Geometry/Topology Seminar
Spring 2018
Thursdays (and sometimes Tuesdays) 3-4pm, in
Ryerson 358
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- Thursday October 11 at 3-4pm in Ry 358
- Rita Gitik, University of Michigan
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On Tame Subgroups of Finitely Presented Groups
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Abstract: We describe several examples of tame
subgroups of finitely presented groups and prove that the
fundamental groups of certain finite graphs of groups are
locally tame.
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- Thursday October 18 at 3-4pm in Ry 358
- Daniel Ramras, IUPUI
- Homological stability for spaces of representations
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Abstract: I will discuss recent work with Mentor
Stafa on homological stability for various spaces built from
commuting elements in Lie groups. These results depend on
rational models for these spaces due to T. Baird, and
utilize J. Wilson's theory of FIW-modules. A key
aspect of this work is the relationship between stability in
ordinary and in equivariant (co)homology. Time permitting,
I'll also discuss what is known regarding stability for
character varieties of free groups and surface groups.
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- Thursday October 25 at 3-4pm in Ry 358
- Daniel Studenmund, Notre Dame
- Commensurability growth of nilpotent groups
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Abstract: 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, associated to a subgroup Gamma in an ambient group
G. The main result of this talk concerns 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.
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- Thursday November 01 at 3-4pm in Ry 358
- Yulan Qing, University of Toronto
- Loops with Large Twist Get Short Along Quasi-geodesics in Out(Fn)
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Abstract: We study the behaviour of quasi-geodesics
in Out(Fn) equipped with word metric. Given an element
\phi of Out(Fn), there are several natural paths
connecting the origin to \phi in Out(Fn). We show
that these paths are, in general, not quasi-geodesics in
Out(Fn). In fact, we clear up the current misunderstanding
about distance estimating in Out(Fn) by showing that there
exists points in Out(Fn) where all quasi-geodesics between
them backtracks in all of the current Out(Fn) complexes .
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- Thursday November 08 at 3-4pm in Ry 358
- Kevin Schreve, University of Chicago
- TBA
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Abstract: TBA
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- Thursday November 15 at 3-4pm in Ry 358
- Trevor Hyde, University of Michigan
- TBA
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Abstract: TBA
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- Thursday November 29 at 3-4pm in Ry 358
- Kasia Jankiewicz, University of Chicago
- TBA
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Abstract: TBA
Due to the high number of requests, we are no longer accepting speakers via self-invitations.
For questions, contact