UW Combinatorics Talk

UW Combinatorics Seminar

Title: The polynomial Hirsch conjecture is true for flag complexes

Bruno Benedetti

Royal Institute of Technology (KTH)

October 10, 4:00pm
Padelford C-401

refreshments at 3:30pm
Pre-Seminar at 2:30pm in Padelford C-401

ABSTRACT 

Two years ago, here in Seattle, Santos communicated his negative solution of the Hirsch conjecture. (The conjecture was, "in any d-polytope with n facets, any two vertices are connected by a path of at most n-d edges".) However, the Polynomial Hirsch Conjecture ("...at most P(n,d) edges, for a polynomial P that does not depend on the polytope") is still wide open. Here we present some recent progress. We show that the Polynomial Hirsch Conjecture is true for flag complexes; and more generally, for all simplicial complexes whose Stanley-Reisner ideal is generated in bounded degree. In particular, we show that every flag manifold is Hirsch. This extends a classical result by Provan and Billera ("the barycentric subdivision of every shellable sphere is Hirsch"). This is joint work with Karim Adiprasito.


Speaker's Contact Info: http://www.math.kth.se/~brunoben/


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Sara Billey, Combinatorics Seminar, Mathematics Department, University of Washington,

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