Seminars

23 September 2016 Ritsumeikan Geometry Seminar

2016.09.23 Fri up
Speaker: Gilbert Hector (University Lyon 1)
Title: Ends of graphs, finitely generated groups and group actions
Date: Friday 23 September 16:30-17:30
Place: Ritsumeikan University, Biwako-Kusatsu Campus West-Wing 7th floor 1st Laboratory of Mathematics
Abstract:
We will present a simple and quick proof of the following genericity
property for group actions first stated by Cantwell-Conlon:

Theorem. – Let G be a finitely generated group of homeomorphisms of a
compact space K. If all orbits of G are dense, there exists a residual
Baire set W of orbits such that
i) all orbits in W have the same endset E(W),
ii) E(W) is either a singleton, a pair of points or a Cantor set.

By the classical theorem of Hopf-Freudenthal the endset E(G) of G
verifies property ii) as well; so we will also discuss the possible
equality E(G) = E(W).
We will recall all concepts needed for the talk.

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