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Hauptverfasser: Izeki, Hiroyasu, Karlsson, Anders
Format: Preprint
Veröffentlicht: 2024
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Online-Zugang:https://arxiv.org/abs/2404.19273
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author Izeki, Hiroyasu
Karlsson, Anders
author_facet Izeki, Hiroyasu
Karlsson, Anders
contents We show that finitely generated groups which are Liouville and without infinite finite-dimensional linear representations must have a global fixed point whenever they act by isometry on a finite-dimensional complete CAT(0)-space. This provides a partial answer to an old question in geometric group theory and proves partly a conjecture formulated by Norin, Osajda, and Przytycki. It applies in particular to Grigorchuk's groups of intermediate growth and other branch groups as well as to simple groups with the Liouville property such as those found by Matte Bon and by Nekrashevych. The method of proof uses ultralimits, equivariant harmonic maps, subharmonic functions, horofunctions and random walks.
format Preprint
id arxiv_https___arxiv_org_abs_2404_19273
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Torsion groups of subexponential growth cannot act on finite-dimensional CAT(0)-spaces without a fixed point
Izeki, Hiroyasu
Karlsson, Anders
Group Theory
20F65, 20K10, 58E20
We show that finitely generated groups which are Liouville and without infinite finite-dimensional linear representations must have a global fixed point whenever they act by isometry on a finite-dimensional complete CAT(0)-space. This provides a partial answer to an old question in geometric group theory and proves partly a conjecture formulated by Norin, Osajda, and Przytycki. It applies in particular to Grigorchuk's groups of intermediate growth and other branch groups as well as to simple groups with the Liouville property such as those found by Matte Bon and by Nekrashevych. The method of proof uses ultralimits, equivariant harmonic maps, subharmonic functions, horofunctions and random walks.
title Torsion groups of subexponential growth cannot act on finite-dimensional CAT(0)-spaces without a fixed point
topic Group Theory
20F65, 20K10, 58E20
url https://arxiv.org/abs/2404.19273