Columbia Geometric Topology Seminar

Spring 2017

The GT seminar meets on Fridays in Math 520, at 2 PM (overflow seminars Thursday 2:40pm Room 507).
Organizer: Walter Neumann.
Other area seminars. Our e-mail list. Archive of previous semesters

Date Speaker Title
January 20 Organizational Meeting Room 520, 2pm
February 3 Victoria Akin, Chicago Point-pushing in the mapping class group
February 10 Jonah Gaster, Boston College TBA
February 17 Sarah Mousley, U. Illinois TBA
February 24 Carolyn Abbott, CUNY and Wisconsin Universal acylindrical actions
March 3 Feng Luo, Rutgers TBA
March 10 Anh Tran, UT Dallas TBA
March 17 No seminar Spring break
March 24 Xinghua Gao, Illinois TBA
March 31 Ilya Kofman, CUNY TBA
April 7 Matthew Stover TBA
April 14 TBA TBA
April 21 Kevin Kordek, TAMU TBA
April 28 TBA TBA



Victoria Akin, Chicago
February 3
Title: Point-pushing in the mapping class group
The point-pushing subgroup of the mapping class group of a surface with a marked point can be considered topologically as the subgroup that pushes the marked point about loops in the surface. Birman, who discovered the point-pushing map, showed that this subgroup is abstractly isomorphic to the fundamental group of the surface, \pi_1(S). We can characterize this point-pushing subgroup algebraically as the only normal subgroup inside of the mapping class group isomorphic to \pi_1(S). This uniqueness allows us to recover a description of the outer automorphism group of the mapping class group.

Jonah Gaster, Boston College
February 10

Sarah Mousley, U. Illinois
February 17

Carolyn Abbott, CUNY and Wisconsin
February 24
Title:Universal acylindrical actions
The class of acylindrically hyperbolic groups, which are groups that admit a certain type of non-elementary action on a hyperbolic space, contains many interesting groups such as non-exceptional mapping class groups and Out(F_n) for n>1. In such a group, a generalized loxodromic element is one that is loxodromic for some acylindrical action of the group on a hyperbolic space. Given a finitely generated group, one can look for an acylindrical action on a hyperbolic space in which all generalized loxodromic elements act loxodromically; such an action is called a universal acylindrical action. I will discuss recent results in the search for universal acylindrical actions, describing a class of groups for which it is always possible to construct such an action as well as an example of a group for which no such action exists.

Feng Luo, Rutgers
March 3

Ahn Tran, UT Dallas
March 10

Xinghua Gao, Illinois
March 24

Ilya Kofman, CUNY
March 31

Matthew Stover, Temple
April 7

Kevin Kordek, TAMU
April 21

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Previous semesters:

Fall 2016, Spring 2016, Fall 2015, Spring 2015, Fall 2014, Spring 2014, Fall 2013, Spring 2013, Fall 2012, Spring 2012, Fall 2011, 2010/11, Spring 2010, Fall 2009, Spring 2009, Fall 2008, Spring 2008, Fall 2007, Spring 2007, Fall 2006.

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