English

Almost automorphic systems have invariant measures

Dynamical Systems 2023-12-27 v2 Group Theory

Abstract

Let GG be a non-amenable countable group. We show that every almost automorphic GG-action on a compact Hausdorff space, with a maximal equicontinuous factor whose phase space is a Cantor set, admits invariant probability measures (this partially answers a question posed by Veech). In particular, every Toeplitz GG-subshift has a non-empty space of invariant measures, meaning that this family of subshifts is not a test for amenability for countable groups. We prove that almost one-to-one extensions without measures ensure the existence of symbolic almost one-to-one extensions with equal characteristics. As a consequence, we obtain the most general result of this paper. Finally, as a corollary of our results, we deduce that the class of Toeplitz subshifts is not dense in the space of infinite transitive subshifts of ΣG\Sigma^G, unlike G=ZG=\mathbb{Z}.

Keywords

Cite

@article{arxiv.2312.12562,
  title  = {Almost automorphic systems have invariant measures},
  author = {María Isabel Cortez and Jaime Gómez},
  journal= {arXiv preprint arXiv:2312.12562},
  year   = {2023}
}

Comments

There is an error in theorem 14, which we believe cannot be corrected. We are working on a new version of this topic, which may take a little longer

R2 v1 2026-06-28T13:56:48.434Z