Virtualconference
H Quasi-actions and almost normal subgroups
Auteurs : Margolis, Alex (Auteur de la Conférence)
CIRM (Editeur )
CIRM (Editeur )
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Automorphism groups of Coxeter groups do not have Kazhdan's property (T)
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Right-angled Coxeter groups commensurable to right-angled Artin groups
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Complexes of parabolic subgroups for Artin groups
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- KAPOVICH, Michael, KLEINER, Bruce, et LEEB, Bernhard. Quasi-isometries and the de Rham decomposition. Topology, 1998, vol. 37, no 6, p. 1193-1211. - https://doi.org/10.1016/S0040-9383(97)00091-8
- MOSHER, Lee, SAGEEV, Michah, et WHYTE, Kevin. Quasi-actions on trees I. Bounded valence. Annals of mathematics, 2003, p. 115-164. - https://www.jstor.org/stable/3597155
- MARGOLIS, Alexander. The geometry of groups containing almost normal subgroups. arXiv preprint arXiv:1905.03062, 2019. - https://arxiv.org/abs/1905.03062
- MARGOLIS, Alexander. Discretisable quasi-actions. in preparation (2020) -
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Résumé :
If a group G acts isometrically on a metric space X and Y is any metric space that is quasi-isometric to X, then G quasi-acts on Y. A fundamental problem in geometric group theory is to straighten (or quasi-conjugate) a quasi-action to an isometric action on a nice space. We will introduce and investigate discretisable spaces, those for which every cobounded quasi-action can be quasi-conjugated to an isometric action of a locally finite graph. Work of Mosher-Sageev-Whyte shows that free groups have this property, but it holds much more generally. For instance, we show that every hyperbolic group is either commensurable to a cocompact lattice in rank one Lie group, or it is discretisable.
We give several applications and indicate possible future directions of this ongoing work, particularly in showing that normal and almost normal subgroups are often preserved by quasi-isometries. For instance, we show that any finitely generated group quasi-isometric to a Z-by-hyperbolic group is Z-by-hyperbolic. We also show that within the class of residually finite groups, the class of central extensions of finitely generated abelian groups by hyperbolic groups is closed under quasi-isometries.
We give several applications and indicate possible future directions of this ongoing work, particularly in showing that normal and almost normal subgroups are often preserved by quasi-isometries. For instance, we show that any finitely generated group quasi-isometric to a Z-by-hyperbolic group is Z-by-hyperbolic. We also show that within the class of residually finite groups, the class of central extensions of finitely generated abelian groups by hyperbolic groups is closed under quasi-isometries.
Keywords : Quasi-action; quasi-isometry; almost normal; hyperbolic
Codes MSC :
20E08
- Groups acting on trees
20F65
- Geometric group theory
20J05
- Homological methods in group theory
57M07
- Topological methods in group theory
Ressources complémentaires :
https://conferences.cirm-math.fr/uploads/1/6/6/4/16648158/pres.pdf
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Informations sur la Vidéo
Réalisateur : Hennenfent, GuillaumeLangue : Anglais Date de publication : 01/06/2020 Date de captation : 27/05/2020 Collection : Research talks ; Geometry ; Topology Durée : 00:33:48 Domaine : Geometry ; Topology Audience : Chercheurs ; Doctorants , Post - Doctorants ; Grand Public Download : https://videos.cirm-math.fr/2020-05-27_Margolis.mp4 
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Informations sur la Rencontre Virtuelle
Nom de la rencontre : Virtual Geometric Group Theory conference / Rencontre virtuelle en géométrie des groupesOrganisateurs de la rencontre : Chatterji, Indira ; Paris, Luis ; Vogtmann, Karen Dates : 01/06/2020 - 05/06/2020 Année de la rencontre : 2020 URL Congrès : https://conferences.cirm-math.fr/virtual...
Citation Data
DOI : 10.24350/CIRM.V.19636503Cite this video as: Margolis, Alex (2020). Quasi-actions and almost normal subgroups.CIRM . Audiovisual resource. doi:10.24350/CIRM.V.19636503 URI : http://dx.doi.org/10.24350/CIRM.V.19636503 |
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