More on wreath products of cellular automata
Abstract
We prove that if a subgroup of the automorphism group of a non-trivial full shift acts on points of finite support with a free orbit, then for every finitely-generated abelian group , the abstract group also embeds in . The groups admitting an action with such a free orbit include for a finite abelian group, and finitely-generated free groups. The class of such groups is also closed under commensurability and direct products. We obtain for example that , and embed in . To our knowledge, the group is the first example of a finitely-generated torsion-free subgroup of with infinite cohomological dimension. It answers an implicit question of Kim and Roush and an explicit question of the author. We also explore a simpler variant of the construction that gives some near-misses to iterated permutational wreath products, as well as some Neumann groups.
Keywords
Cite
@article{arxiv.2305.17946,
title = {More on wreath products of cellular automata},
author = {Ville Salo},
journal= {arXiv preprint arXiv:2305.17946},
year = {2023}
}
Comments
18 pages, 2 figures