CoSP ZOOM Seminar on topological combinatorics

This summer Shira Zerbib is coordinating a CoSP Zoom seminar on topological combinatorics, replacing a conference on the same topic that was supposed to take place in Prague this summer and was cancelled due to COVID-19. 

The talks will be given on Tuesdays and Thursdays at 8:00am (CDT), as of June 30, 2020. 


6/30 - Andeas Holmsen (KAIST)

Title: The Fractional Helly property and topological complexity

Abstract: The fractional Helly theorem is a simple yet remarkable generalization of Helly’s classical theorem on the intersection of convex sets, and it is of considerable interest to extend the fractional Helly theorem beyond the setting of convexity. In this talk I will discuss a recent result which shows that the fractional Helly theorem holds for families of subsets of R^d which satisfy only very weak topological assumptions. This is joint work with Xavier Goaoc and Zuzana Patáková.

7/2 - Florian Frick (Carnegie Mellon University)

Title: The topological Tverberg problem beyond prime powers

Abstract: Given d and q the topological Tverberg problem asks for the minimal n such that any continuous map from the n-dimensional simplex to R^d identifies q points from pairwise disjoint faces. For q a prime power n is (q-1)(d+1). The lower bound follows from a general position argument, the upper bound from equivariant topological methods. It was shown recently that for q with at least two distinct prime divisors the lower bound may be improved. For those q non-trivial upper bounds had been elusive. I will show that n is at most q(d+1)-1 for all q. I had previously conjectured this to be optimal unless q is a prime power. This is joint work with Pablo Soberón.

7/7 - Minki Kim (Technion)

7/9 - Zilin Jiang (MIT)

7/14 - Gabor Simonyi (Renyi Institute)

7/16 - Jinha Kim (Technion)

7/21 - Tomas Kaiser (University of West Bohemia) & Matej Stehlik (Universite Grenoble Alpes) - double talk

7/23 - Amzi Jeffs (University of Washington)

7/28 - Martin Loebl (Charles University)

7/30 - Pablo Soberon (Baruch College)