Local testability in group theory II

54 mins 9 secs,  99.07 MB,  MP3  44100 Hz,  249.78 kbits/sec
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Description: Becker, O (Hebrew University of Jerusalem)
Tuesday 9th May 2017 - 10:00 to 11:00
 
Created: 2017-05-10 15:40
Collection: Non-Positive Curvature Group Actions and Cohomology
Publisher: Isaac Newton Institute
Copyright: Becker, O
Language: eng (English)
Distribution: World     (downloadable)
Explicit content: No
Aspect Ratio: 16:9
Screencast: No
Bumper: UCS Default
Trailer: UCS Default
 
Abstract: This talk is a continuation of Alex Lubotzky's talk with a similar title (but an effort will be made to keep it independent).
We will describe a combinatorial/geometric method to prove testability (or non-testability) in various cases.
For certain amenable groups, we present a method of "tiling" every Schreier graph by finite Schreier graphs. This is an extension of the work of Weiss on monotileable groups. We then use the tilings to prove testability for those groups by a method which has its origins in the work of Ornstein-Weiss on amenable groups. This enables us to answer some questions posed in a paper by Arzhantseva and Paunescu and extend some of their results. It also suggests many more questions for further research.
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