The class of Unambiguous Star-free regular languages over words has been variously characterized in the past by logics such as the fragments $\Delta_2[<]$ and $FO^2[<]$ of first-order definable languages, Unary Temporal Logic $TL[F,P]$ as we
Given an m x n matrix A, we define the rank-k approximation of A as a matrix B of same size and of rank at most k such that A and B are close in the Frobenius norm.
+ Tom Kurtz, in a classic paper from 1972, showed that stochastic models for chemical reactions and deterministic models are related: in the limit of volume going to infinity, the stochastic model approaches the deterministic model.
Let us consider a natural generalization of the Partial Vertex Cover problem. Here, an instance consists of a graph $G = (V,E)$, a cost function $c : V -> Z^{+}$, a partition $P_{1}, . . .