Some computational and combinatorial applications of simplicial topology ABSTRACT: The well-known Sperner Lemma occupies a central role in the field of simplicial topology. It is known to be essentially equivalent to the famous Brouwer fixed-point theorem, to the no-retraction theorem and other fundamental facts in topology. Over the years Sperner's Lemma has found applications in many other fields including various parts of computer science, mathematical economics and combinatorics. In this talk I will recall Sperner's Lemma and show in detail a recent application in distributed computing (from a joint work with Y. Afek, U. Feige, E. Gafni and B. Sudakov). If time permits, I will also speak briefly about two other beautiful applications of simplicial topology - Kahn, Saks and Sturtevant's work on evasiveness of graph properties and Aharoni and Haxell's work on matchings in hypergraphs. No background in topology is required to follow this talk. BIO: Nati Linial is a Professor of computer science at the Hebrew University, Jerusalem and a frequent visitor to MSR. His work has had major influence on several areas of computer Science and combinatorics; In particular he initiated the study of cover times for random walks and (with Miki Ben Or) of the influence of variables on Boolean functions. See http://www.cs.huji.ac.il/~nati/