The authors adopt a utilitarian perspective on social choice, assuming that agents have (possibly latent) utility functions over some space of alternatives. For many reasons one might consider mechanisms, or social choice functions, that only have access to the ordinal rankings of alternatives by the individual agents rather than their utility functions. In this context, one possible objective for a social choice function is the maximization of (expected) social welfare relative to the information contained in these rankings. In the talk, we will focus on the worst case model (distortion) of the paper.
The link of the paper: https://www.sciencedirect.com/science/article/pii/S0004370215000892