English

Amenability and profinite completions of finitely generated groups

Group Theory 2021-06-17 v1

Abstract

This article explores the interplay between the finite quotients of finitely generated residually finite groups and the concept of amenability. We construct a finitely generated, residually finite, amenable group AA and an uncountable family of finitely generated, residually finite non-amenable groups all of which are profinitely isomorphic to AA. All of these groups are branch groups. Moreover, picking up Grothendieck's problem, the group AA embeds in these groups such that the inclusion induces an isomorphism of profinite completions. In addition, we review the concept of uniform amenability, a strengthening of amenability introduced in the 70's, and we prove that uniform amenability indeed is detectable from the profinite completion.

Keywords

Cite

@article{arxiv.2106.08742,
  title  = {Amenability and profinite completions of finitely generated groups},
  author = {Steffen Kionke and Eduard Schesler},
  journal= {arXiv preprint arXiv:2106.08742},
  year   = {2021}
}

Comments

19 pages. Comments welcome!