English

Simplicity of action-based $C^{*}$-algebras from hyperbolic actions

Operator Algebras 2026-05-04 v2 Group Theory

Abstract

We study the simplicity of CC^{*}-algebras built from group actions. For a faithful isometric action of a group GG on a countable metric space XX, we use the associated action representation on 2(X)\ell^2(X) to define the action-based CC^{*}-algebra CXGC^{*}_{X}G. We define generalized versions of the properties PnaiveP_{\text{naive}} and PanalyticP_{\text{analytic}} relative to the action and show that the naive form implies the analytic form. We also prove that the properties PanalyticP_{\text{analytic}} associated with a continuous action ensure the simplicity of the action-based CC^*-algebra. As an application, we deduce that big mapping class groups satisfy the property PnaiveXP_{\text{naive}}^{\mathbb{X}} and the associated action-based CC^*-algebra is simple.

Keywords

Cite

@article{arxiv.2604.12520,
  title  = {Simplicity of action-based $C^{*}$-algebras from hyperbolic actions},
  author = {Tianyi Lou},
  journal= {arXiv preprint arXiv:2604.12520},
  year   = {2026}
}

Comments

20 pages

R2 v1 2026-07-01T12:08:25.938Z