Mathematics Department Colloquium: Different approaches to the virtual moduli cycle – an elementary introduction

Colloquium | April 12 | 4-5 p.m. | 60 Evans Hall

 Dusa McDuff, Barnard College

 Department of Mathematics

Most invariants of a symplectic manifold derive in some way from a count of J-holomorphic curves. However, in a general symplectic manifold one often cannot count curves directly in a robust way, i.e. so that the count is independent of the choice of perturbation. Instead one has to define a virtual count. This talk will try to give an elementary description of the problem and will describe some recent approaches to it.