English

On compact uniformly recurrent subgroups

Group Theory 2024-05-09 v2

Abstract

Let a group Γ\Gamma act on a paracompact, locally compact, Hausdorff space MM by homeomorphisms and let 2M2^M denote the set of closed subsets of MM. We endow 2M2^M with the Chabauty topology, which is compact and admits a natural Γ\Gamma-action by homeomorphisms. We show that for every minimal Γ\Gamma-invariant closed subset Y\mathcal Y of 2M2^M consisting of compact sets, the union YM\bigcup \mathcal{Y}\subset M has compact closure. As an application, we deduce that every compact uniformly recurrent subgroup of a locally compact group is contained in a compact normal subgroup. This generalizes a result of U\v{s}akov on compact subgroups whose normalizer is compact.

Keywords

Cite

@article{arxiv.2210.16297,
  title  = {On compact uniformly recurrent subgroups},
  author = {Pierre-Emmanuel Caprace and Gil Goffer and Waltraud Lederle and Todor Tsankov},
  journal= {arXiv preprint arXiv:2210.16297},
  year   = {2024}
}

Comments

Todor Tsankov added as author, statements generalized, proofs shortened. 10 pages

R2 v1 2026-06-28T04:44:15.517Z