English

A dichotomy for topological full groups

Group Theory 2022-09-13 v3 Operator Algebras

Abstract

Given a minimal action α\alpha of a countable group on the Cantor set, we show that the alternating full group A(α)\mathsf{A}(\alpha) is non-amenable if and only if the topological full group F(α)\mathsf{F}(\alpha) is CC^*-simple. This implies, for instance, that the Elek-Monod example of non-amenable topological full group coming from a Cantor minimal Z2\mathbb{Z}^2-system is CC^*-simple.

Keywords

Cite

@article{arxiv.2111.13616,
  title  = {A dichotomy for topological full groups},
  author = {Eduardo Scarparo},
  journal= {arXiv preprint arXiv:2111.13616},
  year   = {2022}
}

Comments

6 pages. Fixed a couple of incorrections and added details to some of the proofs. Accepted in the Canadian Mathematical Bulletin

R2 v1 2026-06-24T07:53:20.521Z