{ "id": "1901.02808", "version": "v1", "published": "2019-01-09T16:27:31.000Z", "updated": "2019-01-09T16:27:31.000Z", "title": "Bounding the minimal number of generators of groups of cellular automata", "authors": [ "Alonso Castillo-Ramirez", "Miguel Sanchez-Alvarez" ], "comment": "12 pages", "categories": [ "math.GR", "cs.FL" ], "abstract": "For a group $G$ and a finite set $A$, denote by $\\text{ICA}(G;A)$ the group of all invertible cellular automata over $A^G$. We study the minimal cardinality of a generating set, known as the rank, of $\\text{ICA}(G;A)$. In the first part, when $G$ is a finite group, we give upper bounds for the rank in terms of the number of conjugacy classes of subgroups of $G$. The case when $G$ is a finite cyclic group has been studied before, so here we focus on the cases when $G$ is a finite dihedral group or a finite Dedekind group. In the second part, we find a basic lower bound for the rank of $\\text{ICA}(G;A)$ when $G$ is a finite group, and we apply this to show that, for any infinite abelian group $H$, the group $\\text{ICA}(H;A)$ is not finitely generated. The same is true for various kinds of infinite groups, so we ask if there exists an infinite group $H$ such that $\\text{ICA}(H;A)$ is finitely generated.", "revisions": [ { "version": "v1", "updated": "2019-01-09T16:27:31.000Z" } ], "analyses": { "subjects": [ "68Q80", "05E18", "20M20" ], "keywords": [ "cellular automata", "minimal number", "generators", "infinite group", "infinite abelian group" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable" } } }