical relativity (NR)\, which involves solving
  Einstein's equations via large-scale simulations. While NR provides high-
 fidelity data\, each simulation is computationally expensive — often req
 uiring weeks to months of supercomputing time — making it impractical fo
 r real-time detection or Bayesian source characterization.\n \nIn this ta
 lk\, I will present how techniques from nonlinear reduced order modeling 
 — including the Discrete Empirical Interpolation Method — combined wit
 h physics-informed signal decomposition\, enable fast\, accurate surrogate
  models that compress high-dimensional NR waveforms into representations e
 valuable in milliseconds. I will describe the construction pipeline\, key 
 numerical techniques\, and the integration of these surrogates into GW dat
 a analysis. Finally\, I will demonstrate how they are enabling precision a
 strophysical inference at scale.\n \nShort Bio: \nTousif Islam is a Kavli
  Postdoctoral Scholar at the Kavli Institute for Theoretical Physics. His 
 research focuses on high-performance computing\, data science\, and gravit
 ational-wave astronomy\, particularly in building nonlinear reduced order 
 models and Bayesian inference frameworks. Tousif earned his PhD in Computa
 tional Sciences and MS in Data Science from the University of Massachusett
 s Dartmouth in 2023. During his PhD\, he held several competitive research
  fellowships and visiting positions\, including as a Kavli Graduate Fellow
  at KITP (UCSB)\, a predoctoral scholar at the NSF Institute for Pure and 
 Applied Mathematics (IPAM\, UCLA)\, a visiting researcher at the TAPIR gro
 up (Caltech)\, a semester visitor at the NSF Institute for Computational a
 nd Experimental Research in Mathematics (ICERM\, Brown)\, and a GravNet fe
 llow at the Niels Bohr Institute (University of Copenhagen). He holds a BS
 -MS in Physics from IISER Kolkata and was a Long-Term Student Fellow at IC
 TS-TIFR.\n
URL:https://www.tcs.tifr.res.in/web/events/1581
DTSTART;TZID=Asia/Kolkata:20250821T160000
DTEND;TZID=Asia/Kolkata:20250821T170000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1608
DTSTAMP:20250821T044002Z
SUMMARY:Quantum Complexity and Black Holes
DESCRIPTION:Speaker: Sriram Akella (Department of Theoretical Physics\, TIF
 R Mumbai)\n\nAbstract: \nIn recent years\, quantum complexity has emerged 
 as a powerful new tool in the effort to understand black holes. In this ta
 lk\, I will explore some of these exciting developments\, assuming no prio
 r knowledge of quantum physics or gravity. I’ll begin with an introducti
 on to quantum computation and the notion of quantum complexity. I will the
 n present a simple toy model that captures many intriguing features of bla
 ck holes. Through this model\, we’ll see how quantum complexity offers a
  fresh lens on black hole physics. The central message of the talk is that
  quantum complexity isn’t just a mathematical abstraction—it quantifie
 s something fundamentally physical about black holes.\n
URL:https://www.tcs.tifr.res.in/web/events/1608
DTSTART;TZID=Asia/Kolkata:20250822T160000
DTEND;TZID=Asia/Kolkata:20250822T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1607
DTSTAMP:20250821T063058Z
SUMMARY:Dot-Product Proofs
DESCRIPTION:Speaker: Prahladh  Harsha (TIFR)\n\nAbstract: \nA dot-product p
 roof is a simple probabilistic proof system in which the verifier decides 
 whether to accept an input vector based on a single linear combination of 
 the entries of the input and a proof vector. In this talk\, I will present
  constructions of linear-size dot-product proofs for circuit satisfiabilit
 y and discuss two kinds of applications: basing the exponential-time hardn
 ess of approximating MAX-LIN (maximal number of linear equations that can 
 be simultaneously satisfied) on the standard exponential-time hypothesis\,
  and minimizing the verification complexity of cryptographic proof systems
 .\n \n[Joint work with Nir Bitansky\, Yuval Ishai\, Ron Rothblum\, and Da
 vid Wu]\n
URL:https://www.tcs.tifr.res.in/web/events/1607
DTSTART;TZID=Asia/Kolkata:20250826T160000
DTEND;TZID=Asia/Kolkata:20250826T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1610
DTSTAMP:20250828T063457Z
SUMMARY:Language Generation in the Limit
DESCRIPTION:Speaker: Nishant Das (TIFR)\n\nAbstract: \nAlthough current lar
 ge language models are complex\, the most basic specifications of the unde
 rlying language generation problem are simple to state: given a finite set
  of training samples from an unknown language\, the task is to produce val
 id new strings from the language that do not already appear in the trainin
 g data. The question considered in this work is what can be concluded abou
 t language generation using only this specification\, without further assu
 mptions. In particular\, suppose that an adversary enumerates the strings 
 of an unknown target language L\, which is known only to come from a count
 ably infinite list of candidates. A computational agent is said to generat
 e from L in the limit if\, after some finite point in the enumeration\, it
  is able to produce new elements exclusively from L that have not yet bee
 n presented by the adversary. The main result established by the authors i
 s that there exists an agent that can generate in the limit for every coun
 table list of candidate languages. This stands in sharp contrast to the ne
 gative results of Gold and Angluin in the classical model of language lear
 ning by identification\, where the goal is to recover the exact target lan
 guage from samples. The difference between these two outcomes indicates th
 at identifying a language is a fundamentally different problem from genera
 ting from it.\nLink to the paper: https://proceedings.neurips.cc/paper_fi
 les/paper/2024/file/7988e9b3876ad689e921ce05d711442f-Paper-Conference.pdf\
 n
URL:https://www.tcs.tifr.res.in/web/events/1610
DTSTART;TZID=Asia/Kolkata:20250829T160000
DTEND;TZID=Asia/Kolkata:20250829T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1602
DTSTAMP:20250901T050447Z
SUMMARY:Commitments are equivalent to statistically-verifiable one-way stat
 e generators
DESCRIPTION:Speaker: Rahul Jain (National University of Singapore)\n\nAbstr
 act: \nOne-way state generators (OWSG) are natural quantum analogs to clas
 sical one-way functions. We consider statistically-verifiable OWSGs (sv-OW
 SG)\, which are potentially weaker objects than OWSGs. We show that O(n/lo
 g(n))-copy sv-OWSGs (n represents the input length) are equivalent to poly
 (n)-copy sv-OWSGs and to quantum commitments. Since known results show tha
 t o(n/log(n))-copy OWSGs cannot imply commitments (unless they exist uncon
 ditionally)\, this shows that O(n/log(n))-copy sv-OWSGs are the weakest OW
 SGs from which we can get commitments (and hence much of quantum cryptogra
 phy).\nOur construction follows along the lines of Hastad\, Impagliazzo\, 
 Levin\, and Luby [HILL 99]\, who obtained classical pseudorandom generator
 s (PRG) from classical one-way functions (OWF)\, however\, with crucial mo
 difications. Our construction\, when applied to the classical case\, provi
 des an alternative to the classical construction to obtain a classical mil
 dly non-uniform PRG from any classical OWF (from which a uniform PRG can b
 e obtained follwing along [HILL 99]). Since we do not argue conditioned on
  the output\, our construction and analysis are arguably simpler and may b
 e of independent interest.\nTalk based on: Commitments are equivalent to o
 ne-way state generators. Rishabh Batra\, Rahul Jain. FOCS\, 2024. QCrypt\,
  2024. TQC\, 2025.  ArXiv:2404.03220.\nShort Bio:Rahul Jain is a Professo
 r at the Computer Science Department\, National University of Singapore (N
 US). He was an Associate Professor from 2013 to 2019 and an Assistant Prof
 essor from 2009 to 2013 at NUS. He obtained his PhD from the Tata Institut
 e of Fundamental Research (TIFR)\, Mumbai\, India\, in 2003. He was a post
 -doctoral researcher at the University of California at Berkeley\, USA\, f
 rom 2004 to 2006 and at the Institute for Quantum Computing (IQC)\, Univer
 sity of Waterloo\, Canada\, from 2006 to 2008. He obtained a Bachelor's de
 gree (B.Tech) in Electrical and Electronics Engineering from the Indian In
 stitute of Technology\, Mumbai (IITB)\, India\, in 1997. He has been a Pri
 ncipal Investigator at the Centre for Quantum Technologies (CQT) in Singap
 ore since 2009.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1602
DTSTART;TZID=Asia/Kolkata:20250902T160000
DTEND;TZID=Asia/Kolkata:20250902T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1609
DTSTAMP:20250826T072015Z
SUMMARY:Fair and Efficient Allocation of Indivisible Mixed Manna
DESCRIPTION:Speaker: Aditi Sethia (IISc Bangalore)\n\nAbstract: \nIn this t
 alk\, we will discuss fair division of indivisible mixed manna (items whos
 e values may be positive\, negative\, or zero) among agents with additive 
 preferences. In such settings\, the existence of fair (approximate envy-fr
 ee) and efficient allocations is an intriguing open question even for thre
 e agents. We will see how fairness --- in terms of a new relaxation of env
 y-freeness --- and efficiency can always be achieved together. Specificall
 y\, our fairness guarantees are in terms of envy-freeness up to k realloca
 tions (EFR-k): An allocation A is said to be EFR-k if there exists a subse
 t R of at most k items such that\, for each agent i\, we can reassign item
 s from within R and obtain an allocation which is envy-free for i.Our resu
 lts advance the understanding of fair and efficient allocation of indivisi
 ble mixed manna and rely on a novel application of the Knaster-Kuratowski-
 Mazurkiewicz (KKM) Theorem in discrete fair division. We utilize weighted 
 welfare maximization\, with perturbed valuations\, to achieve Pareto effic
 iency\, and overall\, our techniques are notably different from existing m
 arket-based approaches.Short Bio: Aditi is currently a Post-Doctoral Fello
 w at the Indian Institute of Science\, Bangalore\, hosted by Prof. Siddhar
 th Barman. She received her PhD from IIT Gandhinagar\, advised by Prof. Ne
 eldhara Misra. Her research interests revolve around Computational Social 
 Choice (Fair Division\, Voting and Matching problems)\, Algorithmic Game T
 heory\, and Economics and Computation.\n
URL:https://www.tcs.tifr.res.in/web/events/1609
DTSTART;TZID=Asia/Kolkata:20250903T160000
DTEND;TZID=Asia/Kolkata:20250903T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1597
DTSTAMP:20250903T042832Z
SUMMARY:Giving Some Space Can Be Hard: Two New Models to Match Agents with 
 Locations
DESCRIPTION:Speaker: Shivika Narang (University of New South Wales)\n\nAbst
 ract: \nThere can be a multitude of reasons to match agents to specific lo
 cations in a given space. In this talk we cover two: distributing delivery
  orders and assigning shared hostel rooms. For both settings we shall try 
 to find solutions that satisfy desirable properties and characterize insta
 nces for which they exist. \n \nWe first initiate the study of fair dist
 ribution of delivery tasks among a set of agents wherein delivery jobs are
  placed along the vertices of a graph. Our goal is to fairly distribute de
 livery costs (modeled as a submodular function) among a fixed set of agent
 s while satisfying some desirable notions of economic efficiency. We chara
 cterize instances that admit fair and efficient solutions by exploiting un
 derlying graph structures. Unfortunately\, finding these solutions proves 
 to be NP-hard. We complement this by designing an XP algorithm (parameteri
 zed by the number of agents) that can find all fair and efficient solution
 s when they exist. We conclude this discussion by theoretically and experi
 mentally analyzing the price of fairness.\n \nWe shall then introduce Leo
 ntief utilities to the problem of roommate matchings. We aim to find strat
 egyproof mechanisms that give good bounds on agent welfare. We first find 
 that no approximation to welfare can be achieved under strategyproof mecha
 nisms for either Leontief or additive utilities. Even for binary additive 
 utilities no maximum welfare mechanism can be strategyproof. In contrast. 
 we then --surprisingly-- find that binary Leontief utilities enable us to 
 find strategyproof mechanisms that maximize welfare. Joint work with Hadi 
 Hosseini\, Sanjukta Roy and Tomasz Was.\nShort Bio:Shivika Narang is a pos
 tdoctoral fellow at UNSW Sydney. Previously she was a postdoc at Simons La
 ufer Mathematical Sciences Institute\, Berkeley (SLMath) and completed her
  PhD from IISc Bengaluru. During her PhD\, she received the Tata Consultan
 cy Services Research Fellowship. Her work is currently focused on finding 
 fair and efficient solutions to societal problems. She largely works in co
 mputational social choice\, especially matching and allocation problems.\n
URL:https://www.tcs.tifr.res.in/web/events/1597
DTSTART;TZID=Asia/Kolkata:20250909T160000
DTEND;TZID=Asia/Kolkata:20250909T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1617
DTSTAMP:20250910T083527Z
SUMMARY:Quantum Key Distribution: from qubits to qudits
DESCRIPTION:Speaker: Vikas Bhat (Dept. of Nuclear & Atomic Physics\, TIFR)\
 n\nAbstract: \nQuantum Key Distribution solves the major bottleneck of sym
 metric key cryptography\, the key distribution. As the name suggests\, it 
 uses laws of quantum mechanics to its advantage. I will discuss the mathem
 atics behind the simple qubit (quantum bit) version and extend it to qudit
 s (quantum d-bits). I will briefly touch upon how we realise such a system
  in our lab.\n
URL:https://www.tcs.tifr.res.in/web/events/1617
DTSTART;TZID=Asia/Kolkata:20250912T160000
DTEND;TZID=Asia/Kolkata:20250912T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1587
DTSTAMP:20250916T044349Z
SUMMARY:Oh the lonely runner!
DESCRIPTION:Speaker: Avinash Bhardwaj (IIT Bombay)\n\nAbstract: \nLonely Ru
 nner Conjecture\, proposed by Jörg M. Wills and so nomenclatured by Luis 
 Goddyn\, has been an object of interest since it was first conceived in 19
 67: Given positive integers k and n1\,n2\,...\,nk there exists a positive 
 real number t such that the distance of t·nj to the nearest integer is at
  least 1\\(k+1)\, ∀ 1 ≤ j ≤ k. The problem that originated in Diopha
 ntine approximation almost 6 decades ago\, is still widely open. Through t
 his talk I will attempt to share some interesting insights that have flown
  through academic circles over the long steady life of the problem\, along
  with some new key results.\nShort Bio:Avinash Bhardwaj is presently a fac
 ulty member in the Department of Industrial Engineering and Operations Res
 earch at IIT Bombay. His research interests broadly span mathematical opti
 mization with particular interests in discrete and combinatorial optimizat
 ion.\n
URL:https://www.tcs.tifr.res.in/web/events/1587
DTSTART;TZID=Asia/Kolkata:20250916T160000
DTEND;TZID=Asia/Kolkata:20250916T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1616
DTSTAMP:20250911T063920Z
SUMMARY:Learning to Control Unknown Multi-Agent Systems
DESCRIPTION:Speaker: Siddharth Chandak (Stanford University)\n\nAbstract: \
 nLarge-scale multi-agent systems are often modeled as games\, where each p
 layer's reward depends on the joint actions of all agents. In strongly mon
 otone games\, players converge to a Nash equilibrium (NE) by optimizing th
 eir local objectives\, but such equilibria may not align with the global o
 bjective. We study two scenarios where a game manager\, with access only t
 o the global objective and limited control over utility parameters\, seeks
  to steer the system toward better equilibria.\nIn the first scenario\, th
 e controller adjusts linear coefficients in the players' utilities to impo
 se linear constraints on the equilibrium. We design a simple two-time-scal
 e stochastic approximation algorithm and show almost sure convergence and 
 a mean square error rate of near-$O(t^{-1/4})$ for the algorithm.In the se
 cond scenario\, the game manager has to choose among K discrete parameters
 . We propose a novel optimism-based bandit algorithm with additional terms
  to account for the distance from equilibrium\, and prove that this algori
 thm achieves a regret of O(log(T)).\nShort Bio:Siddharth Chandak is curren
 tly a Ph.D. candidate in Electrical Engineering at Stanford University\, U
 SA. He received his B.Tech. from IIT Bombay\, India\, in 2021\, where he w
 as awarded the President of India Gold Medal\, and his M.S. from Stanford 
 University in 2023. His research interests include game theory\, multi-age
 nt learning\, stochastic approximation\, and its applications in reinforce
 ment learning.\n
URL:https://www.tcs.tifr.res.in/web/events/1616
DTSTART;TZID=Asia/Kolkata:20250917T160000
DTEND;TZID=Asia/Kolkata:20250917T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1619
DTSTAMP:20250918T060656Z
SUMMARY:Exponential Lower Bounds on the Size of ResLin Proofs of Nearly Qua
 dratic Depth
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \n\n
 Itsykson and Sokolov [IS14] identified resolution over parities\, denote
 d by ResLin\, as a natural and simple fragment of AC0​[2]-Frege for wh
 ich no super-polynomial lower bounds on size of proofs are known. Building
  on a recent line of work\, Efremenko and Itsykson [EI25] proved lower b
 ounds of the form exp​(NΩ​(1))\, on the size of ResLin proofs whos
 e depth is upper bounded by O​(N​log⁡N)\, where N is the number o
 f variables of the unsatisfiable CNF formula. The hard formula they used w
 as Tseitin on an appropriately expanding graph\, lifted by a 2-stifling g
 adget. They posed the natural problem of proving super-polynomial lower bo
 unds on the size of proofs that are Ω​(N1+ϵ) deep\, for any constant
  ϵ>0.\nWe provide a significant improvement by proving a lower bound on 
 size of the form exp​(Ω~​(Nϵ))\, as long as the depth of the ResLi
 n proofs are O​(N2−ϵ)\, for every ϵ>0. Our hard formula is again 
 Tseitin on an expander graph\, albeit lifted with a different type of gadg
 et. Our gadget needs to have small correlation with all parities.\nAn impo
 rtant ingredient in our work is to show that arbitrary distributions lift
 ed with such gadgets fool safe affine spaces\, an idea which originates
  in the earlier work of Bhattacharya\, Chattopadhyay and Dvorak [BCD24].\
 nThis talk is based on joint work with Arkadev Chattopadhyay.\n
URL:https://www.tcs.tifr.res.in/web/events/1619
DTSTART;TZID=Asia/Kolkata:20250919T160000
DTEND;TZID=Asia/Kolkata:20250919T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1624
DTSTAMP:20250926T051326Z
SUMMARY:The online primal-dual method
DESCRIPTION:Speaker: Arghya Chakraborty (TIFR)\n\nAbstract: \nThis talk wil
 l give a brief introduction to the online primal-dual method through the l
 ens of online bipartite matching. We will begin with the classic online bi
 partite matching problem and discuss two well-known algorithms: RANKING an
 d WATER-LEVEL. Using these as examples\, we will explore how a primal-dual
  perspective can be used to analyze their performance. The focus will be o
 n how the analysis can be carried out in an online fashion\, highlighting 
 a general approach that applies to a broad class of algorithms for online 
 bipartite matching.\n
URL:https://www.tcs.tifr.res.in/web/events/1624
DTSTART;TZID=Asia/Kolkata:20250926T160000
DTEND;TZID=Asia/Kolkata:20250926T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1626
DTSTAMP:20251001T044323Z
SUMMARY:Fair Randomized Allocations under Lexicographic Preferences
DESCRIPTION:Speaker: Surya Panchapakesan (IISER Pune)\n\nAbstract: \nA cent
 ral problem in fair division involves allocating a set of M indivisible 
 goods among N agents in a fair and efficient manner. The quintessenti
 al fairness notion is "envy freeness" (EF) where every agent prefers their
  own assignment over that of any other agent's. In the deterministic setti
 ng\, EF allocations may not always exist\, motivating the study of relaxat
 ions such as envy-freeness up to any good (EFX). While deciding the exi
 stence of EFX allocations remains unresolved even for just four agents wit
 h additive valuations\, interestingly\, Hosseini et al. showed that EF
 X allocations always exist and can be computed efficiently when agents hav
 e lexicographic preferences.\n \nTraditional approaches in the literatu
 re focus either on randomized allocations that are fair in expectation o
 r deterministic allocations that are "approximately" fair. Recently\, th
 ese two approaches have been reconciled in the form of "best-of-both-worl
 ds" guarantees [AFSV '24]\, wherein one seeks a randomized allocation tha
 t is fair in expectation (i.e.\, ex-ante fairness) while also being suppor
 ted on approximately fair allocations (i.e.\, ex-post fairness). \n \nIn
  this talk\, I will discuss some of our approaches at achieving best-of-bo
 th-worlds guarantees for agents with lexicographic preferences. I will fi
 rst introduce some of the techniques we use in our methods\, and then pres
 ent an algorithm that achieves ex-ante 6/7-EF and ex-post (EFX + PO). Foll
 owing this (if time permits)\, we shall see a refinement that strengthens 
 the ex-ante ratio to 9/10-EF while preserving the ex-post guarantees. \n
  \nThe talk is based on joint work with Telikepalli Kavitha\, Vignesh Vis
 wanathan\, Rohit Vaish and Jatin Yadav.\n
URL:https://www.tcs.tifr.res.in/web/events/1626
DTSTART;TZID=Asia/Kolkata:20251003T160000
DTEND;TZID=Asia/Kolkata:20251003T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1611
DTSTAMP:20250923T100142Z
SUMMARY:Instance-optimality in universal prediction
DESCRIPTION:Speaker: Alankrita Bhatt (Caltech)\n\nAbstract: \nData-driven d
 ecision-making systems seamlessly integrate into every facet of our daily 
 lives. Despite this ubiquity\, the current era has also brought with it a 
 host of emerging challenges such as the need to make good decisions in the
  presence of uncertainty (about the future and the environment) as well as
  the storage and processing of high-volume data to improve decision-making
 . In this talk\, I will discuss my research program\, which takes an infor
 mation-theoretic approach to modern problems arising in sequential decisio
 n-making. This perspective will be illustrated through the problem of un
 iversal prediction\, where the goal is to make accurate\, sequential forec
 asts without knowing in advance whether the data are stochastic\, adversar
 ial\, or somewhere in between. I will present new algorithms and fundament
 al limits that characterize what is and isn't possible in this setting\, h
 ighlighting broader principles for reliable decision-making under uncertai
 nty.\nShort Bio:Alankrita Bhatt is a Research Scientist at Granica Computi
 ng Inc\, in Mountain View\, CA. Prior to this she was a Center for the Mat
 hematics of Information postdoctoral fellow at Caltech and a research fell
 ow at the Simons Institute for the Theory of Computing\, UC Berkeley. She 
 received a Ph.D. in Electrical and Computer Engineering from UC San Diego\
 , and a B.Tech. in Electrical Engineering from the Indian Institute of Tec
 hnology Kanpur. Her research interests lie broadly at the intersection of 
 information theory\, statistics\, and data science\, with a recent focus o
 n sequential decision-making.\n
URL:https://www.tcs.tifr.res.in/web/events/1611
DTSTART;TZID=Asia/Kolkata:20251009T113000
DTEND;TZID=Asia/Kolkata:20251009T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1627
DTSTAMP:20251008T094225Z
SUMMARY:Convex Gaussian Min-Max Theorem for Precise Error Analysis of Regul
 arized Regression Problems in High Dimensions
DESCRIPTION:Speaker: Tirthankar Adhikari (TIFR)\n\nAbstract: \nConvex regul
 arized optimization methods such as the LASSO and Group-LASSO are central 
 to modern signal processing and high-dimensional regression problems. In t
 heir influential work\, Thrampoulidis\, Oymak\, and Hassibi introduced the
  Convex Gaussian Min-Max Theorem (CGMT)\, an elegant framework for preci
 se asymptotic error analysis of a wide class of convex regression problem
 s under Gaussian measurement models. Building on Gordon's Gaussian min-max
  theorem and ideas of Stojnic\, they showed that a complicated Primary Op
 timization (PO) problem can be replaced by a simpler\, analytically tract
 able Auxiliary Optimization (AO) problem whose solution precisely predict
 s key quantities such as the normalized squared error and optimal regulari
 zation parameters. Beyond its specific applications to linear and structur
 ed regression\, the CGMT provides a powerful conceptual bridge between hig
 h-dimensional probability and convex optimization\, enabling sharp asympto
 tic performance characterizations through the remarkably elegant PO to AO
  reduction.\n
URL:https://www.tcs.tifr.res.in/web/events/1627
DTSTART;TZID=Asia/Kolkata:20251010T160000
DTEND;TZID=Asia/Kolkata:20251010T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1615
DTSTAMP:20251001T063421Z
SUMMARY:Faster and Space Efficient Indexing for Locality Sensitive Hashing
DESCRIPTION:Speaker: Rameshwar Pratap (IIT Hyderabad)\n\nAbstract: \nThis w
 ork suggests faster and space-efficient index construction algorithms for 
 LSH for Euclidean distance (a.k.a. E2LSH) and cosine similarity (a.k.a. SR
 P). The index construction step of these algorithms relies on grouping dat
 a points into several bins of hash tables based on their hashcode. To gene
 rate an m-dimensional hashcode of the d-dimensional data point\, these LSH
 s first project the data point onto a d-dimensional random Gaussian vector
  and then discretise the resulting inner product. The time and space compl
 exity of both E2LSH and SRP for computing an m-sized hashcode of a d-dimen
 sional vector is O(md)\, which becomes impractical for large values of m a
 nd d. To overcome this problem\, we propose  LSH algorithms for both Eucl
 idean distance and cosine similarity that  reduce the hashcode computatio
 n time from O(md) to O(d)\, and simultaneously reduce the space complexity
  from O(md) to O(d). Our proposals are backed by mathematical guarantees\,
  and we validate their performance through numerical simulations on variou
 s real-world datasets.\nShort Bio:\nDr. Rameshwar Pratap is a faculty memb
 er at Department of CSE\, IIT Hyderabad. He earned his Ph.D. in Theoretica
 l Computer Science from Chennai Mathematical Institute (CMI). His research
  work lies in the intersection of theory and practice. Broadly his researc
 h work falls in the areas of "Algorithms for Massive Datasets"\, and focus
 es on developing  dimensionality reduction algorithms and sampling algori
 thms to handle the large dimensionality and volume of the datasets\, respe
 ctively. \n \n
URL:https://www.tcs.tifr.res.in/web/events/1615
DTSTART;TZID=Asia/Kolkata:20251014T160000
DTEND;TZID=Asia/Kolkata:20251014T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1630
DTSTAMP:20251017T064231Z
SUMMARY:Calibrated Language Models Must Hallucinate
DESCRIPTION:Speaker: Nishant Das (TIFR)\n\nAbstract: \nRecent language mode
 ls generate false but plausible-sounding text with surprising frequency. S
 uch “hallucinations” are an obstacle to the usability of language-base
 d AI systems and can harm people who rely upon their outputs. This work sh
 ows that there is an inherent statistical lower-bound on the rate that pre
 trained language models hallucinate certain types of facts\, having nothin
 g to do with the transformer LM architecture or data quality. For “arbit
 rary” facts whose veracity cannot be determined from the training data\,
  we show that hallucinations must occur at a certain rate for language mod
 els that satisfy a statistical calibration condition appropriate for gener
 ative language models. Specifically\, if the maximum probability of any fa
 ct is bounded\, we show that the probability of generating a hallucination
  is close to the fraction of facts that occur exactly once in the training
  data (a “Good-Turing” estimate)\, even assuming ideal training data w
 ithout errors. One conclusion is that models pretrained to be sufficiently
  good predictors (i.e.\, calibrated) may require post-training to mitigate
  hallucinations on the type of arbitrary facts that tend to appear once in
  the training set. However\, our analysis also suggests that there is no s
 tatistical reason that pretraining will lead to hallucination on facts tha
 t tend to appear more than once in the training data (like references to p
 ublications such as articles and books\, whose hallucinations have been pa
 rticularly notable and problematic) or on systematic facts (like arithmeti
 c calculations). Therefore\, different architectures and learning algorith
 ms may mitigate these latter types of hallucinations\n
URL:https://www.tcs.tifr.res.in/web/events/1630
DTSTART;TZID=Asia/Kolkata:20251017T160000
DTEND;TZID=Asia/Kolkata:20251017T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1628
DTSTAMP:20251014T090649Z
SUMMARY:Generalization Bounds for Dependent Data using Online-to-Batch Conv
 ersion
DESCRIPTION:Speaker: Sagnik Chatterjee (IIIT Delhi)\n\nAbstract: \n\nIn thi
 s work\, we upper bound the generalization error of batch learning algorit
 hms trained on samples drawn from a mixing stochastic process (i.e.\, a de
 pendent data source) both in expectation and with high probability. Unlike
  previous results by Mohri et al. (JMLR 2010) and Fu et al. (ICLR 2023)\, 
 our work does not require any additional stability assumptions on the batc
 h learner itself. This is made possible due to our use of the Online-to-Ba
 tch ( OTB ) conversion framework\, which allows us to shift the burden of 
 stability from the batch learner to an artificially constructed online lea
 rner. We prove that our bounds are equal to the bounds in the i.i.d. setti
 ng (i.e.\, optimal) up to a term that depends on the decay rate of the und
 erlying mixing stochastic process. Central to our analysis is a new notion
  of algorithmic stability for online learning algorithms based on Wasserst
 ein distances of order one. Furthermore\, we prove that the EWA algorithm\
 , a textbook family of online learning algorithms\, satisfies our new noti
 on of stability.\nShort Bio:Sagnik Chatterjee recently obtained his Ph.D. 
 from IIIT Delhi\, where he was advised by Dr. Debajyoti Bera. Prior to his
  Ph.D.\, Sagnik was a software engineer at Oracle in Bangalore. Sagnik's m
 ain research interest is in Quantum Computing with a particular focus on L
 earning Theory and Shallow Circuit Complexity. \n
URL:https://www.tcs.tifr.res.in/web/events/1628
DTSTART;TZID=Asia/Kolkata:20251021T160000
DTEND;TZID=Asia/Kolkata:20251021T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1631
DTSTAMP:20251024T044341Z
SUMMARY:Homomorphic Secret Sharing Constructions
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \n\nSuppose two 
 parties\, at most one of them being semi-honest\, attempt to compute a fun
 ction interactively and securely. The communication incurred during such a
  computation\, while done unconditionally\, depends on the circuit-size of
  the function being computed. However\, it is possible to break this 'circ
 uit-size barrier' if we have the LWE (learning with errors) assumption\, s
 ince we know how to get fully homomorphic encryption (FHE) from LWE and th
 en using FHE with this simple protocol - the first party encrypts its inpu
 t and sends them to the second party and then the second party applies the
  function locally under the FHE and outputs the function value. \nIn a 20
 16 CRYPTO paper\, Boyle\, Gilboa and Ishai constructed a primitive known a
 s Homomorphic Secret Sharing\, which also breaks the circuit-size barrier 
 for certain circuits\, but without heavy assumptions like LWE. In fact the
  only assumption they used was DDH (decisional Diffie-Hellman). In this ta
 lk\, we will see this construction.\npaper link - https://eprint.iacr.org/
 2016/585.pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1631
DTSTART;TZID=Asia/Kolkata:20251024T160000
DTEND;TZID=Asia/Kolkata:20251024T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1625
DTSTAMP:20251028T062631Z
SUMMARY:A Model predictive control approach for asymptotic optimality of Re
 stless Multi-armed Bandits
DESCRIPTION:Speaker: Dheeraj Narasimha (University of Grenoble\, France)\n\
 nAbstract: \nThe classical restless multi-armed bandit problem comprises o
 f $N$ bandit arms (slot machines) each with an associated state. A player 
 chooses a collection of at most $\\alpha N $ arms to play\, the remaining 
 arms are left untouched. At the next instance each arm evolves to a new st
 ate according to a stochastic transition process leaving the player with a
  reward depending on the player's action. Concretely\, the arms provide a 
 reward that is dependent on both the state and action of the arm at each t
 ime instance. This reward process is repeated over an infinite time horizo
 n. The player wishes to maximize the average reward obtained from this pro
 cess. Restless Multi-armed Bandits are known to be PSPACE hard combinatori
 al problems. Such problems find applications in a number of different fiel
 ds including wireless communication\, clinical trial design and web-crawl
 ing.This problem was first proposed by Whittle in 1988\, he conjectured t
 hat a priority order based on what is called the Whittle's index will prov
 ide an asymptotically optimal solution to this problem under a condition 
 called \\emph{indexability}. Unfortunately\, we now know of counter-examp
 les where this is not true. In this talk I will introduce a relaxation to
  the RMAB problem with a corresponding extension to the Whittle index pol
 icy that provably gives us asymptotically optimal solutions under easy to
  verify conditions.\nShort Bio:Dheeraj Narasimha obtained his PhD degree f
 rom Arizona State University under Prof. Lei Ying in 2021 while working on
  mean-field ames for density dependent continuous time markov processes. H
 e then went on to do a post-doctoral fellowship under Prof. Srinivas Shakk
 ottai at Texas A & M University and then completed a second post-doc at I
 NRIA\, CNRS under Dr. Nicolas Gast where he worked on restless multi-arme
 d bandits . His work on mean-field games has won runner-up best-paper priz
 es in ACM mobihoc as well as most recently in IEEE INFOCOM.The main focus
  of his work revolves around solving decision problems with many particip
 ants under weak interaction\, be it through weak graph limits\, potential
  games or mean field structures.\n
URL:https://www.tcs.tifr.res.in/web/events/1625
DTSTART;TZID=Asia/Kolkata:20251028T160000
DTEND;TZID=Asia/Kolkata:20251028T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1621
DTSTAMP:20251029T044421Z
SUMMARY:Singularity Testing: From the Non-Commutative to the Commutative Wo
 rld
DESCRIPTION:Speaker: Abhranil Chatterjee (IIT Kanpur)\n\nAbstract: \nDerand
 omizing the Polynomial Identity Testing (PIT) remains one of the central o
 pen problems in theoretical computer science. An (almost) equivalent formu
 lation of this problem is the singularity testing\, which asks whether a g
 iven symbolic matrix is invertible. While derandomization in the commutati
 ve setting continues to be elusive\, the non-commutative version of the pr
 oblem admits deterministic polynomial-time algorithms [Garg–Gurvits–Ol
 iveira–Wigderson (FOCS\, 2016)\, Ivanyos–Qiao–Subrahmanyam (ITCS\, 2
 017)].\nIn this talk\, I will describe an intermediate model that generali
 zes both the commutative and non-commutative settings\, and present a dete
 rministic polynomial-time algorithm for singularity testing even when some
  of the variables are allowed to commute. I will conclude by highlighting 
 several consequences and applications of this result.\nThis talk is based 
 on joint work with V. Arvind and Partha Mukhopadhyay.\nShort Bio:I am an a
 ssistant professor in the Department of Computer Science and Engineering a
 t IIT Kanpur\, since December 2024. Before joining IIT Kanpur\, I was an I
 NSPIRE Faculty at the Indian Statistical Institute\, Kolkata\, a visiting 
 faculty member at NISER Bhubaneswar\, and a Postdoctoral Researcher at IIT
  Bombay. I earned my PhD in 2022 from The Institute of Mathematical Scienc
 es\, Chennai\, under the supervision of Professors V. Arvind and Partha Mu
 khopadhyay. My research interest lies on the theoretical foundations of co
 mputer science\, with a focus on algebraic complexity theory and the desig
 n of algebraic algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1621
DTSTART;TZID=Asia/Kolkata:20251029T113000
DTEND;TZID=Asia/Kolkata:20251029T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1633
DTSTAMP:20251030T052235Z
SUMMARY:Leakage-Resilient Circuits against NC1
DESCRIPTION:Speaker: Ratnakar Medepalli (TIFR)\n\nAbstract: \nMost security
  games in cryptography assume the adversary has only black-box access to t
 he primitives. This leads to constructions that are secure in theory when 
 the adversary is restricted to such access\, but potentially vulnerable to
  side-channel attacks when implemented in practice. Leakage-resilient circ
 uits are circuit compilers that produce circuits that remain secure even w
 hen some 'side-channel' information about the internal computation is leak
 ed. In this talk\, we will see the constructions of LRCs against leakage f
 unctions in NC1\, from the paper Leakage-Resilient Circuits against NC1\,
  Revisited by Yuyu Wang.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1633
DTSTART;TZID=Asia/Kolkata:20251031T160000
DTEND;TZID=Asia/Kolkata:20251031T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1613
DTSTAMP:20251030T103822Z
SUMMARY:Incentives and Information in Algorithmics Economics
DESCRIPTION:Speaker: Divyarthi Mohan (Boston University)\n\nAbstract: \nDig
 ital markets and platforms have shaped the algorithmic landscape into a co
 mplex ecosystem of strategic\, self-interested entities. This has motivate
 d the study and development of mechanisms or algorithms that are robust to
  strategic behaviour\, using tools from algorithms\, game theory and econo
 mics. Standard assumptions in mechanism design are too strong to capture t
 he informational challenges present in many real scenarios\, from ad aucti
 ons where bidders' values depend on competitors' private market data\, to 
 resource allocation where there is uncertainty about future demands. In th
 is talk\, I will provide an overview of my recent work that tackles three 
 important challenges—strategic behavior\, interdependence\, and online d
 ecision making—going beyond standard assumptions. In particular\, I will
  focus on my work establishing the first constant-approximation algorithms
  for prophet and secretary problems with interdependent values.\nShort Bio
 :Divyarthi Mohan is a postdoctoral researcher in the Faculty of Computing 
 & Data Sciences at Boston University\, hosted by Kira Goldner. Her researc
 h broadly lies at the intersection of computer science and economics\, wit
 h a focus on algorithmic mechanisms design and the interplay of incentives
  and information. She obtained her PhD in Computer Science at Princeton Un
 iversity\, advised by Matt Weinberg\, and was previously a postdoctoral fe
 llow at Tel Aviv University hosted by Michal Feldman. Her research has bee
 n recognized with the Simons-Berkeley Research Fellowship for Fall 2022\, 
 the class of 2021 Siebel Scholarship\, and 2019 SEAS award for excellence 
 at Princeton University\, and her work was invited to the Highlights Beyon
 d EC 2024.\n
URL:https://www.tcs.tifr.res.in/web/events/1613
DTSTART;TZID=Asia/Kolkata:20251103T113000
DTEND;TZID=Asia/Kolkata:20251103T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1634
DTSTAMP:20251106T044359Z
SUMMARY:User-level Locally Differentially Private Gaussian Mean Estimation
DESCRIPTION:Speaker: Malhar Ajit  Managoli (TIFR)\n\nAbstract: \nDifferenti
 al Privacy addresses the problem of releasing aggregate statistics of some
  dataset (e.g. mean) while preserving the privacy of users who contributed
  the data (usually involving adding noise). DP is used for example when re
 leasing census data. There might be situations where the users do not trus
 t the authority collecting the data. For such cases\, Locally Differential
 ly Private protocols have been developed\, wherein users only ever send no
 isy versions of their data to the central server\, instead of the server c
 ollecting the data\, processing it\, and then adding noise. In this talk\,
  I will present a protocol for estimating the mean of a Gaussian variable 
 in an LDP manner. Based on "Distributed Private Mean Estimation" by Girgis
 \, Data\, and Diggavi.\n
URL:https://www.tcs.tifr.res.in/web/events/1634
DTSTART;TZID=Asia/Kolkata:20251107T160000
DTEND;TZID=Asia/Kolkata:20251107T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1612
DTSTAMP:20251029T091639Z
SUMMARY:Inductive Functional Proofs for Trustworthy Autonomy
DESCRIPTION:Speaker: Vishnu Murali (University of Colorado\, Boulder)\n\nAb
 stract: \nThe advent of autonomous systems in mission-critical areas such 
 as autonomous vehicles and medical devices has led to significant research
  in ensuring their correctness. A prominent approach to provide such guara
 ntees is to use functions that act as inductive proofs. To automate the se
 arch for such functions\, one typically fixes their template (e.g. polynom
 ials of a fixed degree). The search for these functions can then be handle
 d using optimization-based approaches to find suitable candidates within t
 he template class. When one fails to find such a function\, a common appro
 ach is to change the template (for example increase the degree of the poly
 nomial) and try again. An alternative approach is to instead change what w
 e induct over. In this talk\, I will illustrate how different notions of i
 nduction can be used to provide guarantees for specifications that range f
 rom safety to privacy. Finally\, I will discuss two directions for future 
 work: first to ensure the accountability for such systems and second\, to 
 find automated approaches to search for other novel inductive proof rules.
 \nShort Bio:Vishnu Murali is a postdoctoral associate in the Department of
  Computer Science at the University of Colorado Boulder. He received his P
 hD degree from the University of Colorado Boulder\, USA in 2024. The focus
  of his research is to provide guarantees for autonomous or cyber-physical
  systems against properties specified in logic or via automata. During his
  PhD\, he received awards for his research from the department of Computer
  Science at the University of Colorado Boulder\, and one of his papers was
  a finalist for the ACM SIGBED HSCC best paper award.\n
URL:https://www.tcs.tifr.res.in/web/events/1612
DTSTART;TZID=Asia/Kolkata:20251111T160000
DTEND;TZID=Asia/Kolkata:20251111T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1638
DTSTAMP:20251112T173923Z
SUMMARY:Factors of Constant-Depth Circuits: Deterministic Algorithms and St
 ructural Bounds
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nMultivariate po
 lynomial factorization is a fundamental algebraic problem with connections
  to error-correcting codes\, pseudorandomness and complexity theory. Const
 ant-depth circuits form a restricted yet natural subclass of general polyn
 omial-size arithmetic circuits\, capturing a wide variety of algebraic pro
 blems. In this talk\, we will try and understand some of the ideas that we
 nt into a recent line of work that concluded with a deterministic factoriz
 ation algorithm for constant-depth circuits. More generally\, we will see 
 that for most natural algebraic models\, deterministic (black-box) polynom
 ial identity testing is sufficient for deterministic factorization.At the 
 heart of these algorithmic results\, we will use polynomial identity testi
 ng to project multivariate polynomials to univariate polynomials while pre
 serving information about the factors. The final algorithmic result in thi
 s line of work builds upon a recent surprising and important structural re
 sult: constant-depth circuits (and most natural algebraic models) are clos
 ed under factoring -- if a polynomial has a constant-depth circuit\, then 
 so do its factors.  This talk will be based on collaborations with Somnat
 h Bhattacharjee\, Mrinal Kumar\, Shanthanu Suresh Rai\, Ramprasad Sapthari
 shi\, Shubhangi Saraf and Ben Lee Volk.\n
URL:https://www.tcs.tifr.res.in/web/events/1638
DTSTART;TZID=Asia/Kolkata:20251113T173000
DTEND;TZID=Asia/Kolkata:20251113T183000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1639
DTSTAMP:20251113T055807Z
SUMMARY:Identification of Joint Interventional Distributions in Recursive S
 emi-Markovian Causal Model
DESCRIPTION:Speaker: Spandan Poddar (TIFR)\n\nAbstract: \nThis paper is con
 cerned with estimating the effects of actions from causal assumptions\, r
 epresented concisely as a directed graph\, and statistical knowledge\, gi
 ven as a probability distribution. In this talk\, I will present the ID a
 lgorithm\, talk about  necessary and sufficient graphical conditions for 
 the cases when the causal effect of an arbitrary set of variables on anoth
 er arbitrary set can be determined uniquely from the available information
 .\nLink to the paper:https://cdn.aaai.org/AAAI/2006/AAAI06-191.pdf\n \n
URL:https://www.tcs.tifr.res.in/web/events/1639
DTSTART;TZID=Asia/Kolkata:20251114T160000
DTEND;TZID=Asia/Kolkata:20251114T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1614
DTSTAMP:20251110T065745Z
SUMMARY:Analytic Insights into the Zig-Zag Product and Its Friends
DESCRIPTION:Speaker: Gil Cohen (Tel Aviv University)\n\nAbstract: \nThe wel
 l-known Zig-Zag product and related graph operators\, like derandomized sq
 uaring\, are fundamentally combinatorial in nature. Classical bounds on th
 eir behavior often rely on a mix of combinatorics and linear algebra. Howe
 ver\, these traditional bounds are not tight.\nIn this talk\, we will pres
 ent a more refined analysis that utilizes the full spectrum of the graph\,
  rather than relying solely on its spectral expansion. This approach produ
 ces results that both match experimental observations and\, in a sense\, a
 re proved to be optimal. Our technique is analytic\, diverging from classi
 cal methods: for the upper bound\, we apply finite free probability\, whil
 e for the lower bound\, we draw on results from analytic combinatorics.\nB
 ased on joint works with Itay Cohen\, Gal Maor and Yuval Peled.\nNo prior 
 knowledge is required.\nShort Bio:Gil Cohen has been a professor in the De
 partment of Computer Science at Tel Aviv University since 2018. Previously
 \, he was a postdoctoral researcher at Caltech and Princeton University\, 
 after graduating from the Weizmann Institute of Science\, where he was adv
 ised by Ran Raz. His research focuses on pseudorandomness and derandomizat
 ion\, explicit constructions\, coding theory (especially algebraic geometr
 y codes\, tree codes\, and locally decodable codes)\, and spectral graph t
 heory\, often through the lens of free probability theory.\n
URL:https://www.tcs.tifr.res.in/web/events/1614
DTSTART;TZID=Asia/Kolkata:20251118T143000
DTEND;TZID=Asia/Kolkata:20251118T153000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1641
DTSTAMP:20251120T093528Z
SUMMARY:Sparse Mean Estimation in Adversarial Settings via Incremental Lear
 ning
DESCRIPTION:Speaker: Santanu Das (TIFR)\n\nAbstract: \nSparse mean estimati
 on is a fundamental problem in high-dimensional statistics\, arising in di
 verse applications such as signal processing\, genomics\, and machine lear
 ning. However\, real-world datasets are rarely clean—samples are often c
 orrupted by adversarial noise or malicious outliers. This motivates the st
 udy of robust sparse mean estimation\, where the goal is to design estimat
 ors that remain accurate even when a fraction of the data has been arbitra
 rily contaminated.\nIn this talk\, we discuss the recent paper “Sparse M
 ean Estimation in Adversarial Settings via Incremental Learning”\, which
  provides a new perspective on achieving robustness through Hadamard param
 eterization. While Hadamard parameterization has proven useful in classica
 l sparse estimation tasks\, this paper demonstrates how it can be leverage
 d to obtain a provably robust sparse mean estimation algorithm. The method
  combines the structural benefits of Hadamard parameterisation with previo
 usly known robust estimation techniques. The resulting estimator achieves 
 strong performance guarantees in adversarial settings while maintaining co
 mputational efficiency.\n
URL:https://www.tcs.tifr.res.in/web/events/1641
DTSTART;TZID=Asia/Kolkata:20251121T160000
DTEND;TZID=Asia/Kolkata:20251121T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1618
DTSTAMP:20251114T073031Z
SUMMARY:Boolean Observation Games
DESCRIPTION:Speaker: Sunil Simon (IIT Kanpur)\n\nAbstract: \nGame theoretic
  models have proved to be quite versatile in the analysis of multi-agent s
 ystems. Solution concepts like equilibria provide a description of the pos
 sible outcomes. From the perspective of computer science\, one of the fund
 amental questions is the complexity of computing equilibria in such game m
 odels\, which in turn require the representation of the model to be compac
 t. While explicit descriptions of classical game theoretic models don't fi
 t this criterion\, there are various approaches based on constraining the 
 quantitative payoff functions to achieve compact representation. These res
 ult in various well-studied classes of games like polymatix games and addi
 tively separable hedonic games. Another approach is to use a logical langu
 age to represent agents' objectives.In this talk\, we propose a qualitativ
 e model for incomplete information games that has a compact representation
 . We identify structural properties which guarantee the existence of equil
 ibria. We identify the fragment which precisely corresponds to ``Boolean g
 ames'' (a well-studied model of strategic games with Boolean objectives). 
 We also provide complexity results for the natural questions of verificati
 on and checking of the emptiness of equilibrium outcomes in this class of 
 games.This is joint work with Hans van Ditmarsch (CNRS\, IRIT France).Shor
 t Bio:Sunil Simon received his PhD from the Institute of Mathematical Scie
 nce\, Chennai and is currently a faculty member at the Department of Compu
 ter Science and Engineering\, IIT Kanpur. His research interests include f
 ormal verification\, logical foundations of multiple-agent systems and com
 putational analysis of games.\n
URL:https://www.tcs.tifr.res.in/web/events/1618
DTSTART;TZID=Asia/Kolkata:20251125T100000
DTEND;TZID=Asia/Kolkata:20251125T110000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1637
DTSTAMP:20251125T072134Z
SUMMARY:Almost Tight Additive Guarantees for k-Edge-Connectivity
DESCRIPTION:Speaker: Nikhil Kumar (TIFR)\n\nAbstract: \nWe study the k-edge
 -connected spanning subgraph (k-ECSS) problem: given an undirected graph G
  with nonnegative edge costs\, the objective is to find a minimum-cost k-e
 dge-connected spanning subgraph. For even k\, we present a polynomial-time
  algorithm that constructs a k-edge-connected subgraph whose cost is at mo
 st the optimal value of the natural LP relaxation for k-ECSS. Since k-ECSS
  is NP-hard for all k ≥ 2\, these guarantees are nearly optimal. Moreove
 r\, our results substantially improve upon the recent work of Hershkowitz\
 , Klein\, and Zenklusen\, both in approximation quality and the simplicity
  of the algorithm and its analysis.\n
URL:https://www.tcs.tifr.res.in/web/events/1637
DTSTART;TZID=Asia/Kolkata:20251126T160000
DTEND;TZID=Asia/Kolkata:20251126T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1643
DTSTAMP:20251126T054942Z
SUMMARY:Catalytic Computing: A Primer
DESCRIPTION:Speaker: Ian Mertz (Charles University)\n\nAbstract: \nCan memo
 ry be useful even when it's already full? In the catalytic computing mode
 l (Buhrman et al. 2014)\, we consider a space bounded Turing machine with 
 additional access to a much larger hard drive\, with the caveat that the i
 nitial contents of this extra space must be restored after any computation
 . Despite this restriction\, catalytic computation gains surprising power
  over ordinary space-bounded computation\, even above and beyond resources
  such as randomness and non-determinism.In this talk we will survey the fi
 eld of catalytic computation. We will cover the base catalytic model and w
 here it fits into traditional complexity theory\; variants of the model\, 
 such as lossy\, randomized\, non-deterministic\, and non-uniform catalytic
  computation\; known techniques\, such as register programs and compress-o
 r-random approaches\; applications of catalytic ideas to other settings\; 
 and potential directions for the future of the field.\nShort Bio:Ian Mertz
  is a postdoctoral researcher at the Computer Science Institute (IUUK) at 
 Charles University in Prague. His work revolves around catalytic computing
 \, a branch of space-bounded algorithms dealing with the use of full memor
 y as a computational resource\, as well as the study of how the complexity
  of problems compose over many instances. He received a B.Sc./B.A. from Ru
 tgers University in 2016\, an M.Sc. from University of Toronto in 2018\, a
 nd a Ph.D. in computer science from University of Toronto in 2022\, and ha
 s since held positions at University of Warwick and Charles University.\n
URL:https://www.tcs.tifr.res.in/web/events/1643
DTSTART;TZID=Asia/Kolkata:20251128T113000
DTEND;TZID=Asia/Kolkata:20251128T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1646
DTSTAMP:20251127T052546Z
SUMMARY:Stability Notions for Hospital Residents with sizes
DESCRIPTION:Speaker: Krishnashree J B (TIFR)\n\nAbstract: \nThe Hospital/Re
 sidents (HR) problem is an extensively studied many-one matching with pref
 erences problem. It is known for its application in the National Resident 
 Matching Program\, which allocates medical interns (or residents) to hospi
 tals. The celebrated Gale–Shapley algorithm guarantees that a stable mat
 ching always exists and can be efficiently computed. We study the Hospita
 l/Residents problem with Sizes (HRS)\, a generalisation where each agent a
  is a group of residents of size s(a). Feasibility and stability of the ma
 tching are defined accordingly. Unlike the classical HR problem\, an insta
 nce of HRS may not admit a stable matching. It is known that deciding whet
 her an instance admits a stable matching is NP-hard. In this talk\, we pr
 ovide an efficient algorithm for computing a stable matching in all instan
 ces of a restricted version of HRS. In this talk\, we discuss a variation 
 of the classical stability notion called occupancy-stable and a polynomial
 -time algorithm to compute the same. Moreover\, computing a maximum-size o
 ccupancy-stable matching is NP-hard. We complement our hardness result by 
 providing an approximation algorithm.\nhttps://arxiv.org/abs/2506.03638\n
URL:https://www.tcs.tifr.res.in/web/events/1646
DTSTART;TZID=Asia/Kolkata:20251128T160000
DTEND;TZID=Asia/Kolkata:20251128T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1600
DTSTAMP:20251202T084920Z
SUMMARY:Contextual Generalized Linear Bandits
DESCRIPTION:Speaker: Gaurav Sinha (Microsoft)\n\nAbstract: \nIn this talk\,
  I will present algorithms for the contextual bandit problem with generali
 zed linear rewards. Motivated by practical situations\, I will discuss bat
 ched versions of the problem and develop algorithms that can scale to very
  large action sets while attaining optimal regret with respect to the numb
 er of rounds and the non-linearity of the reward model. Our techniques inc
 lude appropriate optimal designs constructions combined with linear optimi
 zation oracles and action scaling to account for reward nonlinearity. I wi
 ll sketch our proof idea for some of the main results and also present emp
 irical results if time permits.\nShort Bio:I am a Principal Researcher at 
 Microsoft Research\, working in the areas of Reinforcement Learning\, Caus
 al Inference and Learning Theory. I received my Ph.D. in Mathematics from
  the California Institute of Technology in 2016\, where I was advised by P
 rof. Eric Rains and my Integrated M.Sc. in Mathematics and Scientific Comp
 uting from Indian Institute of Technology (IIT) Kanpur in 2011. My primary
  research interest lies in sequential decision-making\, particularly as ap
 plied to real world applications such as online advertising and recommenda
 tion systems. I focus on scenarios where decision-makers have access to bo
 th observational and interventional data. While observational data is abun
 dant and inexpensive\, interventional data\, though costly\, provides more
  granular insights into the impact of specific decisions. My research aims
  to develop algorithms that optimally balance the use of these data types\
 , ensuring both theoretically sound and practically viable decision-making
  over extended periods. To achieve this\, I employ a diverse toolkit encom
 passing causal inference\, nonlinear and stochastic optimization\, optimal
  experimental design etc.\n
URL:https://www.tcs.tifr.res.in/web/events/1600
DTSTART;TZID=Asia/Kolkata:20251202T160000
DTEND;TZID=Asia/Kolkata:20251202T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1649
DTSTAMP:20251201T085026Z
SUMMARY:Computing with a full hard drive.
DESCRIPTION:Speaker: Ian Mertz (Charles University)\n\nAbstract: \nSpace an
 d time are the two most foundational resources in the study of computation
 . However\, they behave in very different ways that can make our intuition
 s fail. One key difference is that space\, once it has been used for one p
 urpose\, can be erased and reused for another\, while time spent is gone f
 orever. Just ten years ago\, Buhrman et al. discovered a shocking fact: ev
 en memory which is completely full can be reused\, without erasure\, for u
 nrelated purposes. Inspired by chemistry\, they defined catalytic space as
  memory which aids a computation without being altered by the process. \n
 In this talk\, we introduce the field of catalytic computation\, from its 
 inception to the recent explosion of results in the past few years. We wil
 l give an overview of the major techniques for using full memory as well a
 s its greatest successes\, including a novel relationship between space an
 d time. Finally\, we reflect on how re-using full memory forces us to reco
 nsider our understanding of space.\nShort Bio:Ian Mertz is a postdoctoral 
 researcher at the Computer Science Institute (IUUK) at Charles University 
 in Prague. His work revolves around catalytic computing\, a branch of spac
 e-bounded algorithms dealing with the use of full memory as a computationa
 l resource\, as well as the study of how the complexity of problems compos
 e over many instances. He received a B.Sc./B.A. from Rutgers University in
  2016\, an M.Sc. from University of Toronto in 2018\, and a Ph.D. in compu
 ter science from University of Toronto in 2022\, and has since held positi
 ons at University of Warwick and Charles University\n
URL:https://www.tcs.tifr.res.in/web/events/1649
DTSTART;TZID=Asia/Kolkata:20251203T160000
DTEND;TZID=Asia/Kolkata:20251203T170000
LOCATION:Main Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1635
DTSTAMP:20251119T062441Z
SUMMARY:Approximation Algorithms for Optimization under Uncertainty
DESCRIPTION:Speaker: Sharat Ibrahimpur (ETH Zurich)\n\nAbstract: \nUncertai
 nty is ubiquitous in real-world problems\, highlighting a growing need for
  new mathematical and algorithmic tools for optimization under uncertainty
 . In this talk\, I will discuss two prominent hurdles that arise in stocha
 stic combinatorial optimization\, along with recent advances that address 
 these challenges. \nThe first setting considers a generic combinatorial o
 ptimization problem in which the costs are random variables with known dis
 tributions\, and feasible solutions induce multi-dimensional cost vectors.
  The algorithmic goal is to compute an oblivious solution that minimizes t
 he expected norm of the associated cost vector for a given monotone\, symm
 etric norm. One can show that optimizing the norm of the expected cost vec
 tor may yield solutions whose approximation quality degrades with the dime
 nsionality of the problem. I will present a powerful theorem\, dubbed appr
 oximate stochastic majorization\, that enables constant-factor approximati
 ons for norm-based objectives across a wide class of combinatorial optimiz
 ation problems. \nI will then turn to stochastic decision environments wh
 ere forgoing adaptivity for simplicity or analytical convenience can lead 
 to poor approximation guarantees. I will illustrate this through a novel v
 ariant of two-stage stochastic load balancing that enables a quantitative 
 trade-off between the practical benefits of non-adaptive algorithms and th
 eir performance limitations. I will present a striking power-of-two-choice
 s result for stochastic load balancing\, showing that constant-factor appr
 oximations are achievable with limited adaptivity relative to the omniscie
 nt and adaptive optimums. \nShort Bio:Sharat Ibrahimpur is a postdoctoral
  researcher in the Computer Science department at ETH Zurich. Previously\,
  he held postdoctoral positions at the University of Bonn and the London S
 chool of Economics. Sharat earned his M.Math. and Ph.D. degrees in Combina
 torics and Optimization from the University of Waterloo. He completed his 
 undergraduate degree in Applied Mathematics at the Indian Institute of Tec
 hnology Roorkee. Sharat's research focuses on designing approximation algo
 rithms for combinatorial optimization problems\, with a special emphasis o
 n optimization under uncertainty. \n
URL:https://www.tcs.tifr.res.in/web/events/1635
DTSTART;TZID=Asia/Kolkata:20251204T113000
DTEND;TZID=Asia/Kolkata:20251204T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1652
DTSTAMP:20251204T101911Z
SUMMARY:Finding equilibria: easier for optimists\, easiest for pessimists
DESCRIPTION:Speaker: Léonard Brice (Université libre de Bruxelles and IST
  Austria)\n\nAbstract: \n\nIn multiplayer games played on graphs\, as soon
  as randomness is involved (because the game is stochastic or because the 
 players are allowed to randomise their strategies)\, deciding the existenc
 e of a Nash equilibrium that satisfies a given constraint\, for example su
 ch that the players' payoffs lie in specified intervals\, is undecidable i
 n all reasonable settings. However\, these results rely on a definition of
  Nash equilibria that implies that each player intends to maximise their e
 xpected payoff\, which is not always the most rational behaviour: their to
 lerance to risk may vary. In this talk\, we consider the pessimistic risk 
 measure\, which interprets randomness by considering the worst possible sc
 enario\, and its dual\, the optimistic risk measure. We define from those 
 notions a new notion of equilibrium\, the extreme risk-sensitive equilibri
 um\, and show that the constrained existence problem of such an equilibriu
 m is decidable.\nShort Bio:Léonard Brice recently completed a PhD in theo
 retical computer science in the Free university of Brussels\, and is now s
 tarting a post-doc at the Institute of Science and Technology Austria\, wi
 th Thomas Henzinger. His research focuses on multiplayer games\, in partic
 ular games played on graphs\, toward applications to multi-agent systems.\
 n
URL:https://www.tcs.tifr.res.in/web/events/1652
DTSTART;TZID=Asia/Kolkata:20251205T110000
DTEND;TZID=Asia/Kolkata:20251205T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1651
DTSTAMP:20251204T093934Z
SUMMARY:Local to global phenomenon for average-radius list decoding
DESCRIPTION:Speaker: Soumyadeep Paul (TIFR)\n\nAbstract: \nThe distance amp
 lification procedure of Alon\, Edmonds\, Luby showed how to transform any 
 high rate code into one with near-optimal rate-distance tradeoff\, which i
 s essentially a local to global phenomenon for the distance of a code. We 
 will see a similar local to global phenomenon for average-radius list deco
 ding for the AEL procedure. This would give us codes which approach the ge
 neralized Singleton bound.\nBased on https://arxiv.org/pdf/2502.07308 by J
 eronimo\, Mittal\, Srivastava\, Tulsiani.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1651
DTSTART;TZID=Asia/Kolkata:20251205T160000
DTEND;TZID=Asia/Kolkata:20251205T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1647
DTSTAMP:20251210T045840Z
SUMMARY:Learning to Model: Constraint Acquisition via Queries and Symbolic
 –Connectionist Hybridization
DESCRIPTION:Speaker: Nadjib Lazaar (University of Paris-Saclay)\n\nAbstract
 : \n\nConstraint Acquisition (CA) is a symbolic learning framework at the 
 intersection of concept learning (inductive reasoning) and constraint prog
 ramming (deductive reasoning). These two paradigms\, rooted in symbolic AI
 \, are combined in CA to automate and accelerate the modeling phase\, enab
 ling the automatic construction of constraint networks representing a targ
 et concept.\nIn Query-Based Constraint Acquisition (QBCA)\, the learner in
 teracts actively with an oracle by posing structured queries\, progressive
 ly refining the hypothesis space. This talk provides a structured overview
  of QBCA\, with a focus on the typology of queries (e.g.\, membership quer
 ies\, equivalence queries) and their role in the acquisition process. I wi
 ll also cover theoretical foundations\, recent algorithmic developments\, 
 and extensions to partial\, uncertain\, or qualitative contexts. QBCA open
 s promising avenues in applications such as program analysis\, autonomous 
 systems\, and interactive explainable modeling in XAI.\nFinally\, I will d
 iscuss emerging connections between QBCA and contemporary connectionist ap
 proaches\, notably language models (LLMs) and Transformers\, outlining dir
 ections for integrating explicit symbolic reasoning with statistical learn
 ing capabilities.\n \nShort Bio:Nadjib Lazaar is a Full Professor at Pari
 s-Saclay University and a member of the LaHDAK team at the LISN laboratory
 . He currently serves as director of the MIAGE program and co-director of 
 the Master's in Data Science at the Faculty of Sciences of Orsay. He is al
 so the International Relations Officer for the DATAIA Institute and the AI
  Cluster. Previously\, he was an Associate Professor (HDR) at the Universi
 ty of Montpellier from 2013 to 2024. His research sits at the intersection
  of Constraint Programming\, Data Mining\, Machine Learning\, and Software
  Engineering\, with a focus on constraint acquisition\, declarative data m
 ining\, AI-based software testing\, and trustworthy neuro-symbolic AI.\n
URL:https://www.tcs.tifr.res.in/web/events/1647
DTSTART;TZID=Asia/Kolkata:20251210T160000
DTEND;TZID=Asia/Kolkata:20251210T170000
LOCATION:HBA Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1622
DTSTAMP:20251208T054637Z
SUMMARY:Fourier Analysis on finite Abelian groups and its Applications
DESCRIPTION:Speaker: Swarnalipa Datta (ISI Kolkata)\n\nAbstract: \n\nA Bool
 ean-valued function is a map from a domain D to a range of cardinality two
 \, such as {−1\, +1}\, or {0\, 1}. These functions play a central role i
 n theoretical computer science\, additive combinatorics\, and several othe
 r areas. When the domain D is equipped with an algebraic structure\, parti
 cularly that of a finite Abelian group\, Boolean-valued functions become e
 specially important for studying algorithms and complexity. Such settings 
 allow us to investigate the Fourier analysis of Boolean functions\, examin
 e the structure of their Fourier spectra\, and understand the behavior of 
 their Fourier coefficients.Most prior work has focused on the case D=Z_2^n
 \, the space of binary strings of length n. A natural question is whether 
 these results extend to Boolean-valued functions defined over arbitrary fi
 nite Abelian groups. This talk will address several problems that we have 
 generalized to this broader setting.Granularity: The Fourier sparsity s_f 
 of f is the number of nonzero Fourier coefficients. When s_f is small\, wh
 at can be said about the magnitude of the Fourier coefficients? Gopalan et
  al. (2011) showed that for Boolean functions on Z_2^n\, every nonzero Fou
 rier coefficient has absolute value at least 1/s_f.Upper bounds on Fourier
  dimension: The Fourier dimension r_f is the dimension of the Fourier supp
 ort of f. Sanyal (2019) proved that r_f = O(\\sqrt{s_f} log s_f ). This wa
 s improved by Chakraborty et al. (2020)\, who showed that r_f = O(\\sqrt{s
 _f \\delta_f} log s_f )\, where \\delta_f = Pr_x[f(x) = −1]. These resul
 ts demonstrate that Boolean functions with small sparsity cannot have arbi
 trarily large Fourier dimension. Improved bounds for Chang's lemma and Coh
 en's idempotent theorem have also been obtained in the Z_2^n setting.\n \
 nPage 1 of 2.... \n \n \n \n \n \nContinued from Page 1...\nLinear I
 somorphism Testing: The linear isomorphism testing problem for Boolean fun
 ctions over Z_2^n is also an important area of study. For A \\in Z_2^n×n\
 , let f ◦ A : Z_2^n → {−1\, 1} be the function f ◦A(x) = f(Ax) fo
 r all x ∈ Z_2^n. The Linear Isomorphism Distance between f : Z_2^n → 
 {−1\, 1} and g : Z_2^n → {−1\, 1} is defined as dist_{Z_2^n}(f\, g)
  = min_{A\\in Z_2^{n×n}: A is non-singular} \\delta(f ◦A\, g). Assume t
 hat f and g satisfy the promise that either dist_{Z_2^n}(f\, g)=0 or dist_
 {Z_2^n}(f\, g) \\geq \\epsilon\, the question of Linear Isomorphism testin
 g is that of deciding which is the case. \n \nAdditional investigations 
 include the approximate degree of Boolean functions\, the Fourier–Entrop
 y Influence (FEI) conjecture\, and related topics. A key challenge in exte
 nding results from Z_2^n to arbitrary finite Abelian groups is that genera
 l Abelian groups are not vector spaces\, and their Fourier coefficients ar
 e complex numbers. Consequently\, many structural properties used in the Z
 _2^n setting break down\, making such generalizations nontrivial. The talk
  will highlight these challenges and discuss the main obstacles to develop
 ing analogous results over finite Abelian groups.\n \nThe talk is based o
 n the following works:\n(1) On Fourier analysis of sparse Boolean functio
 ns over certain Abelian groups [Chakraborty\, Datta\, Dutta\, Ghosh\, San
 yal]\, MFCS 2024\n(2) Testing Isomorphism of Boolean Functions over Fini
 te Abelian Groups [Datta\, Ghosh\, Kayal\, Paraashar\, Roy]\, RANDOM 2025
 \n(3) Structure of Sparse Boolean Functions over Abelian Groups\, and its
  Application to Testing [Chakraborty\, Datta\, Dutta\, Ghosh\, Sanyal]\n(
 4) No Vector Space? No Problem: Lifting Boolean Function Results to Abeli
 an Groups [Chakraborty\, Datta\, Ghosh\, Sanyal]\nShort Bio:I am a Senior
  Research Fellow in computer science\, currently working at the Indian Sta
 tistical Institute\, Kolkata under the supervision of Dr. Sourav Chakrabor
 ty and Dr. Arijit Ghosh\, on Fourier analysis of Boolean functions. I have
  done my bachelors and masters from St. Xavier's college\, Kolkata and Ind
 ian Institute of Science\, Bangalore respectively\, in mathematics.\n \n
  \n \n \n \n \n \n \n \n \n \n \n \nPage 2 of 2.\n
URL:https://www.tcs.tifr.res.in/web/events/1622
DTSTART;TZID=Asia/Kolkata:20251211T160000
DTEND;TZID=Asia/Kolkata:20251211T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1629
DTSTAMP:20251211T091547Z
SUMMARY:Sublinear-Time Lower Bounds for Approximating Matching Size using N
 on-Adaptive Queries
DESCRIPTION:Speaker: Vihan Shah (University of Birmingham)\n\nAbstract: \nW
 e study the problem of estimating the size of the maximum matching in the 
 sublinear-time setting. This problem has been extensively studied\, with s
 everal known upper and lower bounds. A notable result by Behnezhad (FOCS 2
 021) established a 2-approximation in O~(n) time.\nHowever\, all known upp
 er and lower bounds are in the adaptive query model\, where each query can
  depend on previous answers. In contrast\, non-adaptive query models—whe
 re the distribution over all queries must be fixed in advance—are widely
  studied in property testing\, often revealing fundamental gaps between ad
 aptive and non-adaptive complexities. This raises the natural question: is
  adaptivity also necessary for approximating the maximum matching size in 
 sublinear time? This motivates the goal of achieving a constant or even a 
 polylogarithmic approximation using O~(n) non-adaptive adjacency list quer
 ies\, similar to what was done by Behnezhad using adaptive queries.\nWe sh
 ow that this is not possible by proving that any randomized non-adaptive a
 lgorithm achieving an n^{1/3 - gamma}-approximation\, for any constant gam
 ma > 0\, with probability at least 2/3\, must make Omega(n^{1 + eps}) adja
 cency list queries\, for some constant eps > 0 depending on gamma. This re
 sult highlights the necessity of adaptivity in achieving strong approximat
 ions. However\, non-trivial upper bounds are still achievable: we present 
 a simple randomized algorithm that achieves an n^{1/2}-approximation in O(
 n \\log n) queries.\nShort Bio:Vihan Shah is a Postdoctoral Researcher at 
 the University of Birmingham\, working with Sagnik Mukhopadhyay in the The
 ory of Computation group. He received his PhD from the University of Water
 loo\, advised by Sepehr Assadi. His research focuses on graph algorithms i
 n modern models of computation such as streaming\, sublinear-time\, and dy
 namic settings.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1629
DTSTART;TZID=Asia/Kolkata:20251215T160000
DTEND;TZID=Asia/Kolkata:20251215T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1656
DTSTAMP:20251215T055054Z
SUMMARY:Sparsifying suprema of Gaussian processes
DESCRIPTION:Speaker: Anindya De (University of Pennsylvania)\n\nAbstract: \
 nWe show that the supremum of any centered Gaussian processcan be approxim
 ated to any arbitrary accuracy by a finite dimensional Gaussian process\,
  where the dimension of the approximator is justdependent on the target er
 ror. As a corollary\, we show that for any norm \\Phi defined over R^n an
 d target error \\eps\, there is a norm \\Psi such that (i) \\Psi is only 
 dependent on t(\\eps) = \\exp (\\exp(poly(1/\\eps))) dimensions and (ii) \
 \Psi(x)/\\Phi(x) \\in [1-\\eps\, 1+\\eps] with probability 1-\\eps (when x
  is sampled from the Gaussianspace). We prove a similar-in-spirit result f
 or sparsifying high-dimensional polytopes in Gaussian space\, and present
  applications to computational learning and property testing. Our proof r
 elies on Talagrand's majorizing measures theorem.\nJoint work with Shivam
  Nadimpalli\, Ryan O'Donnell and Rocco Servedio.\n
URL:https://www.tcs.tifr.res.in/web/events/1656
DTSTART;TZID=Asia/Kolkata:20251216T160000
DTEND;TZID=Asia/Kolkata:20251216T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1661
DTSTAMP:20251218T072638Z
SUMMARY:MSc Project Seminar
DESCRIPTION:Speaker: Spandan Poddar (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1661
DTSTART;TZID=Asia/Kolkata:20251219T110000
DTEND;TZID=Asia/Kolkata:20251219T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1660
DTSTAMP:20251218T072659Z
SUMMARY:MSc Project Seminar
DESCRIPTION:Speaker: Nishant Das (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1660
DTSTART;TZID=Asia/Kolkata:20251219T140000
DTEND;TZID=Asia/Kolkata:20251219T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1659
DTSTAMP:20251218T072714Z
SUMMARY:MSc Project Seminar
DESCRIPTION:Speaker: Aindrila Rakshit (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1659
DTSTART;TZID=Asia/Kolkata:20251219T170000
DTEND;TZID=Asia/Kolkata:20251219T180000
LOCATION:A-238
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1642
DTSTAMP:20251223T034850Z
SUMMARY:The Robustness of Top Trading Cycles: Uniqueness in the Probabilist
 ic Setup
DESCRIPTION:Speaker: Soumyarup Sadhukhan (IIT Kanpur)\n\nAbstract: \nThe as
 signment problem with initial endowments (the "housing market") is a corne
 rstone of mechanism design. In the deterministic setting\, Ma (1994) famou
 sly characterized the Top Trading Cycles (TTC) rule as the unique mechanis
 m that satisfies strategy-proofness\, Pareto efficiency\, and individual r
 ationality.\nIn this talk\, I explore whether expanding the domain to prob
 abilistic assignments allows for new\, perhaps fairer\, mechanisms. While 
 randomization often bypasses impossibility results in mechanism design\, w
 e show a striking "collapse" in the housing market. We prove that if agent
 s have deterministic initial endowments\, TTC remains the only admissible 
 rule\, even under the weakest notions of strategy-proofness and efficiency
  extended to lotteries. I will detail this characterization\, discuss some
  known impossibility results for probabilistic endowments for more than th
 ree agents\, and conclude with some open problems in the design of exchang
 e mechanisms.\nShort Bio:\nDr. Soumyarup Sadhukhan is an Assistant Profess
 or in the Department of Mathematics and Statistics at the Indian Institute
  of Technology (IIT) Kanpur. His primary research interests lie at the int
 ersection of mathematics and economics\, specifically in Game Theory\, Mec
 hanism Design\, and Choice Theory.\nDr. Sadhukhan earned his PhD from the 
 Economic Research Unit of the Indian Statistical Institute (ISI)\, Kolkata
 \, where his thesis focused on probabilistic mechanism design. Prior to jo
 ining IIT Kanpur\, he served as a C.V. Raman Post-doctoral Fellow at the D
 epartment of Computer Science and Automation\, Indian Institute of Science
  (IISc)\, Bangalore.\nHis current work explores the axiomatic foundations 
 of resource allocation\, with a focus on probabilistic assignment problems
  and fair division. His research has been published in reputable journals\
 , including the Journal of Economic Theory\, Journal of Mathematical Econo
 mics\, and Mathematics of Operations Research.\n
URL:https://www.tcs.tifr.res.in/web/events/1642
DTSTART;TZID=Asia/Kolkata:20251223T160000
DTEND;TZID=Asia/Kolkata:20251223T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1658
DTSTAMP:20251219T042011Z
SUMMARY:Depth-2 threshold circuits and related models of computation
DESCRIPTION:Speaker: Vladimir Podolskii (Tufts University)\n\nAbstract: \nL
 ow-depth Boolean threshold circuits play an important role in theoretical 
 computer science. On one hand\, they are central for some of the main curr
 ent frontiers in Boolean circuit complexity\, and on the other hand they f
 orm a Boolean version of feed-forward neural networks. It turns out that p
 roving lower bounds for these Boolean circuits is notoriously hard: lower 
 bounds for explicit functions are unknown even for depth-2 circuits. In ot
 her words\, we do not understand well the expressibility of feed-forward n
 eural networks with just one hidden layer.In this talk we will discuss kno
 wn approaches to this problem\, subproblems that also remain open\, and so
 me recent progress on them. In particular\, we will discuss other computat
 ional models that turn out to be related to this setting\, including model
 s based on decision lists and models based on nearest neighbour representa
 tion of Boolean functions.The talk is based on joint work with Mason DiCic
 co\, Daniel Reichman and Morgan Prior. I will also mention some older resu
 lts of joint work with Kristoffer Arnsfelt Hansen.\nShort Bio:\nVladimir P
 odolskii is a theoretical computer scientist working in computational comp
 lexity. He is currently an associate professor at Tufts University. Prior 
 to that he has worked at Steklov Mathematical Institute in Moscow since 20
 09 as research scientist. From 2014 till 2022 he also worked at HSE Univer
 sity in Moscow as an associate professor (part-time). From 2022 till 2023 
 we worked as visiting associate professor at Courant Institute\, NYU. He r
 eceived his PhD from Moscow State University in 2009.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1658
DTSTART;TZID=Asia/Kolkata:20251224T110000
DTEND;TZID=Asia/Kolkata:20251224T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1644
DTSTAMP:20251230T040224Z
SUMMARY:Lattice packing of spheres in high dimensions using a stochasticall
 y evolving ellipsoid
DESCRIPTION:Speaker: Boaz Klartag (The Weizmann Institute of Science)\n\nAb
 stract: \nWe prove that in any dimension n there exists an origin-symmetri
 c ellipsoid of volume $c n^2$ that contains no points of $Z^n$ other than 
 the origin. Here $c > 0$ is a universal constant. Equivalently\, there exi
 sts a lattice sphere packing in $R^n$ whose density is at least $c n^2 / 2
 ^n$. Previously known constructions of sphere packings in $R^n$ had densit
 ies of the order of magnitude of $n / 2^n$\, up to logarithmic factors. Ou
 r proof utilizes a stochastically evolving ellipsoid that accumulates at l
 east  $c n^2$ lattice points on its boundary\, while containing no lattic
 e points in its interior except for the origin.\nShort Bio:Boaz Klartag 
 is a professor in the Department of Mathematics at the Weizmann Institute 
 of Science. He obtained his PhD in 2004 from Tel Aviv University under t
 he supervision of Prof. Vitali Milman. His research interests lie in conve
 x geometry\, analysis\, and high-dimensional phenomena. Klartag's contrib
 utions include his work on the central limit theorem for convex sets\, Bou
 rgain's slicing problem\, needle decompositions in Riemannian geometry\, a
 nd the approximation of data by C^m-smooth functions. He has received nume
 rous accolades\, including the European Mathematical Society (EMS) Prize\,
  the Salem Prize\, and the Erdős Prize. Before joining Weizmann\, he held
  faculty positions at Princeton University and Tel Aviv University and was
  a Clay Research Fellow as well as a member of the Institute for Advanced 
 Study. He has also held visiting positions at the Fondation Sciences Math
 ématiques de Paris (FSMP)\, the Mathematical Sciences Research Institute 
 (MSRI)\, the Fields Institute at the University of Toronto\, Princeton Uni
 versity\, and ETH Zurich. \n
URL:https://www.tcs.tifr.res.in/web/events/1644
DTSTART;TZID=Asia/Kolkata:20251230T123000
DTEND;TZID=Asia/Kolkata:20251230T133000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1663
DTSTAMP:20251229T081051Z
SUMMARY:R. Narasimhan Workshop 2026
DESCRIPTION:Speaker: \n\nAbstract: \nWebsite: R. Narasimhan Workshop 2026 
 — TIFR Mumbai\n
URL:https://www.tcs.tifr.res.in/web/events/1663
DTSTART;VALUE=DATE:20260105
DTEND;VALUE=DATE:20260107
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1662
DTSTAMP:20251230T044235Z
SUMMARY:Algorithmically Testing Sub-Gaussianity of High Dimensional Distrib
 utions
DESCRIPTION:Speaker: Ankit Pensia (CARNEGIE MELLON UNIVERSITY\, USA)\n\nAbs
 tract: \nSub-Gaussian distributions play a central role in statistics\, pr
 obability\, and computer science. A distribution is termed sub-Gaussian i
 f all of its univariate projections have tails that decay faster than a Ga
 ussian. In algorithmic statistics\, a central task is the following: give
 n samples from a distribution\, decide whether the underlying distribution
  is sub-Gaussian or heavy-tailed. In high dimensions\, this is a challeng
 ing problem because sub-Gaussianity requires all univariate projections to
  be light-tailed\, which seemingly necessitates a brute-force search over 
 directions to verify. In this talk\, I will describe a structural propert
 y of sub-Gaussian distributions that leads to computationally efficient al
 gorithms for a wide range of statistical problems\, e.g.\, clustering\, ro
 bust estimation\, and more. Based on joint work with Ilias Diakonikolas\,
  Sam Hopkins\, and Stefan Tiegel.\n \nShort Bio: Ankit Pensia is an assis
 tant professor in the Department of Statistics and Data Science at Carnegi
 e Mellon University. Previously\, he was a research fellow at the Simons I
 nstitute for the Theory of Computing and a Herman Goldstine Postdoctoral F
 ellow at IBM Research. He obtained his PhD in Computer Science from the Un
 iversity of Wisconsin-Madison. His current research interests include algo
 rithmic robust statistics\, high-dimensional probability\, distribution te
 sting\, and algorithmic stability.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1662
DTSTART;TZID=Asia/Kolkata:20260107T110000
DTEND;TZID=Asia/Kolkata:20260107T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1636
DTSTAMP:20251216T064340Z
SUMMARY:A Cautionary Note on Quantum Oracles
DESCRIPTION:Speaker: Avantika Agarwal (University of Waterloo)\n\nAbstract:
  \nIn recent years\, the quantum oracle model introduced by Aaronson and K
 uperberg (2007) has found a lot of use in showing oracle separations betwe
 en complexity classes and cryptographic primitives. It is generally assume
 d that proof techniques that do not relativize with respect to quantum ora
 cles will also not relativize with respect to classical oracles. In this n
 ote\, we show that this is not the case: specifically\, we show that there
  is a quantum oracle problem that is contained in the class QMA\, but not 
 in a class we call polyQCPH. The class polyQCPH is equal to PSPACE with re
 spect to classical oracles\, and it is a well-known result that QMA is con
 tained in PSPACE (also with respect to classical oracles).We also show tha
 t the same separation holds relative to a distributional oracle\, which is
  a model introduced by Natarajan and Nirkhe (2024). We believe our finding
 s show the need for some caution when using these non-standard oracle mode
 ls\, particularly when showing separations between quantum and classical r
 esources.\nThis talk is based on joint work with Srijita Kundu.\n \nShort
  Bio:  I am a PhD student at Institute for Quantum Computing\, University
  of Waterloo. My advisors are Prof. Shalev Ben-David and Prof. Eric Blais.
  I am interested in complexity theory and quantum information. Previously 
 I was an undergraduate student at IIT Delhi\, where I was advised by Prof.
  Venkata Koppula.\n
URL:https://www.tcs.tifr.res.in/web/events/1636
DTSTART;TZID=Asia/Kolkata:20260107T160000
DTEND;TZID=Asia/Kolkata:20260107T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1632
DTSTAMP:20251230T040624Z
SUMMARY:Generating Useful Randomness from Block Sources
DESCRIPTION:Speaker: Eshan Chattopadhyay (Cornell University)\n\nAbstract: 
 \nWe consider the problem of generating high-quality random bits from a st
 ream of blocks\, where the 'good blocks' carry entropy but  'bad blocks' 
 may be correlated with the good ones. I will describe recent progress on t
 his problem\, highlight several open questions\, and discuss interesting c
 onnections to Boolean function analysis and fault-tolerant distributed com
 puting.\nBased on joint works with Mohit Gurumukhani\, Noam Ringach and
  Rocco Servedio. \n \nShort bio: Eshan Chattopadhyay is an Associate Pro
 fessor of Computer Science at Cornell University. His research in theoreti
 cal computer science focuses on use of randomness in computation\, computa
 tional complexity\, and cryptography.\n
URL:https://www.tcs.tifr.res.in/web/events/1632
DTSTART;TZID=Asia/Kolkata:20260108T160000
DTEND;TZID=Asia/Kolkata:20260108T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1667
DTSTAMP:20260109T040525Z
SUMMARY:Memory Complexity of Bunary Hypothesis Testing.
DESCRIPTION:Speaker: Malhar Ajit  Managoli (TIFR)\n\nAbstract: \nIn many st
 atistical problems\, sample complexity\, i.e. number of samples required t
 o keep the error below a threshold\, is quantity of central importance. In
  this talk\, we will see an introduction to a slightly different model in 
 which samples are plentiful\, but the memory available to the computer is 
 limited. Specifically\, we will consider binary hypothesis testing under a
  limited memory framework\, modeled via a finite automaton. We will define
  the concept of memory complexity\, analogous to sample complexity\, and s
 how that the memory limited probability of error decays exponentially in t
 he number of states of our automaton\, similar to the exponential decay in
  the number of samples of the probability of error in the usual model.Base
 d on Hellman&Cover 1969.\n
URL:https://www.tcs.tifr.res.in/web/events/1667
DTSTART;TZID=Asia/Kolkata:20260109T160000
DTEND;TZID=Asia/Kolkata:20260109T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1653
DTSTAMP:20260105T044829Z
SUMMARY:Infinitely divisible privacy and beyond I: resolution of the s^2=2k
  conjecture
DESCRIPTION:Speaker: Aaradhya Pandey (Princeton University)\n\nAbstract: \n
 In this talk\, I will begin by introducing a hypothesis-testing-based form
 ulation of differential privacy in classical computation. The Gaussian Dif
 ferential Privacy paper (Dong–Roth–Su '22) established a central limit
  theorem for the composition of multiple private mechanisms. Building on t
 his\, I will present a Poisson extension of their result and show how both
  the Gaussian and Poisson limits are unified under the framework of infin
 itely divisible privacy\, revealing connections to statistics\, probabilit
 y\, and discrete mathematics. I will conclude with discussions on quantiz
 ing privacy in quantum computation and deriving central limit theorems in
  a framework of quantum differential privacy.\n \nShort Bio:  Aaradhya 
 is a fifth-year PhD Student at Princeton ORFE. He completed his Bachelor's
  in mathematics at IISc in 2021. His research interests are at the interfa
 ce of probability theory\, statistics\, and information theory with ap
 plications in (quantum) differential privacy\, machine unlearning\, and
  spin glasses. When most approaches in a field are analytic\, he tries to
  develop algebraic ones — and vice versa.\n
URL:https://www.tcs.tifr.res.in/web/events/1653
DTSTART;TZID=Asia/Kolkata:20260113T160000
DTEND;TZID=Asia/Kolkata:20260113T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1655
DTSTAMP:20260108T112202Z
SUMMARY:Verified Programming Frameworks for Authenticated Data Structures
DESCRIPTION:Speaker: Chaitanya Agarwal (Courant Institute of Mathematical S
 ciences\, New York University)\n\nAbstract: \nAuthenticated data structure
 s (ADSs) allow untrusted third parties to carry out operations which produ
 ce proofs that can be used to verify an operation's output. Such data stru
 ctures are challenging to develop and implement correctly. In this talk\, 
 I will talk about programming frameworks that exploit some structural prop
 erties of ADSs to make the task of correctly implementing ADSs easier: (1)
  lambda-auth - a domain-specific extension of the OCaml programming langua
 ge\, that generates correct and secure ADS binaries automatically\; (2) Au
 thentikit - a library version of lambda-auth currently implemented in OCam
 l. I will also talk about recent work by us (https://dl.acm.org/doi/abs/10
 .1145/3719027.3744801) that gives a formal proof of security and correctne
 ss of Authentikit.\nShort Bio:Chaitanya Agarwal (https://culechetoo.github
 .io) is a 3rd year computer science PhD student at the New York University
 \, advised by Joseph Tassarotti. He is broadly interested in programming l
 anguages and formal verification with a particular focus on verification o
 f security applications. In the past\, he has also worked with Thomas Wies
  on abstract-interpretation analysis for recursive\, higher-order programs
 \, and with Shibashis Guha\, on developing statistical-model-checking tech
 niques for Markov Decision Processes (MDPs). Chaitanya obtained his B.Tech
 . from IIIT Delhi.\n
URL:https://www.tcs.tifr.res.in/web/events/1655
DTSTART;TZID=Asia/Kolkata:20260114T110000
DTEND;TZID=Asia/Kolkata:20260114T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1657
DTSTAMP:20251216T064710Z
SUMMARY:Optimal Proximity Gaps for Subspace-Design Codes and (Random) Reed-
 Solomon Codes
DESCRIPTION:Speaker: Rohan Goyal (MIT)\n\nAbstract: \nReed-Solomon (RS) cod
 es were recently shown to exhibit an intriguing \\emph{proximity gap} phen
 omenon. Specifically\, given a collection of strings with some algebraic s
 tructure (such as belonging to a line or affine space)\, either all of the
 m are $\\delta$-close to RS codewords\, or most of them are $\\delta$-far 
 from the code. Here  $\\delta$ is the proximity parameter which can be ta
 ken to be the Johnson radius $1-\\sqrt{R}$ of the RS code ($R$ being the c
 ode rate)\, matching its best known list-decodability. Proving proximity g
 aps beyond the Johnson radius\, and in particular approaching $1-R$ (which
  is best possible)\, has been posed multiple times as a challenge with sig
 nificant practical consequences to the efficiency of SNARKs. In this work\
 , we show that most codes in the literature that have been shown to achiev
 e list-decoding capacity\, i.e.\, are \\emph{list-decodable} up to a fract
 ion of errors approaching $1-R$\, exhibit proximity gaps for $\\delta<1-R$
 . This includes folded Reed-Solomon codes\, univariate multiplicity codes\
 , random linear codes\, and random Reed-Solomon codes. Based on joint work
  with Venkatesan Guruswami.\nShort Bio: Rohan is a PhD student in the Theo
 ry of Computation Group at MIT\, where he is advised by Yael Tauman Kalai.
  His research interests are broadly in error correction\, proof systems\, 
 and more generally theoretical CS. Rohan has been a friend of STCS since h
 is undergraduate days\, when he spent a few months here as an intern. \n
URL:https://www.tcs.tifr.res.in/web/events/1657
DTSTART;TZID=Asia/Kolkata:20260114T160000
DTEND;TZID=Asia/Kolkata:20260114T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1654
DTSTAMP:20260116T044231Z
SUMMARY:The Landscape of Exact Round Complexity in Secure Multi-Party Compu
 tation
DESCRIPTION:Speaker: Arpita Patra (IISC Bangalore)\n\nAbstract: \n\nSecure 
 Multi-Party Computation (MPC) is a central problem in cryptography\, often
  regarded as its holy grail. It enables a group of mutually distrusting da
 ta owners to jointly compute a function over their private inputs\, while 
 revealing nothing beyond what is inherently implied by the output itself.\
 nRound complexity is one of the most fundamental efficiency measures in MP
 C\, capturing the minimal interaction required for secure computation. In 
 this talk\, I will present a high-level overview of the evolution of resea
 rch on round complexity in MPC and place my own contributions within this 
 evolving landscape.\nShort Bio:Arpita Patra is currently a Professor of Co
 mputer Science at the Indian Institute of Science (IISc). Her research int
 erests lie in cryptography\, with a specific focus on both the theoretical
  foundations and practical applications of secure multiparty computation p
 rotocols. She earned her Ph.D. from the Indian Institute of Technology (II
 T) Madras and subsequently held postdoctoral positions at leading institut
 ions including the University of Bristol (UK)\, ETH Zurich (Switzerland)\,
  and Aarhus University (Denmark).Her contributions have been recognized th
 rough numerous honors\, including: Prof. S. K. Chatterjee Award for Outsta
 nding Woman Researcher/Industry Leader by IISc (2023)\; Google Privacy Res
 earch Faculty Award (2023)\; J.P. Morgan Chase Faculty Award (2022)\; SONY
  Faculty Innovation Award (2021)\; Google Research Award (2020)\; NASI You
 ng Scientist Platinum Jubilee Award (2018)\; SERB Women Excellence Award (
 2016)\; INAE Young Engineer Award (2016).  She is also affiliated with es
 teemed scientific bodies including the Indian Academy of Sciences (IAS)\, 
 the Indian National Academy of Engineering (INAE)\, and The World Academy 
 of Sciences (TWAS). In addition to her research\, she has coauthored two a
 cademic textbooks:Secure Multiparty Computation against Passive Adversarie
 s (Springer\, 2023)Fault Tolerant Distributed Consensus in Synchronous Net
 works (Springer\, 2025)\n
URL:https://www.tcs.tifr.res.in/web/events/1654
DTSTART;TZID=Asia/Kolkata:20260116T110000
DTEND;TZID=Asia/Kolkata:20260116T120000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1671
DTSTAMP:20260116T054445Z
SUMMARY:Fast exact algorithms via the Matrix Tree Theorem
DESCRIPTION:Speaker: Shanthanu S. Rai (TIFR)\n\nAbstract: \nCounting Hamilt
 onian paths in graphs and perfect matchings in bipartite graphs are well k
 nown hard problems. In this talk\, we will use a seemingly innocuous resul
 t to provide the best known upper bounds for these two hard to compute obj
 ects\, along with some of their restrictions and variants. The result we u
 se is the so called Matrix Tree Theorem\, which counts the number of spann
 ing trees in the graph by reducing it to a single determinant computation.
 If time permits\, we will also see fast exact algorithms for finding Hamil
 tonian paths in bipartite graphs. For all of the algorithms\, we will see 
 a common recipe using the Matrix Tree Theorem.Paper link: https://arxiv.o
 rg/pdf/2512.08600\n
URL:https://www.tcs.tifr.res.in/web/events/1671
DTSTART;TZID=Asia/Kolkata:20260116T160000
DTEND;TZID=Asia/Kolkata:20260116T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1672
DTSTAMP:20260119T040003Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Aakash Ghosh (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1672
DTSTART;TZID=Asia/Kolkata:20260119T163000
DTEND;TZID=Asia/Kolkata:20260119T173000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1640
DTSTAMP:20260119T062659Z
SUMMARY:Old dog\, Old tricks\, New show: Fast preconditioned 1st order meth
 ods for training Kernel Machines
DESCRIPTION:Speaker: Parthe Pandit (IIT Bombay)\n\nAbstract: \nKernel Machi
 nes are a classical family of models in Machine Learning that overcome sev
 eral limitations of Neural Networks. These models have regained popularity
  following some landmark results showing their equivalence to Neural Netwo
 rks. I will present a suite of training algorithms for this family of mode
 ls based on preconditioned stochastic gradient descent in the Reproducing 
 Kernel Hilbert Space (RKHS). These algorithms\, called EigenPro\, are stat
 e of the art for training of Kernel Machines at scale. They have enabled t
 he training of very large models with arbitrarily large datasets. \n \nS
 hort Bio:  Parthe Pandit is a Thakur Family Chair Assistant Professor at 
 C-MInDS\, IIT Bombay. He was a Simons postdoctoral fellow at UC San Diego\
 , obtained his PhD and MS from UCLA\, and his undergraduate education from
  IIT Bombay. He received the AI2050 Early Career Fellowship from Schmidt S
 ciences in 2024\, and the Jack K Wolf Student Paper Award at ISIT 2019.\n
URL:https://www.tcs.tifr.res.in/web/events/1640
DTSTART;TZID=Asia/Kolkata:20260120T160000
DTEND;TZID=Asia/Kolkata:20260120T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1674
DTSTAMP:20260121T050020Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Vivek Karunakaran (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1674
DTSTART;TZID=Asia/Kolkata:20260121T140000
DTEND;TZID=Asia/Kolkata:20260121T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1675
DTSTAMP:20260122T084352Z
SUMMARY:Aggregating maximal cliques in real-world graphs
DESCRIPTION:Speaker: Sabyasachi Basu (Microsoft Research)\n\nAbstract: \nMa
 ximal clique enumeration is a fundamental graph mining task\, but its util
 ity is often limited by computational intractability and highly redundant 
 output. To address these challenges\, we introduce $\\rho$-dense aggregato
 rs\, a novel approach that succinctly captures maximal clique structure. I
 nstead of listing all cliques\, we identify a small collection of clusters
  with edge density at least $\\rho$ that collectively contain every maxima
 l clique.In contrast to maximal clique enumeration\, we prove that for all
  $\\rho < 1$\, every graph admits a $\\rho$-dense aggregator of sub-expone
 ntial size\, $n^{O (\\log 1/\\rho n)}$\, and provide an algorithm achievin
 g this bound. For graphs with bounded degeneracy\, a typical characteristi
 c of real-world networks\, our algorithm runs in near-linear time and prod
 uces near-linear size aggregators. We also establish a matching lower boun
 d on aggregator size\, proving our results are essentially tight. In an em
 pirical evaluation on real-world networks\, we demonstrate significant pra
 ctical benefits for the use of aggregators: our algorithm is consistently 
 faster than the state-of-the-art clique enumeration algorithm\, with media
 n speedups over 6$\\times$ for $\\rho = 0.1$ (and over 300$\\times$ in an 
 extreme case)\, while delivering a much more concise structural summary.Ba
 sed on joint work with Noga Alon\, Shweta Jain\, Haim Kaplan\, Jakub Lacki
 \, and Blair D. Sullivan.\nShort Bio: Sabyasachi Basu is a postdoctoral re
 searcher at Microsoft Research India\, where he works with the vector sear
 ch team (DiskANN) on problems in quantization and retrieval. He earned his
  PhD in Computer Science from the University of California\, Santa Cruz\, 
 where he worked with C. Seshadhri on sublinear algorithms and graph decomp
 ositions. Previously\, he completed his undergraduate studies in Mathemati
 cs at IISc Bangalore. His research interests include using theoretical ins
 ights to design algorithms for real-world data and exploring theoretical q
 uestions arising from empirical observations.\n
URL:https://www.tcs.tifr.res.in/web/events/1675
DTSTART;TZID=Asia/Kolkata:20260123T140000
DTEND;TZID=Asia/Kolkata:20260123T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1666
DTSTAMP:20260120T085032Z
SUMMARY:Oral Qualifier
DESCRIPTION:Speaker: Spandan Poddar (TIFR)\n\nAbstract: \n\n
URL:https://www.tcs.tifr.res.in/web/events/1666
DTSTART;TZID=Asia/Kolkata:20260123T160000
DTEND;TZID=Asia/Kolkata:20260123T170000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1665
DTSTAMP:20260121T034650Z
SUMMARY:The PCP Theorem with a Single Composition
DESCRIPTION:Speaker: Amik Raj Behera (University of Copenhagen)\n\nAbstract
 : \nA Probabilistically Checkable Proof (PCPs) is a proof system with a pr
 obabilistic verifier that queries the given proof and either accepts or re
 jects. One would like to minimize the number of random bits and the number
  of queries made by the verifier. PCPs are a generalization of the complex
 ity class NP. In fact\, a celebrated result of Arora\, Lund\, Motwani\, Su
 dan\, Szegedy characterized NP by a PCP with O(log n) randomness and const
 ant queries\, which is known as the PCP Theorem.\nIn this work\, we give a
  new and a simpler proof of the PCP Theorem by constructing a class of PCP
 s with range of parameters which was not known before. To achieve this\, w
 e introduce "Zero-on-Variety Test"\, which acts as an alternative to sum-c
 heck protocols. Finally\, to get a PCP of our choice of parameters\, we ap
 ply the Zero-on-Variety test on subsets related to Boolean slices. Our new
  protocols build on ideas from the theory of Gröbner bases.\nThis is base
 d on a joint work with Prashanth Amireddy\, Srikanth Srinivasan\, Madhu Su
 dan\, and Sophus Valentin Willumsgaard\, and can be found here: https://e
 ccc.weizmann.ac.il/report/2025/165/\nShort Bio :  Amik Raj Behera is a Ph
 .D. student at the University of Copenhagen under the guidance of Prof. Sr
 ikanth Srinivasan. He did his master's at Aarhus University and bachelor's
  at the Chennai Mathematical Institute. His research interests are in comp
 lexity theory\, coding theory\, and problems with an algebraic flavor.\n
URL:https://www.tcs.tifr.res.in/web/events/1665
DTSTART;TZID=Asia/Kolkata:20260127T160000
DTEND;TZID=Asia/Kolkata:20260127T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1668
DTSTAMP:20260127T140147Z
SUMMARY:Synthesis of Full-Information Protocols
DESCRIPTION:Speaker: Dietmar Berwanger (Université Paris-Saclay\, CNRS\, E
 NS Paris-Saclay)\n\nAbstract: \nIn this talk I will discuss a simple\, but
  powerful way to think about communication in distributed systems: wheneve
 r two (or more) processes interact\, they dump all of their current local 
 knowledge to each other. This full‑information view\, standard in distri
 buted computing\,  becomes subtle once we admit an undetermined environme
 nt that decides when communication happens and who participates. From the 
 perspective of an individual process\, a single interaction can then conve
 y an arbitrarily large amount of information\, so the traditional automata
 -theoretic approach breaks down.\nTo analyse such systems\, we model them 
 as infinitely repeated games with imperfect information. The central messa
 ge will be that effective synthesis hinges on identifying the right suppor
 t for game equivalence: although the process may face unboundedly branchin
 g information trees\, many different information histories are strategical
 ly indistinguishable. By quotienting these histories via an equivalence th
 at preserves winning strategies (and ω-regular objectives)\, we can repla
 ce the unmanageable information growth by a finite\, strategy-faithful gam
 e abstraction. \nThe talk is based on joint work with Laurent Doyen and T
 homas Soullard presented at FSTTCS 2025.\nShort Bio: Dietmar Berwanger is 
 a CNRS researcher at Laboratoire Méthodes Formelles in Paris-Saclay. He o
 btained his PhD in 2005 from RWTH Aachen University\, and his work sits at
  the intersection of logic\, automata theory\, and infinite games\, with a
 pplications to formal methods. In recent years\, he focused on strategic c
 oordination in games and distributed systems\, in particular on distribute
 d information. Strongly attached to India and its research community\, he 
 will be joining the Indo–French joint research laboratory ReLax in Chenn
 ai for the coming five years.\n
URL:https://www.tcs.tifr.res.in/web/events/1668
DTSTART;TZID=Asia/Kolkata:20260128T160000
DTEND;TZID=Asia/Kolkata:20260128T170000
LOCATION:HBA Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1678
DTSTAMP:20260130T080457Z
SUMMARY:Efficient Algorithmic Decoding of Algebraic and Expander Codes
DESCRIPTION:Speaker: Ashutosh Shankar (TIFR)\n\nAbstract: \nAlgorithmic dec
 oding is the problem of efficiently decoding a corrupted received word\, t
 o obtain the closest codeword or a list of all nearby codewords. An error-
 correcting code\, however theoretically good\, is only of practical use if
  it has _efficient_ decoding algorithms. In this talk I will describe effi
 cient decoding algorithms for several algebraic codes and expander codes.M
 ultivariate Multiplicity codes are a generalisation of Reed-Muller codes\,
  where along with evaluations of a multivariate polynomial\, evaluations o
 f its partial derivatives are also given\, up to some order. The main resu
 lt of this portion is a general algorithm to unique-decode this code for _
 all_ choices of field\, dimension and multiplicity parameter. Hence\, it i
 s also an algorithmic proof of the Multiplicity Schwartz-Zippel lemma.Univ
 ariate Multiplicity codes are an extension of Reed-Solomon codes where eva
 luations of a univariate polynomial along with its derivatives are given. 
 The main result of this section is a way to make the Guruswami-Wang list d
 ecoding algorithm run in nearly linear time. For this\, we have to speed u
 p both steps of Guruswami-Wang: constructing the differential equation and
  solving it. We also generalise our fast list-decoding algorithm to the ca
 se of list recovery.Local testing is the problem of querying a few locatio
 ns to distinguish whether a received word is a codeword or _far_ from all 
 codewords. Many known local tests (the low-degree tests of Friedl-Sudan an
 d Raz-Safra\, for instance) have the property that they work for the inter
 leaved version of their codes as well. This can be seen by looking into th
 eir proofs. We show that this is in fact a general property of locally tes
 table codes\, if the underlying test graph is a good expander. On the way\
 , we also give a stronger definition of local testability that may be of i
 ndependent interest.Finally\, we give a simple algorithm to decode Sipser-
 Spielman expander codes\, that approaches closer to the unique-decoding bo
 und than Sipser and Spielman's original algorithm.\n
URL:https://www.tcs.tifr.res.in/web/events/1678
DTSTART;TZID=Asia/Kolkata:20260202T143000
DTEND;TZID=Asia/Kolkata:20260202T153000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1680
DTSTAMP:20260202T112128Z
SUMMARY:to be announced
DESCRIPTION:Speaker: Neha Sangwan (Halıcıoğlu Data Science Institute\, U
 CSD)\n\nAbstract: \nTo be announced\n
URL:https://www.tcs.tifr.res.in/web/events/1680
DTSTART;TZID=Asia/Kolkata:20260202T160000
DTEND;TZID=Asia/Kolkata:20260202T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1650
DTSTAMP:20260128T041645Z
SUMMARY:Quantified CDCL and Dependency Schemes: A proof-theoretic study
DESCRIPTION:Speaker: Meena Mahajan (Institute of Mathematical Sciences (I.M
 .Sc.))\n\nAbstract: \nIn Quantified Boolean Formulas (QBFs)\, dependency s
 chemes help identify spurious or superfluous variable dependencies introdu
 ced by the quantifier prefix but not essential for constructing countermod
 els. Detecting such dependencies can provably shorten refutations in certa
 in proof systems and is expected to improve the performance of QBF solvers
 . Among the most prominent solving techniques for QBFs is Quantified Confl
 ict-Driven Clause Learning\, a generalization of CDCL to the quantified se
 tting. The QCDCL proof system provides an abstract framework that captures
  the reasoning employed by such solvers.  In this talk\, I will describe 
 how dependency schemes can be incorporated into QCDCL-based proof systems 
 in various phases: during preprocessing\, in the decision heuristics\, or 
 within propagation and learning.\nBased on joint work with Abhimanyu Choud
 hury.\nShort Bio: Meena Mahajan is a professor at The Institute of Mathema
 tical Sciences\, HBNI\, Chennai\, India. Her interests span several sub-a
 reas within theoretical computer science. Her research focusses primarily
  on understanding the limits of efficient computation\, and encompasses m
 any aspects of complexity theory\, including Boolean function complexity\
 , algebraic circuits\, and proof complexity. https://www.imsc.res.in/~mee
 na\n
URL:https://www.tcs.tifr.res.in/web/events/1650
DTSTART;TZID=Asia/Kolkata:20260203T160000
DTEND;TZID=Asia/Kolkata:20260203T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1681
DTSTAMP:20260204T101430Z
SUMMARY:Fundamental Limits of High-Dimensional Inference under Constrained 
 Observations
DESCRIPTION:Speaker: Neha Sangwan (Halıcıoğlu Data Science Institute\, U
 CSD)\n\nAbstract: \nI will discuss recent work on high-dimensional inferen
 ce from nonlinear and quantized observations\, focusing on generalized lin
 ear measurement models. I will describe information-theoretic limits on re
 covery and simple algorithms that approach these limits under structural a
 ssumptions such as sparsity. I will also discuss extensions to models with
  latent structure\, including mixtures of generalized linear models and qu
 antitative group testing\, highlighting how aggregation and heterogeneity 
 reshape fundamental trade-offs in sample complexity and identifiability.\n
 Short Bio: Neha Sangwan is currently a visiting researcher at the Tata Ins
 titute of Fundamental Research (TIFR) and previously held a postdoctoral p
 osition at the University of California San Diego. She received her PhD fr
 om TIFR\, and her research focuses on information-theoretic foundations of
  high-dimensional inference\, sequential decision-making in quantum system
 s\, and reliable communication under adversarial uncertainty.\n
URL:https://www.tcs.tifr.res.in/web/events/1681
DTSTART;TZID=Asia/Kolkata:20260204T160000
DTEND;TZID=Asia/Kolkata:20260204T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1685
DTSTAMP:20260205T113347Z
SUMMARY:Gödel's gift to Cryptography: Zero-Knowledge Proofs without Intera
 ction and with Perfect Soundness
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nZero-Knowledge 
 proofs are a staple of cryptography\, discovered in a seminal work of Gold
 wasser\, Micali and Rackoff. They are protocols that allow a prover to con
 vince a verifier that a statement is true\, essentially without revealing 
 any information about why the statement is true. But unlike traditional pr
 oofs\, they require interaction between the prover and verifier\, and ther
 e is always some non-zero probability of the verifier getting convinced of
  an incorrect statement (imperfect soundness). Known impossibility results
  show that these drawbacks are unavoidable. Traditional zero-knowledge pro
 ofs use cryptographic assumptions such as the existence of one-way functio
 ns. In this (hopefully not zero-knowledge) talk\, we will see a glimpse of
  how proof complexity -- using the conjectured absence of optimal proof sy
 stems (along the lines of Gödel's incompleteness theorem) -- helps us ach
 ieve a relaxation of zero-knowledge proofs with no interaction\, no "setup
 " (a milder form of interaction)\, and with perfect soundness.\nLink to th
 e paper: https://eprint.iacr.org/2025/1296.pdf\n
URL:https://www.tcs.tifr.res.in/web/events/1685
DTSTART;TZID=Asia/Kolkata:20260206T160000
DTEND;TZID=Asia/Kolkata:20260206T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1664
DTSTAMP:20260209T062332Z
SUMMARY:Finding an Element of High Order Modulo a Composite
DESCRIPTION:Speaker: Ben Lee Volk (Reichman University)\n\nAbstract: \nWe w
 ill discuss a deterministic algorithm that\, given a composite number N an
 d a target order D ≥ N^{1/6}\, runs in time D^{1/2+o(1)} and finds eithe
 r an element of multiplicative order at least D\, or a nontrivial factor o
 f N. Our algorithm improves upon an algorithm of Hittmeir (2018)\, who gav
 e an algorithm with similar guarantees under stronger assumptions. Hittmei
 r's algorithm played a crucial role in the recent breakthrough determinist
 ic integer factorization algorithms of Hittmeir and Harvey (2020\, 2021).B
 ased on a joint work with Ziv Oznovich.\n \nShort Bio: Ben Lee Volk is a 
 member of the faculty at the School of Computer Science at Reichman Univer
 sity in Israel. He did his PhD at Tel Aviv University and spent his postdo
 c years at Caltech and UT Austin before moving to Reichman. His research i
 nterests are broadly in computational complexity\, with a particular focus
  on algebraic complexity\, algorithms for algebraic problems\, error corre
 cting codes and pseudorandomness.\n
URL:https://www.tcs.tifr.res.in/web/events/1664
DTSTART;TZID=Asia/Kolkata:20260210T160000
DTEND;TZID=Asia/Kolkata:20260210T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1677
DTSTAMP:20260209T062627Z
SUMMARY:What Kinds of Functions Do Neural Networks Learn? Low-Norm vs. Flat
  Solutions
DESCRIPTION:Speaker: Rahul Parhi (University of California\, San Diego (UCS
 D))\n\nAbstract: \nThis talk investigates the fundamental differences betw
 een low-norm and flat solutions of shallow ReLU networks training problems
 \, particularly in high-dimensional settings. We sharply characterize the 
 regularity of the functions learned by neural networks in these two regime
 s. This enables us to show that global minima with small weight norms exhi
 bit strong generalization guarantees that are dimension-independent. In co
 ntrast\, local minima that are "flat" can generalize poorly as the input d
 imension increases. We attribute this gap to a phenomenon we call neural s
 hattering\, where neurons specialize to extremely sparse input regions\, r
 esulting in activations that are nearly disjoint across data points. This 
 forces the network to rely on large weight magnitudes\, leading to poor ge
 neralization. Our analysis establishes an exponential separation between f
 lat and low-norm minima. In particular\, while flatness does imply some de
 gree of generalization\, we show that the corresponding convergence rates 
 necessarily deteriorate exponentially with input dimension. These findings
  suggest that flatness alone does not fully explain the generalization per
 formance of neural networks.\n \nShort Bio: Rahul Parhi is an Assistant P
 rofessor at the University of California\, San Diego. Prior to joining UCS
 D\, he was a Postdoctoral Researcher at the École Polytechnique Fédéral
 e de Lausanne (EPFL)\, where he worked from 2022 to 2024. He completed his
  PhD at the University of Wisconsin-Madison in 2022. His research is focus
 ed on the mathematical foundations of neural networks\, and its connection
 s with functional/harmonic analysis\, approximation theory\, and statistic
 s.\n
URL:https://www.tcs.tifr.res.in/web/events/1677
DTSTART;TZID=Asia/Kolkata:20260211T150000
DTEND;TZID=Asia/Kolkata:20260211T160000
LOCATION:HBA Foyer
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1687
DTSTAMP:20260210T084434Z
SUMMARY:Sparsifying Sums of Positive Semidefinite Matrices
DESCRIPTION:Speaker: Pravesh K. Kothari (Princeton University)\n\nAbstract:
  \nI will talk about a new instance-specific sparsification theorem for su
 ms of PSD matrices. As a corollary\, I will show that every Cayley graph o
 n any group has a weighted Cayley sparsifier with O(\\log^4 |G|) generator
 s. \nBased on joint work with Arpon Basu (Princeton)\, Yang Liu (CMU)\, a
 nd Raghu Meka (UCLA). \n \n \nShort Bio: Pravesh K Kothari received hi
 s Ph. D. from the University of Texas at Austin in 2016 after a Bachelor's
  degree from Indian Institute of Technology\, Kanpur. He is currently an A
 ssistant Professor in the Computer Science Department at Princeton Univers
 ity. Earlier\, from 2019-2023\, he was an Assistant Professor in the Compu
 ter Science Department at Carnegie Mellon University. Dr. Kothari was a Re
 search Instructor of Computer Science jointly hosted by the Institute for 
 Advanced Study\, Princeton and the Department of Computer Science at Princ
 eton University from 2016-19.Dr. Kothari's research interests span several
  topics in theoretical computer science such as convex optimization and ap
 plications to algorithm design\, algorithms and lower bounds for statistic
 al estimation and average-case combinatorial optimization\, and spectral m
 ethods and connections to random matrix theory\, coding theory and extrema
 l combinatorics.Dr Kothari is a recipient of the Presburger Award (2024)\,
  IIT Kanpur Young Alumnus Award (2023)\, Sloan Fellowship (2022)\, NSF Car
 eer Award (2021)\, and Simons Award for Graduate students in Theoretical C
 omputer Science (2014).\n
URL:https://www.tcs.tifr.res.in/web/events/1687
DTSTART;TZID=Asia/Kolkata:20260213T113000
DTEND;TZID=Asia/Kolkata:20260213T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1691
DTSTAMP:20260213T080543Z
SUMMARY:Existence and Computation of EFX Allocations with Charity
DESCRIPTION:Speaker: Vivek Karunakaran (TIFR)\n\nAbstract: \nThe fair divis
 ion of indivisible goods is a central problem in social choice theory\, wi
 th Envy-Freeness up to any Good (EFX) serving as a critical relaxation of 
 envy-freeness. While the existence of Envy-Free up to one Good (EF1) is we
 ll-established\, the existence of EFX allocations for more than three agen
 ts remains a significant open problem. This difficulty motivates the study
  of EFX with charity\, a relaxation where a subset of items remains unallo
 cated to ensure the remaining distribution satisfies the EFX property. Thi
 s talk focuses on the definition of EFX with charity and the constructive 
 proof of its existence for general monotone valuations. We specifically pr
 esent a pseudo-polynomial time algorithm that computes an allocation where
  no agent envies the unallocated pool and the number of unallocated items 
 is strictly bounded by $n-1$.\n
URL:https://www.tcs.tifr.res.in/web/events/1691
DTSTART;TZID=Asia/Kolkata:20260213T160000
DTEND;TZID=Asia/Kolkata:20260213T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1688
DTSTAMP:20260210T043603Z
SUMMARY:EFX Allocations for Three and More Types of Agents.
DESCRIPTION:Speaker: Vishwa Prakash (Chennai Mathematical Institute)\n\nAbs
 tract: \nGiven a set of indivisible goods that are to be allocated among a
 gents with differing preferences\, EFX fairness requires that no agent pre
 fers any strict subset of another agent's bundle. Do such allocations alwa
 ys exist? This question has emerged as one of the most challenging open pr
 oblems in discrete fair division.\nDue to the difficulty of this problem\,
  several restricted and relaxed variants have been studied. EFX allocation
 s are known to exist in structured settings\, such as for three agents\, a
 nd under relaxations including multiplicative approximations\, most notabl
 y that a 0.618-EFX allocation always exists. Another prominent relaxation 
 is EFX with charity\, which seeks a large partial EFX allocation while lea
 ving a small number of goods unallocated.\nIn this talk\, I will present n
 ew results on the existence of EFX and approximate EFX when agents can be 
 partitioned into a small number of types\, with agents of the same type ha
 ving identical valuations. We show that EFX allocations exist for three ty
 pes of agents\, and that a 2/3-EFX allocation exists for four types. Addit
 ionally\, we strengthen guarantees for EFX with charity by establishing bo
 unds that depend explicitly on the number of distinct agent types.\nThe re
 sults presented in this talk are drawn from three papers (Paper1\, Paper2
 \, Paper3)\, coauthored with Pratik Ghosal\, Ruta Mehta\, Prajakta Nimbho
 rkar\, and Nithin Varma. \n \nShort Bio: Vishwa Prakash is a PhD student
  at the Chennai Mathematical Institute\, working under the supervision of 
 Prof. Prajakta Nimbhorkar. He works on Discrete Fair Division\, and more b
 roadly on Algorithmic Game Theory. \n
URL:https://www.tcs.tifr.res.in/web/events/1688
DTSTART;TZID=Asia/Kolkata:20260216T140000
DTEND;TZID=Asia/Kolkata:20260216T150000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1684
DTSTAMP:20260210T084518Z
SUMMARY:Efficient PCPs from High-Dimensional Expanders
DESCRIPTION:Speaker: Mitali Bafna (University of Washington)\n\nAbstract: \
 nThe theory of probabilistically checkable proofs (PCPs) shows how to enco
 de a proof for any theorem into a format where the theorem's correctness c
 an be verified by making only a constant number of queries to the proof. T
 he PCP Theorem [ALMSS] is a fundamental result in computer science with fa
 r-reaching consequences in hardness of approximation\, cryptography\, and 
 blockchain technology. A PCP has two important parameters: 1) the size of 
 the encoding\, and 2) soundness\, which is the probability that the verifi
 er accepts an incorrect proof\, both of which we wish to minimize.\nIn 200
 5\, Dinur gave a surprisingly elementary and purely combinatorial proof of
  the PCP theorem that relies only on tools such as graph expansion\, while
  also giving the first construction of 2-query PCPs with quasi-linear size
  and constant soundness (close to 1). Our work improves upon Dinur's PCP a
 nd constructs 2-query\, quasi-linear size PCPs with arbitrarily small cons
 tant soundness\, using high-dimensional expanders (HDX). As a direct conse
 quence\, assuming the exponential time hypothesis\, we get that no approxi
 mation algorithm for 3-SAT can achieve an approximation ratio significantl
 y better than 7/8 in time 2^{n/polylog n}.\nIn this talk\, I will discuss 
 the main components of our PCP\, without assuming any familiarity with PCP
 s or HDX. This is based on joint works with Noam Lifshitz\, Dor Minzer\, N
 ikhil Vyas and Zhiwei Yun.\n \nShort Bio: \nMitali Bafna is a theoretica
 l computer scientist and an Assistant Professor in the Allen School of Com
 puter Science & Engineering at the University of Washington. Her research 
 explores complexity theory and algorithms\, particularly approximation alg
 orithms\, probabilistically checkable proofs\, and high-dimensional expand
 ers. \nShe received her undergraduate degree from IIT Madras and her Ph.D
 . in Computer Science from Harvard University in 2022\, advised by Prof. M
 adhu Sudan. After that\, she was a postdoc at CMU\, hosted by Professors A
 ayush Jain and Pravesh Kothari\, followed by a postdoc in the MIT Departme
 nt of Mathematics.\n \n \n
URL:https://www.tcs.tifr.res.in/web/events/1684
DTSTART;TZID=Asia/Kolkata:20260220T113000
DTEND;TZID=Asia/Kolkata:20260220T123000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1689
DTSTAMP:20260216T045736Z
SUMMARY:Proving "Undirected Connectivity in Logspace" in Logspace
DESCRIPTION:Speaker: Sasank Mouli (IIT Indore)\n\nAbstract: \nReingold (STO
 C '05) proved in his breakthrough result that the problem of Undirected Co
 nnectivity\, i.e. deciding whether nodes s and t are connected in a gi
 ven undirected graph G\, is in Logspace\, culminating incremental improve
 ments over a long series of works. In this talk\, we will discuss whether 
 Logspace can define and prove all the concepts involved in this result. Na
 mely\, is there a proof of "Undirected Connectivity in Logspace" in a syst
 em of Bounded Arithmetic that can only reason with concepts definable in L
 ogspace? We answer this question in the affirmative. To establish this res
 ult\, we use an alternative and arguably simpler proof of this result\, by
  Rozenman and Vadhan (APPROX-RANDOM '05). Additionally\, both proofs use e
 igenvalues and eigenvectors which are not known to be definable in Logspac
 e\, so we use the alternate and essentially equivalent concept of mixing r
 atios to formalize Rozenman and Vadhan's proof\, using results from Buss\,
  Kabanets\, Kolokolova\, Koucky (Ann. Pure and Applied Logic\, 2020) and M
 ihail (FOCS '89) to bridge the gap. The proof is then completed by applyin
 g fixes to other concepts outside of Logspace used in the proof such as sq
 uare roots and iterated matrix multiplication. Based on joint work with Sa
 m Buss\, Anant Dhayal\, Valentine Kabanets and Antonina Kolokolova. \nSho
 rt Bio: Sasank Mouli is an Assistant Professor at the Indian Institute of 
 Technology\, Indore. He received his PhD from the University of California
 \, San Diego and his Bachelors degree from the Indian Institute of Technol
 ogy\, Kanpur. His area of research is Proof Complexity. \n
URL:https://www.tcs.tifr.res.in/web/events/1689
DTSTART;TZID=Asia/Kolkata:20260220T160000
DTEND;TZID=Asia/Kolkata:20260220T170000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1670
DTSTAMP:20260219T110701Z
SUMMARY:Cryptographic proofs for privacy and integrity
DESCRIPTION:Speaker: Chaya Ganesh (Indian Institute of Science (IISc)\, Ben
 galuru)\n\nAbstract: \nIn this talk\, we will show how one can verify th
 e correctness of a computation much more efficiently than having to re-per
 form the computation. We will introduce the notion of succinct non-inter
 active argument systems (SNARK) that allow a prover to convince a verifie
 r about the correctness of computation such that verification is exponenti
 ally faster than the computation itself\, and zero-knowledge\, where the
  verifier learns nothing beyond the truth of the statement. We will outlin
 e the design principle underlying SNARK constructions that use a cryptogra
 phic compiler on an information-theoretic proof system.  Many popular SNA
 RKs use Polynomial Interactive Oracle Proofs (PIOPs) as the information-th
 eoretic component\, and then compile the PIOP into a succinct argument sys
 tem using a cryptographic tool called a Polynomial Commitment Scheme (PCS)
 .We then provide a framework for transforming a univariate polynomial comm
 itment scheme into a multilinear polynomial commitment scheme. The transfo
 rmation is generic\, can be instantiated with any univariate scheme and im
 proves on prior transformations in all relevant parameters: proof size\, v
 erification complexity\, and prover complexity.\nShort Bio: Chaya Ganesh i
 s an Associate Professor in the Department of Computer Science and Autom
 ation at Indian Institute of Science . Before joining IISc\, she was a 
 post-doctoral researcher in Aarhus University\, and prior to that she rece
 ived her PhD from NYU's Courant Institute of Mathematical Sciences.Her r
 esearch interests are broadly in Cryptography and Security. She has won th
 e IBM global university award\, Google and Protocol labs research grants\
 , Infosys Young investigator award and Intel Rising Star Faculty award.\n
  \n
URL:https://www.tcs.tifr.res.in/web/events/1670
DTSTART;TZID=Asia/Kolkata:20260224T160000
DTEND;TZID=Asia/Kolkata:20260224T170000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1693
DTSTAMP:20260223T044735Z
SUMMARY:Novel quantum coding schemes to advance quantum communications
DESCRIPTION:Speaker: Paolo Villoresi (Full professor of Physics\,  Universi
 ty of Padova)\n\nAbstract: \nQuantum communications represent the most fun
 damental level of physical exchange between distant interlocutors. At the
  heart of these there is the encoding of the quantum state\, that use one 
 or mode degrees of freedom of the electromagnetic field or\, in the corpus
 cular view\, the single photons. In this talk\, advances will be presente
 d both on the type of degrees of freedom and on the type of encoding\, whi
 ch allow to achieve advanced quantum communications both from the point of
  view of tests on the foundations of quantum physics and on the applicatio
 ns.\n Peri\, A. et al. High-performance heterodyne receiver for quantum i
 nformation processing in a laser-written integrated photonic platform. Adv
 . Photonics 8\, 1–16 (2026).\nVinet\, S. et al. npj Quantum Information 
 Article in Press Time-resolved certification of frequency-bin entanglement
  over multi-mode channels T. to appear\, npj Quantum Inf (2026).\nMohageg\
 , M. et al. Towards satellite tests combining general relativity and quant
 um mechanics through quantum optical interferometry: progress on the deep 
 space quantum link. EPJ Quantum Technol. 12\, 78 (2025).\nLopes Da Costa\,
  B. et al. Power-consumption back door in quantum key distribution. Phys. 
 Rev. Appl. 24\, 1 (2025).\nVijayadharan\, K. et al. A Sagnac-based arbitra
 ry time-bin state encoder for quantum communication applications. EPJ Quan
 tum Technol. 12\, (2025).\nShort Bio: Prof. Paolo Villoresi is Full Profes
 sor of Experimental Physics at the University of Padua and Director of the
  Padua Quantum Technologies Research Center. He is a pioneer in space-base
 d quantum communications\, leading the first demonstration of single-photo
 n exchange between space and Earth and subsequent landmark experiments in 
 satellite quantum communication. Founder of the QuantumFuture research gro
 up\, his work spans quantum optics\, secure communications\, and quantum i
 nformation protocols. He has authored over 300 scientific publications and
  holds multiple industrial patents in quantum technologies.\n \n
URL:https://www.tcs.tifr.res.in/web/events/1693
DTSTART;TZID=Asia/Kolkata:20260224T170000
DTEND;TZID=Asia/Kolkata:20260224T180000
LOCATION:AG-66
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1686
DTSTAMP:20260225T044418Z
SUMMARY:On Propositional Reasoning with Parities
DESCRIPTION:Speaker: Dmitry Itsykson (Ben-Gurion University of the Negev)\n
 \nAbstract: \nIn the talk\, we consider the propositional proof system Res
 olution over Parities (Res(⊕))\, in which the unsatisfiability of a Bool
 ean formula is established by analyzing the parity of sums of variables\, 
 that is\, through case analysis. This proof system extends classical Resol
 ution by allowing reasoning modulo 2\, thereby providing a more expressive
  framework for capturing parity-based inference. Understanding the strengt
 hs and limitations of Res(⊕) is an important step toward clarifying the 
 role of parity in propositional proofs and SAT solving.A central open prob
 lem is to construct formulas that do not admit short (polynomial-size) ref
 utations in this system. For many years\, such hard instances were known o
 nly for the tree-like version of Res(⊕)\, which forbids the simultaneous
  analysis of multiple cases.In this talk\, I will provide an overview of r
 ecent progress beyond tree-like restrictions\, establishing exponential lo
 wer bounds for bounded-depth Res(⊕)\, where the depth grows superlinearl
 y. I will also highlight the main lower-bound techniques\, including rando
 m walks with restarts and lifting with stifling gadgets. No prior backgro
 und in proof complexity will be assumed.\nShort Bio: Dmitry Itsykson is a 
 non-faculty researcher at Ben-Gurion University of the Negev (BGU). He rec
 eived his PhD from St. Petersburg State University in 2009 and his Habilit
 ation in 2022 from the St. Petersburg Department of Steklov Mathematical I
 nstitute of the Russian Academy of Sciences (PDMI). He has been a member o
 f PDMI since 2009\, where he holds the rank of Leading Researcher\, and ha
 s been on leave since joining BGU in 2022.He held part-time Associate Prof
 essor positions at St. Petersburg Academic University (2010–2019) and St
 . Petersburg State University (2018–2022). His research interests are in
  computational complexity theory\, with a focus on propositional proof com
 plexity\, average-case complexity\, and lower bounds for Boolean satisfiab
 ility (SAT) algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1686
DTSTART;TZID=Asia/Kolkata:20260225T160000
DTEND;TZID=Asia/Kolkata:20260225T170000
LOCATION:A -201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1696
DTSTAMP:20260225T060548Z
SUMMARY:List Decoding in Coding Theory: Algebra\, Expanders and Algorithms
DESCRIPTION:Speaker: Shashank Srivastava (Institute for Advanced Study (IAS
 ) and DIMACS)\n\nAbstract: \nThe goal of error correcting codes is to enco
 de data in a way that allows for this data to be recovered even if the enc
 oded copy is corrupted by an adversary. The usual algorithmic challenge a
 ssociated with codes\, called decoding\, is to output the uncorrupted copy
  of data by looking only at the corrupted copy. However\, when noise level
 s are high\, the same corrupted copy could correspond to multiple uncorrup
 ted copies. The task of list decoding is to output all such candidates. I
 n this talk\, we will talk about what makes list decoding interesting and 
 challenging\, and its somewhat surprising connections to other areas in CS
 . We will then survey recent progress in list decoding for codes based on 
 algebra and on expander graphs. \nShort Bio: Shashank Srivastava is a jo
 int postdoc between Institute for Advanced Study (IAS) and DIMACS\, Rutger
 s University. Before this\, he obtained a PhD in 2024 from TTI Chicago and
  a BTech in 2018 from IIT Kharagpur. Shashank's research focuses on coding
  theory and spectral algorithms\, and his work has won Best Paper and Best
  Student Paper awards at SODA.\n
URL:https://www.tcs.tifr.res.in/web/events/1696
DTSTART;TZID=Asia/Kolkata:20260226T090000
DTEND;TZID=Asia/Kolkata:20260226T100000
LOCATION:via Zoom in A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1692
DTSTAMP:20260218T043348Z
SUMMARY:Window Mean Payoff in Turn-Based Stochastic Games
DESCRIPTION:Speaker: Pranshu Gaba (TIFR)\n\nAbstract: \nWe look at turn-bas
 ed stochastic games\, which are two-player zero-sum games played on direct
 ed graphs in which each edge has a payoff associated with it and each vert
 ex is either controlled by Player 1 or by Player 2\, or is a probabilistic
  vertex. The game begins by placing a token on an initial vertex. Then\, w
 henever the token is on a player-controlled vertex\, that player chooses a
 n out-edge and whenever the token is on a probabilistic vertex\, an out-ed
 ge is chosen according to the underlying distribution\, and in both cases\
 , the token moves along the chosen edge. The play goes on in this manner f
 orever\, resulting in an infinite path in the graph\, which in turn gives 
 an infinite sequence of payoffs for Player 1. Fixing strategies of both pl
 ayers gives a distribution over plays in the graph. A well-studied object
 ive in stochastic games is the mean-payoff objective\, which requires that
  the average payoff per turn in the limit of the play be non-negative. In 
 this thesis\, we study a finitary version of the mean-payoff objective cal
 led the window mean-payoff objective. The window mean-payoff objective str
 engthens the mean-payoff objective by requiring that the average payoff be
 come non-negative in every sliding window (of bounded length) of the play.
  In particular\, we see algorithms for the following decision problems:- S
 atisfaction: Does Player 1 have a strategy to ensure\, with probability at
  least p\, that the window mean-payoff value of the play is non-negative?-
  Expectation: Does Player 1 have a strategy to ensure that the window mean
 -payoff value of the play is non-negative in expectation?- Optimizing expe
 ctation with guarantees: Does Player 1 have a strategy to simultaneously e
 nsure that the window mean-payoff value of the play is non-negative surely
  (or almost-surely or limit-surely) and is greater than a given threshold 
 in expectation?- Sure-almost-sure satisfaction (in Markov Decision Process
 es (MDPs)): Does Player 1 have a strategy to simultaneously ensure that th
 e window mean-payoff value of the play is non-negative surely and is great
 er than a given threshold almost-surely? (MDPs are a special case of stoch
 astic games with no Player 2 controlled vertices.)Moreover\, whenever a wi
 nning strategy exists for a player\, we show how to construct the strategy
  and also give bounds on the amount of memory required to define the strat
 egy.\n
URL:https://www.tcs.tifr.res.in/web/events/1692
DTSTART;TZID=Asia/Kolkata:20260226T174500
DTEND;TZID=Asia/Kolkata:20260226T184500
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1694
DTSTAMP:20260225T100549Z
SUMMARY:The communication complexity of distributed estimation
DESCRIPTION:Speaker: Parikshit Gopalan (Apple)\n\nAbstract: \nWe propose an
  extension of Yao's standard two-party communication model\, where Alice a
 nd Bob respectively hold probability distributions p and q over inputs to 
 a function f\, rather than singleton inputs. Their goal is to estimate E[f
 (x\,y)] to within additive error eps where x is drawn from p and y is draw
 n (independently) from q. We refer to this as the distributed estimation p
 roblem for f. We motivate this problem by showing that communication probl
 ems studied in sketching\, databases and learning are instantiations of di
 stributed estimation for various functions f. Our goal is to understand ho
 w the communication scales with the complexity of f and the error paramete
 r eps. \nThe naive sampling protocol achieves communication that scales a
 s O(1/eps^2). We design a new debiasing protocol for arbitrary bounded fun
 ctions that requires communication only linear in 1/\\eps\, and gives bett
 er variance reduction than random sampling. We develop a novel spectral te
 chnique to show lower bounds for distributed estimation\, and use it to sh
 ow that the Equality function is the easiest full rank Boolean function fo
 r distributed estimation. This technique yields tight lower bounds for mos
 t functions\, with set-disjointness being the notable exception. Based on 
 joint work with Raghu Meka (UCLA)\, Prasad Raghavendra (UC Berkeley)\, Mih
 ir Singhal (UC Berkeley) and Avi Wigderson (IAS). \n \nShort Bio: I am a
  machine learning researcher at Apple where I work on the foundations of 
 machine learning. I aspire to do fundamental theoretical research that imp
 acts practical problems. My current focus is on the interplay between mult
 igroup fairness\, loss minimization and indistinguishability. I am also in
 terested in questions related to calibration\, distribution drift and anom
 aly detection.I have broad interests in theoretical computer science\, hav
 ing worked on coding and information theory\, pseudorandomness and computa
 tional complexity. On the applied side\, I have worked on systems for stor
 ing and interactively visualizing large datasets.In the past\, I have been
  a researcher at VMware Research\, Microsoft Research in Redmond and Si
 licon Valley\, a graduate student at Georgia Tech and an undergraduate a
 t IIT Bombay\n
URL:https://www.tcs.tifr.res.in/web/events/1694
DTSTART;TZID=Asia/Kolkata:20260227T140000
DTEND;TZID=Asia/Kolkata:20260227T150000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1699
DTSTAMP:20260227T051101Z
SUMMARY:Training a 3-node neural network is NP-complete
DESCRIPTION:Speaker: Nishant Das (TIFR)\n\nAbstract: \nIn this work\, the a
 uthors consider a 2-layer\, 3-node\, n-input neural network whose nodes co
 mpute linear threshold functions of their inputs. They show that it is NP-
 complete to decide whether there exist weights and thresholds for this net
 work so that it produces output consistent with a given set of training ex
 amples. They also extend the result to other simple networks. Furthermore\
 , they also present a network for which training is hard but where switchi
 ng to a more powerful representation makes training easier. These results 
 suggest the importance\, given a training problem\, of finding an appropri
 ate network and input encoding for that problem.\n
URL:https://www.tcs.tifr.res.in/web/events/1699
DTSTART;TZID=Asia/Kolkata:20260227T160000
DTEND;TZID=Asia/Kolkata:20260227T170000
LOCATION:A-206
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1697
DTSTAMP:20260227T042429Z
SUMMARY:Nash Regret and Beyond: Optimal Fairness Guarantees in Bandit Probl
 ems
DESCRIPTION:Speaker: Sayak Ray Chowdhury (IIT Kanpur)\n\nAbstract: \nTradit
 ional regret minimization in multi-armed bandits focuses on maximizing cum
 ulative reward\, often overlooking fairness across individuals receiving o
 utcomes. Motivated by applications such as clinical trials and resource al
 location\, Nash regret has been proposed as a fairness-aware metric based 
 on the geometric mean of rewards. In this talk\, I will present recent res
 ults showing that near-optimal Nash regret can be achieved using simple an
 d general bandit algorithms under mild assumptions in stochastic bandits\,
  along with extensions to a broader class of power-mean fairness objective
 s. I will then discuss fairness in linear bandits\, where we obtain the fi
 rst order-optimal Nash regret bounds in dimension and introduce a generic 
 meta-algorithm that converts standard linear bandit methods into fairness-
 aware versions with provable guarantees. Empirical results demonstrate con
 sistent improvements over existing approaches. Overall\, the work highligh
 ts that fairness can be incorporated into bandit learning without sacrific
 ing statistical efficiency.\nShort Bio: Sayak Ray Chowdhury is an Assista
 nt Professor in the Department of Computer Science and Engineering at the 
 Indian Institute of Technology Kanpur. His research focuses on sequential 
 decision making under uncertainty\, including multi-armed bandits\, reinfo
 rcement learning\, and language model alignment\, as well as on privacy an
 d fairness in ML. Prior to joining IIT Kanpur\, he was a Postdoctoral Rese
 archer at Microsoft Research India and Boston University. He received his 
 Ph.D. from the Indian Institute of Science (IISc) Bangalore. He is a recip
 ient of the INAE Young Associate award from the Indian National Academy of
  Engineering.\n
URL:https://www.tcs.tifr.res.in/web/events/1697
DTSTART;TZID=Asia/Kolkata:20260304T160000
DTEND;TZID=Asia/Kolkata:20260304T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1698
DTSTAMP:20260302T043549Z
SUMMARY:The coding theoretic limits of robust watermarking for generative m
 odels
DESCRIPTION:Speaker: Shubham Pawar (Royal Holloway\, University of London)\
 n\nAbstract: \nWe ask a basic question about cryptographic watermarking fo
 r generative models: to what extent can a watermark remain reliable when a
 n adversary is allowed to corrupt the encoded signal? To study this quest
 ion\, we introduce a minimal coding abstraction thatwe call a zero-bit tam
 per-detection code. This is a secret-key procedure that samples a pseudor
 andom codeword and\, given a candidate word\, decides whether it should be
  treated as unmarked content or as the result of tampering with a valid c
 odeword. It captures the two core requirements of robust watermarking: so
 undness and tamper detection. Within this abstraction we prove a sharp un
 conditional limit on robustness to independent symbol corruption. For an a
 lphabet of size q\, there is a critical corruption rate of 1 − 1/q such
  that no scheme with soundness\, even relaxed to allow a fixed constant fa
 lse positive probability on random content\, can reliably detect tamperin
 g once an adversary can change more than this fraction of symbols. In par
 ticular\, in the binary case no cryptographic watermark can remain robust
  if more than half of the encoded bits are modified. We also show that th
 is threshold is tight by giving simple information-theoretic constructions
  that achieve soundness and tamper detection for all strictly smaller cor
 ruption rates. We then test experimentally whether this limit appears in 
 practice by looking at the recent watermarking for images of Gunn\, Zhao\
 , and Song (ICLR 2025). We show that asimple crop and resize operation rel
 iably flipped about half of the latent signs and consistently prevented be
 lief-propagation decoding from recovering the codeword\, erasing thewaterm
 ark while leaving the image visually intact.\n \nShort Bio: Shubham Vivek
  Pawar is a PhD student at Royal Holloway\, Universit of London. His resea
 rch interest lie in cryptography\, computational complexity and quantum co
 mputing.\n
URL:https://www.tcs.tifr.res.in/web/events/1698
DTSTART;TZID=Asia/Kolkata:20260306T160000
DTEND;TZID=Asia/Kolkata:20260306T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1683
DTSTAMP:20260227T042839Z
SUMMARY:An Efficient Algorithm for Incremental Metric Bipartite Matching
DESCRIPTION:Speaker: Syamantak Das (Indraprastha Institute of Information T
 echnology Delhi (IIIT-Delhi))\n\nAbstract: \n\nThe minimum-cost bipartite 
 matching problem between two point sets R and S in a metric space has 
 numerous applications in machine learning\, computer vision\, and logistic
 s. For example\, it arises in estimating the 1-Wasserstein distance betwee
 n continuous probability distributions\, as well as in efficiently assigni
 ng taxi requests to customers while minimizing travel cost prior to pickup
 . However\, computing a minimum-cost matching in general metric spaces is 
 computationally demanding. This challenge is particularly acute in dynamic
  settings where points arrive over time and each update would naively requ
 ire recomputing the solution from scratch.In this work\, given a fixed set
  S\, we present a deterministic algorithm that maintains—after i inse
 rtions into R—an O(1/δ⁰·⁶³¹)-approximate minimum-cost matching 
 of cardinality i between R and S in arbitrary metric spaces. The alg
 orithm achieves an amortized insertion time of O(n¹⁺ᵟ) per added poin
 t in R.To the best of our knowledge\, this is the first constant-factor a
 pproximation algorithm for incremental minimum-cost matching that applies 
 to general metric spaces and runs in update time sublinear in the number o
 f edges of the underlying graph (which is n² in a metric space). Prior to
  our work\, a comparable result was known only for constant-dimensional Eu
 clidean spaces (Goranci et al.\, ICML 2025).\nShort Bio:  Syamantak Das i
 s an Assistant Professor at IIIT-Delhi. He received his Ph.D. from IIT Del
 hi and subsequently spent two years in Germany as a postdoc at MPI-Informa
 tik and University of Bremen. He works in the theory of algorithm design w
 ith a  focus on approximation\, online and dynamic algorithms for problem
 s related to graphs and clustering. \n
URL:https://www.tcs.tifr.res.in/web/events/1683
DTSTART;TZID=Asia/Kolkata:20260310T160000
DTEND;TZID=Asia/Kolkata:20260310T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1700
DTSTAMP:20260310T053738Z
SUMMARY:Theoretical Physics for Robust\, Interpretable AI
DESCRIPTION:Speaker: Anindita Maiti (Perimeter Institute)\n\nAbstract: \n\n
 Despite rapid progress in state-of-the-art AI models for theoretical physi
 cs\, most such methods remain black boxes: lacking guarantees of robust an
 d reliable predictions that meet uncertainty quantification benchmarks ess
 ential in scientific domains. To address this gap\, I will present a few d
 irections that improve robustness\, mechanistic interpretability\, and unc
 ertainty quantification of complex learning and sample generation abilitie
 s\, by combining quantum and statistical field theories with computational
  statistics. First\, I will present the simplest model capable of in-conte
 xt learning\, an ability that underpins Large Language Model (LLM) success
 \, particularly for quantum. Leveraging Replica Mean Field Theory and Rand
 om Matrix Theory\, the performance of a simplified LLM is exactly derived 
 in the joint asymptotic limit of a large number of training samples\, toke
 n dimensions\, sample length\, and task diversity: exhibiting a phase tran
 sition in learning abilities. Next\, I will introduce Neural Network Field
  Theory Correspondence\, a paradigm which generates field theory samples w
 ithout any training algorithms\, while guaranteeing low uncertainty bounds
  at scale. This explainable + interpretable alternative to Monte Carlo sam
 pling facilitates a bidirectional mapping between field theory actions and
  their dual Neural Network architectures. Lastly\, I will present a framew
 ork for systematic coarsegraining of data features irrelevant to learning 
 objectives. Building on the Renormalization Group (RG)\, this scheme ensur
 es that perturbations to model predictions caused by such coarsegraining a
 re bound within scientific uncertainty measures\, while capturing nontrivi
 al corrections elusive to the state-of-the-art spectral bias method. Altog
 ether\, these Physics-of-AI approaches advance Scientific AI reliability i
 n a first-principles manner\, while bridging AI with fundamental physics.\
 n \n
URL:https://www.tcs.tifr.res.in/web/events/1700
DTSTART;TZID=Asia/Kolkata:20260311T150000
DTEND;TZID=Asia/Kolkata:20260311T160000
LOCATION:AG-69 and also via Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1701
DTSTAMP:20260312T060149Z
SUMMARY:GM-MDS Conjecture: MDS matrices over small fields
DESCRIPTION:Speaker: Soham Chatterjee (TIFR)\n\nAbstract: \nAn MDS matrix i
 s a matrix whose minors all have full rank. A question arising in coding t
 heory is what zero patterns can MDS matrices have. There is a natural comb
 inatorial characterization (called the MDS condition) which is necessary o
 ver any field\, as well as sufficient over very large fields by a probabil
 istic argument. Dau et al. conjectured that the MDS condition is sufficien
 t over small fields as well\, where the construction of the matrix is alge
 braic instead of probabilistic. This is known as the GM-MDS conjecture. Co
 ncretely\, if a k × n zero pattern satisfies the MDS condition\, then the
 y conjecture that there exists an MDS matrix with this zero pattern over a
 ny field of size |F| ≥ n + k - 1. In this talk\, we will discuss the GM-
 MDS conjecture and a more general version proposed by Shachar Lovett in hi
 s FOCS 2018 paper. We will also try to see this general conjecture in a sp
 ecial case\, which implies the original GM-MDS conjecture as a special cas
 e and will also try to prove the special case.\nLink of paper: https://arx
 iv.org/abs/1803.02523\n
URL:https://www.tcs.tifr.res.in/web/events/1701
DTSTART;TZID=Asia/Kolkata:20260313T160000
DTEND;TZID=Asia/Kolkata:20260313T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1695
DTSTAMP:20260306T092350Z
SUMMARY:The Natural Proofs Barrier Against Data Structure Lower Bounds
DESCRIPTION:Speaker: Tulasi Mohan Molli (BITS Pilani Hyderabad)\n\nAbstract
 : \nA long-standing challenge in Theoretical Computer Science is to prove 
 strong lower bounds for data structures in the cell probe model. Consider 
 a data structure problem with data from a set D\, queries from a set Q\, a
 nd in the dynamic case\, updates from a set U. The current state of the ar
 t in lower bounds is a query time of t = approximately on the order of log
  of |Q| (up to polylogarithmic factors) for static problems\, and max(tq\,
  tu) = approximately on the order of (log² n) for dynamic problems\, wher
 e tq and tu are the query and update times and n = max(|Q|\, |U|\, log |D|
 ). In this talk\, we address this barrier by porting the celebrated Natura
 l Proofs framework of Razborov and Rudich from circuit complexity to the d
 ata structure setting.This talk is based on joint work with Michal Koucký
 \, Bruno Loff\, and Michael Saks (STOC 2026) where we comprehensively surv
 ey the literature on data structure lower bounds in the cell probe model a
 nd show that almost all major proof techniques are natural within our fram
 ework. This includes static approaches like cell sampling and methods base
 d on communication complexity\, as well as dynamic techniques ranging from
  the classic chronogram method to the recent super-logarithmic lower bound
 s of Larsen and Yu [LY23]. We will also explore how these techniques conne
 ct to Coding Theory.Finally\, we will see our conjectured family of pseudo
 random data structure problems designed to fool the distinguishers inheren
 t in these proofs. If our conjecture holds\, then all natural lower bound 
 techniques (which encompass all known methods except one) are fundamentall
 y unable to improve upon the current state of the art.\nShort Bio: Tulasi
  Mohan Molli is an Assistant Professor in the Department of Computer Scien
 ce & Information Systems at BITS Pilani\, Hyderabad Campus. He was previou
 sly a Postdoctoral Researcher at the University of Lisbon. He earned his P
 hD from the Tata Institute of Fundamental Research (TIFR)\, Mumbai\, and h
 olds both a BSc (Honors) and an MSc from the Chennai Mathematical Institut
 e (CMI). He primarily works in Complexity Theory\, specifically exploring
   data structure lower bounds and the fundamental barriers to proving low
 er bounds in general.\n
URL:https://www.tcs.tifr.res.in/web/events/1695
DTSTART;TZID=Asia/Kolkata:20260317T160000
DTEND;TZID=Asia/Kolkata:20260317T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1702
DTSTAMP:20260320T045405Z
SUMMARY:Multi-party sampling
DESCRIPTION:Speaker: Hari Krishnan P A (TIFR)\n\nAbstract: \nThe problem in
  which multiple distrusting parties want to collaborate together and sampl
 e random variables which respect a certain joint distribution is called mu
 lti-party secure sampling. The talk will involve an introduction to the sa
 me\; particularly the special case where parties do not have an offline se
 tup. The characterization of distributions which can be sampled securely h
 as been known for 3 parties for many years. This would be main content of 
 the talk.\nIf time permits\, we will also see a recent result of ours\, a 
 4-party characterization for boolean distributions. This is a joint work w
 ith Keval Jain\, Manoj Prabhakaran and Vinod Prabhakaran.\n
URL:https://www.tcs.tifr.res.in/web/events/1702
DTSTART;TZID=Asia/Kolkata:20260320T160000
DTEND;TZID=Asia/Kolkata:20260320T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1676
DTSTAMP:20260324T052011Z
SUMMARY:Optimal Two-Round Communication Lower bound for Graph Connectivity
DESCRIPTION:Speaker: Rakesh Venkat (Indian Institute of Technology Hyderaba
 d (IITH))\n\nAbstract: \nHow much communication is required to determine w
 hether a distributed graph is connected? We study the randomized two-party
  communication complexity of Graph Connectivity\, where the edges of an 
  n-vertex graph are distributed between Alice and Bob\, and the goal is t
 o decide whether the union of their edges forms a connected graph.A classi
 c result of Hajnal\, Maass\, and Turán (STOC '88) shows that deterministi
 c protocols require $\\Omega(n \\log n)$ bits\, even with unlimited rounds
  of interaction. In contrast\, for randomized protocols with unbounded rou
 nds\, the best known lower bound via a reduction from Set Disjointness due
  to Babai\, Frankl\, and Simon (FOCS '86) is only $\\Omega(n)$. Closing th
 is gap has remained a long-standing open problem\, recently highlighted fo
 r its algorithmic significance by Apers et al. (FOCS '22). In this talk\,
  we show that any randomized two-round protocol for Graph Connectivity mus
 t communicate $\\Omega(n \\log n)$ bits\, matching the deterministic upper
  bound in this bounded-round setting. Our proof is based on a reduction fr
 om a restricted form of the Pointer Chasing problem\, originally studied b
 y Papadimitriou and Sipser (JCSS '84). Our reduction also allows us to ob
 tain $\\omega(n)$ lower bounds for any constant number of rounds\, by exte
 nding deterministic pointer-chasing bounds in prior work by Ponzio\, Radha
 krishnan\, and Venkatesh (JCSS '01) to the randomized setting. This is jo
 int work with Jaikumar Radhakrishnan (ICTS-TIFR\, Bengaluru) and Chaitanya
  Reddy (IIT Hyderabad).\nShort Bio: Rakesh Venkat is a faculty member at t
 he Indian Institute of Technology Hyderabad. He received his Ph.D. from th
 e Tata Institute of Fundamental Research (TIFR)\, Mumbai. His research int
 erests lie in approximation algorithms and computational complexity theory
 .\n
URL:https://www.tcs.tifr.res.in/web/events/1676
DTSTART;TZID=Asia/Kolkata:20260325T143000
DTEND;TZID=Asia/Kolkata:20260325T153000
LOCATION:A-201 Seminar Room
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1703
DTSTAMP:20260326T091123Z
SUMMARY:Catalytic Graph Algorithms
DESCRIPTION:Speaker: Shubham Bhardwaj (TIFR)\n\nAbstract: \nCatalytic compu
 tation asks: how much does access to a full but reusable tape amplify our 
 computational power? In this talk\, we explore this question in the contex
 t of graph algorithms and logspace complexity.\nWe present three results: 
 NL ⊆ CL\, showing that nondeterministic logspace computations can be sim
 ulated catalytically\; BPL ⊆ CL\, showing the same for randomized logspa
 ce\; and the collapse CBPL = CNL = CL\, revealing that in the catalytic re
 gime\, nondeterminism and randomness likely afford no additional power ove
 r determinism — a striking contrast to the standard logspace world where
  such separations remain wide open.\nWe also discuss some key design princ
 iples that underpin catalytic algorithms.\n
URL:https://www.tcs.tifr.res.in/web/events/1703
DTSTART;TZID=Asia/Kolkata:20260327T160000
DTEND;TZID=Asia/Kolkata:20260327T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1648
DTSTAMP:20260401T061254Z
SUMMARY:Saral AI: Democratising Scholarly Work by Transforming into Accessi
 ble\, Multilingual Content
DESCRIPTION:Speaker: Ponnurangam Kumaraguru (IIIT Hyderabad)\n\nAbstract: \
 nHave you ever considered transforming a research paper—your own or one 
 you are reading—into a short video\, poster\, slide deck\, reel\, podcas
 t\, or a social media post? This talk introduces SARAL AI\, an open-source
 \, AI-enabled research platform designed to democratise access to research
  and enable large-scale knowledge diffusion.Developed with the support of 
 Anusandhan National Research Foundation (ANRF)\, Saral AI enables research
 ers to convert scholarly artifacts such as research papers and patents int
 o multiple reusable and accessible formats\, including videos\, slide deck
 s\, posters\, reels\, podcasts\, and social media content. By lowering tec
 hnical and communication barriers\, SARAL supports researchers\, educators
 \, and institutions in amplifying the reach and impact of their work. SARA
 L also enables researchers to consume scholarly content in multiple format
 s and languages\, supporting inclusive and accessible knowledge engagement
 .A key capability of Saral AI is multilingual video generation\, with outp
 uts currently supported in Assamese\, Bengali\, Bodo\, Dogri\, English\, G
 ujarati\, Hindi\, Kannada\, Maithili\, Malayalam\, Manipuri\, Marathi\, Od
 ia\, Punjabi\, Sanskrit\, Santali\, Tamil\, Telugu\, and Urdu\, enabling r
 esearch communication at population scale.The session will include a hands
 -on component\; participants are encouraged to bring their own research pa
 per(s) and a laptop so that they can actively use the Saral platform durin
 g the session. The talk will also cover the platform architecture\, workfl
 ows\, and adoption experiences.The Saral AI platform is accessible at http
 s://saral.democratiseresearch.in/   and its open-source codebase is avai
 lable at https://github.com/DemocratiseResearch/SARAL \n \nShort Bio: 
 Ponnurangam Kumaraguru (“PK”) is a professor of Computer Science at II
 IT-Hyderabad and a Fellow of the Indian National Academy of Engineering. H
 e is a vice president of the ACM India Council and an ACM distinguished me
 mber and a distinguished speaker. PK received his Ph.D. from Carnegie Mell
 on University. His research focuses on cybersecurity\, computational socia
 l science\, and responsible AI\, and he currently leads the development of
  SARAL AI\, an open-source platform for democratizing research and making 
 it more accessible. PK also leads PreCog\, a research group at IIIT-Hydera
 bad.\n
URL:https://www.tcs.tifr.res.in/web/events/1648
DTSTART;TZID=Asia/Kolkata:20260407T160000
DTEND;TZID=Asia/Kolkata:20260407T170000
LOCATION:Lecture Theatre (AG-66)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1704
DTSTAMP:20260408T084437Z
SUMMARY:On Approximability of Satisfiable CSPs & Applications
DESCRIPTION:Speaker: Amey Bhangale (UNIVERSITY OF CALIFORNIA)\n\nAbstract: 
 \nThe satisfiability problem for Constraint Satisfaction Problems (CSPs) a
 sks whether a CSP instance admits an assignment that satisfies all constra
 ints. For a k-ary predicate P:[q]^k -> {0\,1}\, where P(x)=1 iff x satisfi
 es the constraint\, the problem CSP(P) consists of constraints obtained by
  applying P to ordered k-tuples of variables. By the Dichotomy Theorem of 
 Bulatov and Zhuk\, this problem is either in P or NP-complete. A natural q
 uestion is to determine the threshold \\alpha(P) < 1 for each NP-complete 
 CSP(P) such that (i) there is a polynomial-time algorithm that finds an as
 signment satisfying an \\alpha(P) fraction of constraints on satisfiable i
 nstances\, and (ii) for every \\epsilon>0\, finding an assignment satisfyi
 ng an (\\alpha(P)+\\epsilon) fraction is NP-hard. While such thresholds ar
 e known for some predicates (e.g.\, 7/8 for 3SAT by Hastad)\, determining 
 \\alpha(P) in general remains widely open.This talk presents recent work i
 nitiating a systematic study of this question\, including new analytical t
 heorems and a proposed approximation algorithm. I will also discuss applic
 ations to additive combinatorics\, including improved bounds for sets avoi
 ding restricted 3-term arithmetic progressions and results related to the 
 density Hales--Jewett theorem in [3]^n.The talk will be based on joint wor
 ks with Subhash Khot\, Yang P. Liu\, and Dor Minzer.\n \nShort Bio : Amey
  Bhangale is currently an Assistant Professor in the CSE Department at the
  University of California\, Riverside. He completed his PhD at the Rutgers
  University in 2017 under the supervision of Swastik Kopparty. He subseque
 ntly held postdoctoral positions at the Weizmann Institute of Science (hos
 ted by Irit Dinur) and was a research fellow at the Simons Institute for t
 he Theory of Computing. His research interests include approximation algor
 ithms\, probabilistically checkable proofs\, hardness of approximation\, a
 nd analysis of Boolean functions.\n
URL:https://www.tcs.tifr.res.in/web/events/1704
DTSTART;TZID=Asia/Kolkata:20260409T140000
DTEND;TZID=Asia/Kolkata:20260409T150000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1705
DTSTAMP:20260408T084515Z
SUMMARY:On Approximability of Satisfiable CSPs & Applications (extended ver
 sion)
DESCRIPTION:Speaker: Amey Bhangale (UNIVERSITY OF CALIFORNIA)\n\nAbstract: 
 \nThe satisfiability problem for Constraint Satisfaction Problems (CSPs) a
 sks whether a CSP instance admits an assignment that satisfies all constra
 ints. For a k-ary predicate P:[q]^k -> {0\,1}\, where P(x)=1 iff x satisfi
 es the constraint\, the problem CSP(P) consists of constraints obtained by
  applying P to ordered k-tuples of variables. By the Dichotomy Theorem of 
 Bulatov and Zhuk\, this problem is either in P or NP-complete. A natural q
 uestion is to determine the threshold \\alpha(P) < 1 for each NP-complete 
 CSP(P) such that (i) there is a polynomial-time algorithm that finds an as
 signment satisfying an \\alpha(P) fraction of constraints on satisfiable i
 nstances\, and (ii) for every \\epsilon>0\, finding an assignment satisfyi
 ng an (\\alpha(P)+\\epsilon) fraction is NP-hard. While such thresholds ar
 e known for some predicates (e.g.\, 7/8 for 3SAT by Hastad)\, determining 
 \\alpha(P) in general remains widely open.This talk presents recent work i
 nitiating a systematic study of this question\, including new analytical t
 heorems and a proposed approximation algorithm. I will also discuss applic
 ations to additive combinatorics\, including improved bounds for sets avoi
 ding restricted 3-term arithmetic progressions and results related to the 
 density Hales--Jewett theorem in [3]^n.The talk will be based on joint wor
 ks with Subhash Khot\, Yang P. Liu\, and Dor Minzer.\n \nShort Bio : Amey
  Bhangale is currently an Assistant Professor in the CSE Department at the
  University of California\, Riverside. He completed his PhD at the Rutgers
  University in 2017 under the supervision of Swastik Kopparty. He subseque
 ntly held postdoctoral positions at the Weizmann Institute of Science (hos
 ted by Irit Dinur) and was a research fellow at the Simons Institute for t
 he Theory of Computing. His research interests include approximation algor
 ithms\, probabilistically checkable proofs\, hardness of approximation\, a
 nd analysis of Boolean functions.\n
URL:https://www.tcs.tifr.res.in/web/events/1705
DTSTART;TZID=Asia/Kolkata:20260410T160000
DTEND;TZID=Asia/Kolkata:20260410T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1708
DTSTAMP:20260417T050127Z
SUMMARY:Quantum Classical Equivalence for AND Functions
DESCRIPTION:Speaker: Sreejata Kishor  Bhattacharya (TIFR)\n\nAbstract: \nA 
 major open problem at the interface of quantum computing and communication
  complexity is whether quantum protocols can be exponentially more efficie
 nt than classical protocols for computing total Boolean functions\; the pr
 evailing conjecture is that they are not. In a seminal work\, Razborov (20
 02) resolved this question for AND-functions of the form\nF(x\, y)=f(x_1\,
  y_1\, ...\, x_n\, y_n)\n \nwhen the outer function f is symmetric\, by p
 roving that their bounded-error quantum and classical communication comple
 xities are polynomially related. Since then\, extending this result to all
  AND-functions has remained open and has been posed by several authors.\n
  \nIn this work\, we settle this problem. We show that for every Boolean 
 function f\, the bounded-error quantum and classical randomized communicat
 ion complexities of the AND-function f • AND_2 are polynomially related\
 , up to polylogarithmic factors in n. Moreover\, modulo such polylogarithm
 ic factors\, we prove that the bounded-error quantum communication complex
 ity of f • AND_2 is polynomially equivalent to its deterministic communi
 cation complexity\, and that both are characterized—up to polynomial los
 s—by the logarithm of the De Morgan sparsity of f.\n \nOur results buil
 d on the recent work of Chattopadhyay\, Dahiya\, and Lovett (2025) on stru
 ctural characterizations of non-sparse Boolean functions\, which we extend
  to resolve the conjecture for general AND functions.\n \nBased on joint 
 work with Farzan Byramji\, Arkadev Chattopadhyay\, Yogesh Dahiya\, and Sha
 char Lovett.\n
URL:https://www.tcs.tifr.res.in/web/events/1708
DTSTART;TZID=Asia/Kolkata:20260417T160000
DTEND;TZID=Asia/Kolkata:20260417T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1690
DTSTAMP:20260407T043058Z
SUMMARY:A Distribution Testing Approach to Clustering Distributions
DESCRIPTION:Speaker: Gunjan Kumar (IIT Kanpur)\n\nAbstract: \nWe study th
 e following distribution clustering problem: given a hidden partit
 ion of distributions into two groups such that the distributions
  within each group are identical\, and the two distributions cor
 responding to the two clusters are far apart\, the goal is to 
 recover the partition. We establish upper and lower bounds on th
 e sample complexity for two fundamental cases: (1) when one of t
 he cluster distributions is known\, and (2) when both distribution
 s are unknown.  Our upper and lower bounds characterize the sample comp
 lexity’s dependence on the domain size n\, number of distributions k\, s
 ize of one of the cluster r and distance ε.  In particular\, we achieve 
 tightness with respect to (n\,k\,r\,ε) (upto log factors) across all regi
 mes.\nShort Bio: Gunjan Kumar is currently an Assistant Professor at IIT 
 Kanpur. He completed his PhD at the Tata Institute of Fundamental Research
  (TIFR)\, Mumbai\, and subsequently held a postdoctoral position at the Sc
 hool of Computing\, National University of Singapore. His research interes
 ts include sublinear algorithms\, property testing\, and statistical estim
 ation problems in small-sample regimes.\n
URL:https://www.tcs.tifr.res.in/web/events/1690
DTSTART;TZID=Asia/Kolkata:20260421T160000
DTEND;TZID=Asia/Kolkata:20260421T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1711
DTSTAMP:20260424T043604Z
SUMMARY:Teaching Your Computer to Play Chess (Part 1): Markov Games and TD 
 Learning
DESCRIPTION:Speaker: Aakash Ghosh (TIFR)\n\nAbstract: \nHow do we mathemati
 cally formulate the problem of learning to play a game as complex as chess
 ? In the first part of this two-part series\, we will approach chess throu
 gh  the lens of Reinforcement Learning and Stochastic Approximation. We b
 egin by formalizing the game as a two-player zero-sum Markov Decision Proc
 ess\, discussing the Bellman Optimality Equation and minimax equilibria.\n
URL:https://www.tcs.tifr.res.in/web/events/1711
DTSTART;TZID=Asia/Kolkata:20260424T160000
DTEND;TZID=Asia/Kolkata:20260424T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1669
DTSTAMP:20260428T082202Z
SUMMARY:Learning world models from doing and seeing: Causal representation 
 learning and applications to robot pose estimation
DESCRIPTION:Speaker: Karthikeyan Shanmugam (Google Deepmind India (Bengalur
 u))\n\nAbstract: \n\nCausal Representation Learning aims to disentangle la
 tent generative factors that give rise to high dimensional observations by
  acting in the world and seeing changes in the observations very similar t
 o humans learning world models.  An example in robotics is when the robot
 's state is physical but you observe an image of the robot from a specific
  camera view. In general\, we observe only the high dimensional transforma
 tion (as images etc.) of the true causal variable that matter for a downst
 ream task. The central problem in causal representation learning is to inv
 ert the unknown transformation between true causal variables and the obser
 vations up to coordinate-wise scaling and permutation. ICA literature deal
 t with this problem when variables are independent or conditionally indepe
 ndent. The goal here is to generalize to causally interacting variables us
 ing interventional datasets. We show that this is possible with enough int
 erventional diversity by exploiting two key ideas: a) Represent interventi
 onal distributions in terms of their scores (gradient of likelihoods). b) 
 The encoder-decoder pair that minimizes reconstruction loss and sparsifies
  the score difference in the latent space is the optimal pair. We show var
 ious versions of these results for linear and general transforms\, assumin
 g mild regularity on the diversity of interventions. We also will discuss 
 recent empirical results on scaling this up into a learning algorithm for 
 robot pose estimation.Joint work with Burak Varici (CMU)\, Emre Acarturk (
 RPI)\, Abhishek Kumar (Amazon\, ex-GDM)\, Ali Tajer (RPI). Talk is based o
 n papers (https://arxiv.org/abs/2510.20884\, https://arxiv.org/abs/2402.0
 0849)\nShort Bio: Karthikeyan Shanmugam is currently a Research Scientist 
 at Google DeepMind India (Bengaluru) in the Machine Learning and Optimizat
 ion Team since April 2022. Previously\, he was a Research Staff Member an
 d a Herman Goldstine Postdoctoral Fellow at IBM Research\, NY in the per
 iod 2016-2022. He obtained his Ph.D. from UT Austin in 2016\, B. Tech and
  M. Tech Degrees from IIT Madras in 2010\, all in Electrical Engineering.
   He received the IBM Corporate Technical Award in 2021 for his work on
  Trustworthy AI. His main research interests are in Machine Learning spa
 nning Causal inference\, Online learning and Foundation models.\n
URL:https://www.tcs.tifr.res.in/web/events/1669
DTSTART;TZID=Asia/Kolkata:20260428T160000
DTEND;TZID=Asia/Kolkata:20260428T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1682
DTSTAMP:20260421T061751Z
SUMMARY:Likes\, Budgets\, and Equilibria: Designing Contests for Socially O
 ptimal Advertising
DESCRIPTION:Speaker: Swaprava Nath (IIT Bombay)\n\nAbstract: \nFirms (busin
 esses\, service providers\, entertainment organizations\, political partie
 s\, etc.) advertise on social networks to draw people's attention and impr
 ove their awareness of the brands of the firms. In all such cases\, the co
 mpetitive nature of their engagements gives rise to a game where the firms
  need to decide how to distribute their budget over the consumers on a net
 work to maximize their brand's awareness. The firms (players) need to opti
 mize the budget allocation to the vertices (consumers) of the network so t
 hat the spread improves via direct (e.g.\, advertisements or free promotio
 nal offers) and indirect marketing (e.g.\, word-of-mouth). We propose a tw
 o-timescale model of decisions\, where communication between vertices occu
 rs on a faster timescale and the strategy update of firms occurs on a slow
 er timescale. We show that under fairly standard conditions\, the best res
 ponse dynamics of the firms converge to a pure strategy Nash equilibrium. 
 However\, such equilibria can be away from a socially optimal one. We prov
 ide a characterization of the contest success functions and provide exampl
 es for the designers of such contests (e.g.\, regulators\, social network 
 providers\, etc.) such that the Nash equilibrium becomes unique and social
  welfare maximizing. Our experiments show that for realistic scenarios\, s
 uch contest success functions perform fairly well.\nThis is a joint work w
 ith Sayantika Mandal and Harman Agarwal.\nShort bio: Swaprava is a faculty
  member in the Department of Computer Science and Engineering at IIT Bomba
 y\, and an associated faculty member of the Centre for Machine Intelligenc
 e and Data Science (CMInDS) and the IIT Bombay Trust Lab. He is the foundi
 ng faculty member of the Computational Economics Group (CompEcon) at IIT B
 ombay\, and previously served as a faculty member at IIT Kanpur. He has he
 ld postdoctoral positions at Carnegie Mellon University and the Indian Sta
 tistical Institute\, New Delhi\, and received his PhD from the Indian Inst
 itute of Science\, Bangalore. His research lies at the intersection of eco
 nomics and computation\, with applications to Internet economics\, auction
 s\, matching markets\, resource allocation\, crowdsourcing\, online advert
 ising\, and social networks.\n
URL:https://www.tcs.tifr.res.in/web/events/1682
DTSTART;TZID=Asia/Kolkata:20260505T160000
DTEND;TZID=Asia/Kolkata:20260505T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1713
DTSTAMP:20260505T050626Z
SUMMARY:Deterministic Algorithms for Factors of Constant-Depth Arithmetic C
 ircuits
DESCRIPTION:Speaker: Varun Ramanathan (TIFR)\n\nAbstract: \nMultivariate po
 lynomial factorization is a fundamental algebraic problem with connections
  to error-correcting codes\, pseudorandomness and complexity theory. Const
 ant-depth circuits are a natural way to capture algebraic computation tha
 t is highly parallelizable. In this talk\, we will try and understand some
  of the ideas that went into a recent line of work that concluded with a d
 eterministic factorization algorithm for constant-depth circuits. More gen
 erally\, we will see that for most natural algebraic models\, deterministi
 c (black-box) polynomial identity testing is sufficient for deterministic 
 factorization.At the heart of these algorithmic results\, we will use poly
 nomial identity testing to project multivariate polynomials to univariate 
 polynomials while preserving information about the factors. The final algo
 rithmic result in this line of work builds upon a recent surprising and im
 portant structural result: constant-depth circuits (and most natural algeb
 raic models) are closed under factoring -- if a polynomial has a constant-
 depth circuit\, then so do its factors.  This talk will be based on colla
 borations with Somnath Bhattacharjee\, Mrinal Kumar\, Shanthanu Suresh Rai
 \, Ramprasad Saptharishi\, Shubhangi Saraf and Ben Lee Volk.\n
URL:https://www.tcs.tifr.res.in/web/events/1713
DTSTART;TZID=Asia/Kolkata:20260507T163000
DTEND;TZID=Asia/Kolkata:20260507T173000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1716
DTSTAMP:20260508T043152Z
SUMMARY:Teaching your computer to play chess (Part 2): Bandits\, MCTS\, and
  Approximate Policy Iteration
DESCRIPTION:Speaker: Aakash Ghosh (TIFR)\n\nAbstract: \nBuilding on the the
 oretical limitations of pure TD-learning explored in Part 1\, how do moder
 n neural engines like AlphaZero actually master the game? In the second pa
 rt of this series\, we shift our focus to local search framed as a sequent
 ial decision-making problem under uncertainty. We will introduce the Multi
 -Armed Bandit problem and the UCB1 algorithm\, extending these concepts to
  game trees via Monte Carlo Tree Search (MCTS). Finally\, we will deconstr
 uct the AlphaZero framework\, demonstrating how it utilizes MCTS as a form
 al policy improvement operator to perform Approximate Policy Iteration and
  successfully evade the "Deadly Triad" of deep reinforcement learning.\n
URL:https://www.tcs.tifr.res.in/web/events/1716
DTSTART;TZID=Asia/Kolkata:20260508T160000
DTEND;TZID=Asia/Kolkata:20260508T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1709
DTSTAMP:20260429T055402Z
SUMMARY:Reconstruction of Depth 3 Arithmetic circuits with constant top fan
 -in
DESCRIPTION:Speaker: Devansh Shringi (University of Toronto)\n\nAbstract: \
 nWe consider the problem of reconstructing (exact learning) arithmetic cir
 cuits given blackbox access to evaluations of the polynomial computed by t
 he circuit. This problem is closely connected to central questions in alge
 braic complexity\, including circuit lower bounds\, polynomial identity te
 sting (PIT)\, and tensor decomposition.The focus of the talk will be on de
 pth-3 circuits with bounded top fan-in and on understanding their structur
 e. We study identities computed by such circuits and analyze the set of co
 nstant-codimension subspaces on which these polynomials vanish. These stru
 ctural insights lead to a quasi-polynomial time algorithm for reconstructi
 ng depth-3 circuits with any constant top fan-in. Prior subexponential rec
 onstruction algorithms for this model were known only when the top fan-in 
 is 2 (Sinha '16\, '22) or 3 (Saraf-Shringi '25)\, or when the underlying f
 ield is small (Karnin-Shpilka '09).This talk is based on joint work with S
 hubhangi Saraf and Narmada Varadarajan (https://eccc.weizmann.ac.il/report
 /2025/222/)(to appear in STOC26).\n \nShort Bio : Devansh is a fourth yea
 r PhD student at University of Toronto\, where he works with Shubhangi Sar
 af. Before that he was an undergraduate at IIT Kanpur. His research intere
 sts are in algebraic complexity\, computational complexity\, computational
  algebra \\& number theory and pseudorandomness. \n \n
URL:https://www.tcs.tifr.res.in/web/events/1709
DTSTART;TZID=Asia/Kolkata:20260512T160000
DTEND;TZID=Asia/Kolkata:20260512T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1714
DTSTAMP:20260511T053246Z
SUMMARY:Rare Events in Stochastic Multi-Armed Bandits
DESCRIPTION:Speaker: Anirban Bhattacharjee (TIFR)\n\nAbstract: \nWe examine
  stochastic multi-armed bandit (MAB) problems in rare event regimes with e
 mphasis on Best Arm Identification (BAI) and also touch upon regret minimi
 zation. When arm rewards occur infrequently but are high in magnitude\, we
  develop algorithms for BAI which are based on Poisson approximation and d
 rastically reduce computational effort at the cost of negligible increase 
 in sample complexity. For identifying the safest system among a given set 
 of safety-critical systems with rare failures\, we consider simulation mod
 els of the systems\, and simulate from them following BAI methods. Reasona
 bly accurate approximations of the lower bound on sample complexity reveal
  that sample complexity depends on the failure rate of the second-best sys
 tem\, as opposed to the best. Further\, standard regret minimization algor
 ithms are shown to perform poorly in rare-event regimes where rewards are 
 high-value but rarely seen\, necessitating scaled modifications that ensur
 e optimality.\n
URL:https://www.tcs.tifr.res.in/web/events/1714
DTSTART;TZID=Asia/Kolkata:20260514T160000
DTEND;TZID=Asia/Kolkata:20260514T170000
LOCATION:A-201 and Zoom
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1706
DTSTAMP:20260504T054522Z
SUMMARY:Markov Chains with Rewinding
DESCRIPTION:Speaker: Madhu Sudan (Harvard University)\n\nAbstract: \nThe ta
 sk of trying to identify the (most likely) Markov Chain that generates a s
 equence is a classical problem in probabilistic inference. In this talk we
  introduce a twist to this classical problem motivated by the tasking of l
 earning/understanding the power of randomized algorithms. In our mode\, wh
 ich we call Markov Chains with Rewinding\, the learner either gets to ask 
 the chain to continue from its current state and produce the next signal\,
  or gets to rewind the chain to a previous time and then proceed from ther
 e. This increases the information one can learn about the underlying chain
 \; and techniques to bound the amount of information learned turn out to b
 e a powerful tool in the analysis of sublinear time algorithms (notably in
  the works of Behnezhad\, Roghani and Rubinstein\, STOC 2023\, FOCS 2023\,
  and STOC 2024). While this model arose implicitly in these previous works
 \, in this work we study this systematically for the first time and develo
 p rewinding strategies that are competitive with the best possible ones in
  terms of the number of signals needed to identify the chain. Along the wa
 y we identify an important subclass of rewinding strategies\, namely non-a
 daptive ones\, and show their power.In the talk I will introduce the model
 \, explain how special cases (involving a constant number of states) play 
 a role in many previous lower bounds\, before turning to our general analy
 ses.Based on this joint work with Amir Azarmehr\, Soheil Behnezhad\, Alma
  Ghafari (all at Northeastern U.)\nShort Bio: Madhu Sudan is Gordon McKay 
 Professor at Harvard's John A. Paulson School of Engineering and Applied S
 ciences. He got his B.Tech. from IIT Delhi and Ph.D. from UC Berkeley and 
  previously held positions at IBM Research\, MIT\, and Microsoft Research
 . His research focuses on the mathematical foundations of communication an
 d computation in general\, and in particular on questions about probabilis
 tically checkable proofs\, list decoding of error correcting codes\, prope
 rty testing\, sublinear time algorithms and communication in the presence 
 of uncertainty. \n
URL:https://www.tcs.tifr.res.in/web/events/1706
DTSTART;TZID=Asia/Kolkata:20260519T160000
DTEND;TZID=Asia/Kolkata:20260519T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1715
DTSTAMP:20260505T063403Z
SUMMARY:To be announced
DESCRIPTION:Speaker: Tanmay Inamdar (IIT Jodhpur)\n\nAbstract: \nTo be anno
 unced\n
URL:https://www.tcs.tifr.res.in/web/events/1715
DTSTART;TZID=Asia/Kolkata:20260526T160000
DTEND;TZID=Asia/Kolkata:20260526T170000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1717
DTSTAMP:20260511T053704Z
SUMMARY:Adversarial Hypothesis Testing: Channel Estimation\, Sequentiality 
 and Robustness
DESCRIPTION:Speaker: Eeshan Modak (TIFR)\n\nAbstract: \n\nIn this thesis\, 
 we study the following problems:\nAdversarial hypothesis testing is a mode
 l for problems where the observed data is not independent and identically 
 distributed according to a fixed distribution. The samples could instead c
 ome from distributions arbitrarily chosen by an adversary. We show how seq
 uential tests can obtain a strictly better performance compared to fixed l
 ength tests in this setting.\nArbitrarily Varying Channels (AVCs) model ch
 annels which can vary with time in an arbitrary way during the transmissio
 n. We study the problem of distinguishing between two AVCs where the trans
 mitter (i) is deterministic\, (ii) may privately randomize\, and (iii) sha
 res randomness with the detector.\n In many practical hypothesis testing 
 problems\, our hypotheses might not exactly model the observed data. In su
 ch a situation\, we would like our test to output the hypothesis which is 
 closer to the true distribution of the underlying data. It turns out that 
 this is possible only when the hypotheses are not too close. We give a low
 er bound on the optimal separation when the closeness is measured in terms
  of the Hellinger distance.\nObtaining bounds on the expected generalizati
 on error of a machine learning algorithm is an important problem. We obtai
 n a family of Rényi divergence-based bounds that recover some of the exis
 ting bounds as a special case. Also\, for certain values of the Rényi par
 ameter\, they can be tighter than the existing bounds.\n
URL:https://www.tcs.tifr.res.in/web/events/1717
DTSTART;TZID=Asia/Kolkata:20260529T103000
DTEND;TZID=Asia/Kolkata:20260529T113000
LOCATION:A-201 (STCS Seminar Room)
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1712
DTSTAMP:20260427T043043Z
SUMMARY:To be Announced
DESCRIPTION:Speaker: Anand Louis (Indian Institute of Science\, Bengaluru)\
 n\nAbstract: \nTo be announced \n
URL:https://www.tcs.tifr.res.in/web/events/1712
DTSTART;TZID=Asia/Kolkata:20260609T160000
DTEND;TZID=Asia/Kolkata:20260609T170000
LOCATION:A201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1707
DTSTAMP:20260504T044758Z
SUMMARY:New Upper Bounds for Howard's Policy Iteration
DESCRIPTION:Speaker: Shivaram Kalyanakrishnan (IIT Bombay)\n\nAbstract: \nH
 oward's Policy Iteration (HPI) is a classic algorithm for solving Markov D
 ecision Problems (MDPs). HPI uses a "greedy" switching rule to update from
  any non-optimal policy to a dominating one\, iterating until an optimal p
 olicy is found. Although HPI has existed for over 60 years\, and is remark
 ably efficient in practice\, theoretical analysis has struggled to explain
  its efficiency. On MDPs wth n states and 2 actions per state\, the number
  of policies is 2^{n}\; this number is a trivial upper bound on the number
  of iterations taken by HPI. Interestingly\, the tightest upper bounds kno
 wn for the same quantity is O(2^{n}/n)\, a mere linear-factor improvement.
  In contrast\, the tightest known lower bound is Omega(n). In this talk\,
  I will present two recent results\, which establish tighter upper bounds 
 on the running time of HPI on restricted classes of MDPs. On MDPs whose tr
 ansitions are all deterministic (DMDPs)\, we show an upper bound of poly(n
 ) \\phi^{n} iterations\, where \\phi is the golden ratio 1.618.... This re
 sult marks an exponential improvement over Mansour and Singh's bound of O(
 2^{n}/n) for general MDPs. Further\, in DMDPs with rewards of constant bit
 -size\, we furnish a subexponential-in-n upper bound. Our results emerge f
 rom contrasting lines of anlaysis: the first from a count of cycles in a f
 amily of digraphs\, and the second from a root-separation bound for univar
 iate polynomials.\nShort Bio : Shivaram Kalyanakrishnan is an Associate Pr
 ofessor in the Department of Computer Science and Engineering at the India
 n Institute of Technology Bombay. His research interests include artificia
 l intelligence and machine learning\, spanning topics such as sequential d
 ecision making\, multi-agent learning\, multi-armed bandits\, and humanoid
  robotics. Kalyanakrishnan received a Ph.D. in computer science from the U
 niversity of Texas at Austin. Subsequently he was a Research Scientist at 
 Yahoo Labs Bangalore and an INSPIRE Faculty Fellow at the Indian Institute
  of Science\, Bangalore. Kalyanakrishnan works on both theoretical and app
 lied problems. He heads e-Yantra\, a large-scale outreach programme that a
 nnually trains thousands of students in robotics.\n
URL:https://www.tcs.tifr.res.in/web/events/1707
DTSTART;TZID=Asia/Kolkata:20260623T160000
DTEND;TZID=Asia/Kolkata:20260623T170000
LOCATION:A-201
END:VEVENT
BEGIN:VEVENT
UID:www.tcs.tifr.res.in/event/1710
DTSTAMP:20260504T045108Z
SUMMARY:To be Announced
DESCRIPTION:Speaker: Sushmita Gupta (The Institute of Mathematical Sciences
 )\n\nAbstract: \nTo be Announced \n
URL:https://www.tcs.tifr.res.in/web/events/1710
DTSTART;TZID=Asia/Kolkata:20260721T160000
DTEND;TZID=Asia/Kolkata:20260721T170000
LOCATION:A201
END:VEVENT
BEGIN:VTIMEZONE
TZID:Asia/Kolkata
BEGIN:STANDARD
DTSTART:20000101T150000
TZNAME:IST
TZOFFSETTO:+0530
TZOFFSETFROM:+0530
END:STANDARD
END:VTIMEZONE
END:VCALENDAR