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Caltech

Logic Seminar

Wednesday, October 12, 2022
11:00am to 12:00pm
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Online Event
Topological dynamics of kaleidoscopic groups
Todor Tsankov, Université Lyon 1,

Please note that the time is PST

Kaleidoscopic groups are infinite permutation groups recently introduced by Duchesne, Monod, and Wesolek by analogy with a classical construction of Burger and Mozes of subgroups of automorphism groups of regular trees. In contrast with the Burger-Mozes groups, kaleidoscopic groups are never locally compact and they are realized as groups of homeomorphisms of Wazewski dendrites (tree-like, compact spaces whose branch points are dense). The input for the construction is a finite or infinite permutation group Γ and the output is the kaleidoscopic group K(Γ).

In this talk, I will discuss recent joint work with Gianluca Basso, in which we explain how these groups can be viewed as automorphism groups of homogeneous structures and characterize the universal minimal flow of K(Γ) in terms of the original group Gamma.

For more information, please contact Math Dept. by phone at 626-395-4335 or by email at A. Kechris at [email protected].