Mar. 19    COMBINATORICS SEMINAR  [C.Haase, L.Matusevich]
           (1) Tamas Hausel, UCB:  891 Evans,  1:30pm
               Combinatorics via topology of moduli spaces: 
               From Kneser's to Borsuk's problem
   In this talk, following the general idea of this term's Combinatorics
   seminar, we show some ways to apply topological methods in Combinatorics
   problems. We will explain the topological roots of three problems in
   Combinatorics: the Kneser problem about the chromatic number of the Kneser
   graph (following Lovasz & Barany), the problem of drawing a cube into a
   3-dimensional symmetric convex body and the problem of covering a
   diameter 1 three dimensional point set by a rhombic dodecahedron whose 
   opposite faces have distance 1, (which will ultimately be related to
   the three dimensional Borsuk's problem). We show that all these problems
   can be solved by analyzing the cohomology ring structure of certain
   simple moduli spaces, like $RP^n$ in the first problem and the space of
   3-dimensional cubes in the last two.