## Topology Seminar (Introductory Talk): Classification of surface homeomorphisms and dilatations of pseudo-Anosov maps

Seminar | March 22 | 2:10-3 p.m. | 736 Evans Hall

Department of Mathematics

Thurston classified self-homeomorphisms of a topological surface up to isotopy as periodic, reducible, and pseudo-Anosov. pseudo-Anosov maps are the most interesting case in many respects and have a real invariant associated to them called the `dilatation'. I will describe the classification theorem and give a few properties of dilatations. Time permitting, I would like to talk about the somewhat related Thurston norm on the cohomology of 3-manifolds, and the Teichmüller polynomial.

hongbins@berkeley.edu