Special Topology Seminar: Something more to say about Dehn’s lemma

Seminar | October 16 | 4:10-5 p.m. | 732 Evans Hall | Canceled

 Michael Freedman, Microsoft Research

 Department of Mathematics

There seem to be 5 broad theorems whose conclusion is an embedded two dimensional disk (perhaps with additional structures). The five are about mapping a disk into manifolds of dimension: 2,3,4,higher, and symplectic manifolds, respectively. Each is worth knowing. The theorem about mapping a disk into a three manifold is called Dehn’s lemma. It is 60 years old, but I will explain a new wrinkle which is joint work with Marty Scharlemann.