Monster groups acting on CAT(0) spaces
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| Description: |
Coulon, R (Université de Rennes 1, CNRS (Centre national de la recherche scientifique))
Thursday 16th February 2017 - 10:00 to 12:00 |
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| Created: | 2017-03-14 10:55 |
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| Collection: | Non-Positive Curvature Group Actions and Cohomology |
| Publisher: | Isaac Newton Institute |
| Copyright: | Coulon, R |
| Language: | eng (English) |
| Distribution: |
World
(downloadable)
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| Explicit content: | No |
| Aspect Ratio: | 16:9 |
| Screencast: | No |
| Bumper: | UCS Default |
| Trailer: | UCS Default |
| Abstract: | Since the beginning of the 20th century, infinite torsion groups have been the source of numerous developments in group theory: Burnside groups Tarski monsters, Grigorchuck groups, etc. From a geometric point of view, one would like to understand on which metric spaces such groups may act in a non degenerated way (e.g. without a global fixed point). In this talk we will focus on CAT(0) spaces and present two examples with rather curious properties. The first one is a non-amenable finitely generated torsion group acting properly on a CAT(0) cube complex. The second one is a non-abelian finitely generated Tarski-like monster : every finitely generated subgroup is either finite or has finite index. In addition this group is residually finite and does not have Kazdhan property (T). (Joint work with Vincent Guirardel) |
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