Max Dehn Seminar
on Geometry, Topology, Dynamics, and Groups
Spring 2019 3:154:15 JWB 308
Date  Speaker  Title click for abstract (if available) 
October 4 10:4511:45 in JWB 240

Daniel Studenmund
Notre Dame 
Commensurability growth of nilpotent groups
A classical area of study in geometric group theory is subgroup growth,
which counts the number of subgroups of a given group Gamma as a
function their index. We will study a richer function, the
commensurability growth, which is a function associated to a subgroup
Gamma in an ambient group G. This talk covers the case that Gamma is an
arithmetic subgroup of a unipotent group G, starting with the simplest
example of the integers in the real line. This is joint work with Khalid
BouRabee.

December 14 at 3:15 in LCB 219

Priyam Patel
University of California, Santa Barbara 
Homomorphisms of pure mapping class groups to the
integers
A classical theorem of Powell (with roots in the work of Mumford and
Birman) states that the pure mapping class group of a connected,
orientable, finitetype surface of genus at least 3 is perfect, that is,
it has trivial abelianization. We will discuss how this fails for
infinitegenus surfaces and give a complete characterization of all
homomorphisms from pure mapping class groups of infinitegenus surfaces
to the integers. This is joint work with Javier Aramayona and Nicholas
Vlamis.

January 16

Jing Tao
University of Oklahoma 
Big Torelli Groups
I will discuss some joint work with Aramayona, Ghaswala, Kent, McLeay,
and Winarski on the Torelli subgroup of big mapping class groups.

January 23

James Farre
University of Utah 
TBA
TBA

March 27

John Griesmer
Colorado School of Mines 
TBA
TBA

February 27

Sebastian Hensel
Mathematics Institute, University of Munich 
TBA
TBA

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