Time

May 7 2009 - 2:30pm - 3:30 pm

Location

MA240

Speaker

Andy Frohmader (Cornell)

Seminar Website

http://www.math.ohio-state.edu/~sgal/ggt/

Abstract

The Charney-Davis conjecture is an easy to state linear inequality on the face numbers of simplicial spheres (or more generally, homology spheres) that are also flag complexes, that is, complexes for which ever minimal
non-face is a two element set.  While the conjecture is reasonably well-known, it is only known to hold in a handful of rather narrow cases, and the proofs are often very complicated.  We will discuss some known results and give an easy proof of a relatively broad case.