English

Proper actions of Grigorchuk groups on a CAT(0) cube complex

Group Theory 2024-10-29 v2

Abstract

On this paper we will present a construction of a CAT(0) cube complex (an infinite cube), on which the uncountable family of Grigorchuk groups GωG_\omega act without bounded orbit. Moreover, if the sequence ω\omega does not contain repetition, we prove that the action is proper and faithful. As a consequence of this result, this cube complex is a model for the classifying space of proper actions for all the groups GωG_\omega with ω\omega without repetition. This construction works in a general way for any group acting on a set and which admits a commensurated subset.These examples of non-elliptic actions of infinite finitely generated torsion groups on a non-positively curved cube complex contrast to several established fixed-point theorems concerning actions of torsion groups.

Keywords

Cite

@article{arxiv.2207.04980,
  title  = {Proper actions of Grigorchuk groups on a CAT(0) cube complex},
  author = {Grégoire Schneeberger},
  journal= {arXiv preprint arXiv:2207.04980},
  year   = {2024}
}
R2 v1 2026-06-25T00:49:07.207Z