English

Classifiability of crossed products by nonamenable groups

Operator Algebras 2023-03-01 v3 Dynamical Systems

Abstract

We show that all amenable, minimal actions of a large class of nonamenable countable groups on compact metric spaces have dynamical comparison. This class includes all nonamenable hyperbolic groups, many HNN-extensions, nonamenable Baumslag-Solitar groups, a large class of amalgamated free products, lattices in many Lie groups, A~2\widetilde{A}_2-groups, as well as direct products of the above with arbitrary countable groups. As a consequence, crossed products by amenable, minimal and topologically free actions of such groups on compact metric spaces are Kirchberg algebras in the UCT class, and are therefore classified by KK-theory.

Keywords

Cite

@article{arxiv.2201.03409,
  title  = {Classifiability of crossed products by nonamenable groups},
  author = {Eusebio Gardella and Shirly Geffen and Julian Kranz and Petr Naryshkin},
  journal= {arXiv preprint arXiv:2201.03409},
  year   = {2023}
}

Comments

v2: 30 pages, 1 figure. To appear in J. Reine Angew. Math. (Crelle)

R2 v1 2026-06-24T08:45:03.262Z