Max Dehn Seminar
on Geometry, Topology, Dynamics, and Groups
Spring 2013
Date  Speaker  Title — click for abstract (if available) 
February 20 
Ken Bromberg University of Utah 
Stable commutator length on mapping class groups
We will discuss stable commutator length on mapping class groups.

February 27 
Laura DeMarco University of Illinois, Chicago 
Degenerations of complex dynamical systems
Given a family of rational maps or polynomials, a basic problem is to understand
what happens (dynamically) as the family degenerates. In this talk, I will describe
a limiting object as a "nonarchimedean dynamical system" in terms of a rational
function acting on a Berkovich space. In geometric terms, this is a dynamical
system on an Rtree.

March 27 
Kevin Wortman University of Utah 
TBA
TBA

April 3 
Sam Taylor University of Texas 
Convex cocompactness in Mod(S) via quasiconvexity in RAAGs
We will characterize convex cocompact subgroups of mapping class groups that arise as subgroups of specially embedded rightangled Artin groups. With this characterization, we construct convex cocompact subgroups of Mod(S) with "small translation length" on the curve complex. This is joint work with Johanna Mangahas.

April 24 
Daniel Studenmund University of Chicago 
Abstract commensurators of lattices in Lie groups
The abstract commensurator of a group G is the group of all isomorphisms between finite index subgroups of G up to a natural equivalence relation. Commensurators of lattices in semisimple Lie groups are well understood, using strong rigidity results of Mostow, Prasad, and Margulis. We will describe commensurators of lattices in solvable groups, where strong rigidity fails. If time permits, we will extend these results to lattices in certain groups that are neither solvable nor semisimple.

Current seminar Archive of past talks
Max Dehn Seminar is organized by Mladen Bestvina, Ken Bromberg, Patrick Reynolds,
Jing Tao, Domingo Toledo, and Kevin Wortman.
This web page is maintained by Patrick Reynolds and Jing Tao.