Topology & Geometric Group Theory Seminar

Spring 2009

1:30 – 2:30, Malott 207

Tuesday, February 17

Pierre Py, University of Chicago

Quasi-morphisms and area-preserving homeomorphisms

I will recall the notion of a quasi-morphism on a group and describe a few examples of quasi-morphisms defined on groups of Hamiltonian diffeomorphisms of surfaces. Then we will try to answer the following question: which quasi-morphisms on these groups are continuous for the C0-topology? This question is related to the problem of the simplicity of the group of compactly supported area-preserving homeomorphisms of the disc. This is based on a joint work with M. Entov and L. Polterovich. This is also related to a recent work of Le Roux.

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