English

Self-simulable groups

Group Theory 2025-02-25 v4 Dynamical Systems

Abstract

We say that a finitely generated group Γ\Gamma is self-simulable if every effectively closed action of Γ\Gamma on a closed subset of {0,1}N\{\texttt{0},\texttt{1}\}^{\mathbb{N}} is the topological factor of a Γ\Gamma-subshift of finite type. We show that self-simulable groups exist, that any direct product of non-amenable finitely generated groups is self-simulable, that under technical conditions self-simulability is inherited from subgroups, and that the subclass of self-simulable groups is stable under commensurability and quasi-isometries of finitely presented groups. Some notable examples of self-simulable groups obtained are the direct product Fk×FkF_k \times F_k of two free groups of rank k2k \geq 2, non-amenable finitely generated branch groups, the simple groups of Burger and Mozes, Thompson's VV, the groups GLn(Z)\operatorname{GL}_n(\mathbb{Z}), SLn(Z)\operatorname{SL}_n(\mathbb{Z}), Aut(Fn)\operatorname{Aut}(F_n) and Out(Fn)\operatorname{Out}(F_n) for n5n \geq 5; The braid groups BmB_m for m7m \geq 7, and certain classes of RAAGs. We also show that Thompson's FF is self-simulable if and only if FF is non-amenable, thus giving a computability characterization of this well-known open problem. We also exhibit a few applications of self-simulability on the dynamics of these groups, notably, that every self-simulable group with decidable word problem admits a nonempty strongly aperiodic subshift of finite type.

Keywords

Cite

@article{arxiv.2104.05141,
  title  = {Self-simulable groups},
  author = {Sebastián Barbieri and Mathieu Sablik and Ville Salo},
  journal= {arXiv preprint arXiv:2104.05141},
  year   = {2025}
}

Comments

Simplified since last version. We also modified the title