Max Dehn Seminar

on Geometry, Topology, Dynamics, and Groups

Spring 2019 3:15-4:15 JWB 308

Date Speaker Title click for abstract (if available)
October 4 10:45-11:45 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 Bou-Rabee.
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, finite-type surface of genus at least 3 is perfect, that is, it has trivial abelianization. We will discuss how this fails for infinite-genus surfaces and give a complete characterization of all homomorphisms from pure mapping class groups of infinite-genus 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
March 27
John Griesmer
Colorado School of Mines
February 27
Sebastian Hensel
Mathematics Institute, University of Munich

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You may also be interested in the RTG Seminar
Max Dehn Seminar is organized by Mladen Bestvina, Ken Bromberg, Jon Chaika,
Donald Robertson, Domingo Toledo, and Kevin Wortman.

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