Curve complexes and mapping class groups II

Series
Geometry Topology Working Seminar
Time
Friday, September 17, 2010 - 2:00pm for 2 hours
Location
Skiles 171
Speaker
Dan Margalit – Georgia Tech
Organizer
Dan Margalit
We will prove that the mapping class group is finitely presented, using its action on the arc complex. We will also use the curve complex to show that the abstract commensurator of the mapping class group is the extended mapping class group. If time allows, we will introduce the complex of minimizing cycles for a surface, and use it to compute the cohomological dimension of the Torelli subgroup of the mapping class group. This is a followup to the previous talk, but will be logically independent.