English

Generating infinite monoids of cellular automata

Group Theory 2023-01-27 v2 Dynamical Systems

Abstract

For a group GG and a set AA, let End(AG)\text{End}(A^G) be the monoid of all cellular automata over AGA^G, and let Aut(AG)\text{Aut}(A^G) be its group of units. By establishing a characterisation of surjunctuve groups in terms of the monoid End(AG)\text{End}(A^G), we prove that the rank of End(AG)\text{End}(A^G) (i.e. the smallest cardinality of a generating set) is equal to the rank of Aut(AG)\text{Aut}(A^G) plus the relative rank of Aut(AG)\text{Aut}(A^G) in End(AG)\text{End}(A^G), and that the latter is infinite when GG has an infinite decreasing chain of normal subgroups of finite index, condition which is satisfied, for example, for any infinite residually finite group. Moreover, when A=VA=V is a vector space over a field F\mathbb{F}, we study the monoid EndF(VG)\text{End}_{\mathbb{F}}(V^G) of all linear cellular automata over VGV^G and its group of units AutF(VG)\text{Aut}_{\mathbb{F}}(V^G). We show that if GG is an indicable group and VV is finite-dimensional, then EndF(VG)\text{End}_{\mathbb{F}}(V^G) is not finitely generated; however, for any finitely generated indicable group GG, the group AutF(FG)\text{Aut}_{\mathbb{F}}(\mathbb{F}^G) is finitely generated if and only if F\mathbb{F} is finite.

Keywords

Cite

@article{arxiv.2004.07321,
  title  = {Generating infinite monoids of cellular automata},
  author = {Alonso Castillo-Ramirez},
  journal= {arXiv preprint arXiv:2004.07321},
  year   = {2023}
}

Comments

11 pages

R2 v1 2026-06-23T14:52:54.700Z