[Binghamton Geometry Topology Seminar] Seminar This Week

[Matthew R Haulmark]

 Hi everyone,

This week our speaker will be Alexander Margolis from Vanderbilt
University. Here are the details.

*Title:*  Topological completions of quasi-actions and discretisable spaces

*Abstract: *A fundamental problem in geometric group theory is the study of
quasi-actions. We introduce and investigate discretisable spaces: spaces
for which every cobounded quasi-action can be quasi-conjugated to an
isometric action on a locally finite graph. Work of Mosher-Sageev-Whyte
shows that free groups are discretisable spaces, but the property holds
much more generally. For instance, most hyperbolic groups are
discretisable, as are most finitely presented groups of cohomological
dimension two.

Along the way, we introduce the concept of the topological completion of a
quasi-action. This is a locally compact group, well-defined up to a compact
normal subgroup, reflecting the geometry of the quasi-action. We give
several applications of the tools we develop. For instance, we show that
any finitely generated group quasi-isometric to a ‬Z‭-by-hyperbolic group
is also Z-by-hyperbolic.


Zoom link for the seminar, 2:50 - 3:50:
https://binghamton.zoom.us/j/94057178271

Zoom link for the coffee, 12:30 - 1:30:
https://binghamton.zoom.us/j/96674397432

Best,

Matt
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