2004-2005 seminars

Nov
15
2004

Computer Science/Discrete Mathematics Seminar I

On Sensitivity and Chaos
Elchanan Mossel
11:15am|S-101

I will discuss some (very) recent results showing how techniques from the theory of Gaussian Hilbert spaces can be used in order to solve a number of open problems regarding boolean functions with low influences. I will survey some of the background...

Nov
09
2004

Computer Science/Discrete Mathematics Seminar II

Slow Mixing of Local Dynamics for Colourings and Independent Sets
David Galvin
10:30am|S-101

We consider "local-update" Markov chains for sampling from independent sets and proper 3-colourings of a graph. An example of such a chain is the well-known Glauber dynamics, which updates the state of at most one vertex of the graph at each step...

Nov
08
2004

Computer Science/Discrete Mathematics Seminar I

Approximation Algorithms for Embeddings into Low-Dimensional Spaces
Piotr Indyk
11:15am|S-101

A low-distortion embedding between two metric spaces is a mapping which preserves the distances between each pair of points, up to a small factor called distortion. Low-distortion embeddings have recently found numerous applications in computer...

Nov
01
2004

Computer Science/Discrete Mathematics Seminar I

Influences and Decision Tree Complexity
11:15am|S-101

In this talk, I'll present a new inequality which, for an arbitrary boolean function, relates the influence of its variables to decision tree computation of the function. Combining this with another inequality due to Schramm and Steif, we deduce new...

Oct
26
2004

Computer Science/Discrete Mathematics Seminar II

Explicit Constructions of Bipartite Ramsey Graphs
Boaz Barak and Guy Kindler
10:30am|S-101

The main goal of this talk will be to present a proof of the following theorem. Theorem 1: For every fixed \delta >0 here is a polynomial time (in n = log N) computable function(s) f:[N]x[N]-->{0,1}, for which the following hold. For every two sets...

Oct
25
2004

Computer Science/Discrete Mathematics Seminar I

Tic-Tac-Toe Games: Exact Values of Infinitely Many Game Numbers
Jozsef Beck
11:15am|S-101

Ordinary 3-by-3 tic-tac-toe is trivial; the 3-dimensional 4-by-4-by-4 version is interesting but very complicated (first player wins; solved by Patashnik; heavy computer use); and the 5-by-5-by-5 version is already unsolved (expected to be a draw)...

Oct
12
2004

Computer Science/Discrete Mathematics Seminar II

The Intersection of a Matroid and a Simplicial Complex
10:30am|S-101

A classical theorem of Edmonds provides a min-max formula relating the maximal size of a set in the intersection of two matroids to a ``covering" parameter. In this talk we generalize this theorem, replacing one of the matroids by a general...