Speaker: Graeme Wilkin

Title: Morse theory and the cohomology of quiver varieties.

Abstract: This talk will be largely expository, explaining some of the ideas behind Nakajima's topological construction of representations of Kac-Moody algebras on the cohomology of quiver varieties. In the last twenty minutes I will describe a Morse-theoretic approach to computing cohomological invariants of quiver varieties, which is joint work in progress with Megumi Harada. We have derived conjectural formulae for the Betti numbers of some simple quiver varieties and our derivation turns out to share some features with the Nakajima picture, leading to many interesting questions.