Sofic actions on graphs

Fuente: arXiv
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Auteurs principaux: Gao, David, Patchell, Greg, Elayavalli, Srivatsav Kunnawalkam
Format: Preprint
Publié: 2024
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author Gao, David
Patchell, Greg
Elayavalli, Srivatsav Kunnawalkam
author_facet Gao, David
Patchell, Greg
Elayavalli, Srivatsav Kunnawalkam
contents We develop a theory of soficity for actions on graphs and obtain new applications to the study of sofic groups. We establish various examples, stability and permanence properties of sofic actions on graphs, in particular soficity is preserved by taking several natural graph join operations. We prove that an action of a group on its Cayley graph is sofic if and only if the group is sofic. We show that arbitrary actions of amenable groups on graphs are sofic. Using a graph theoretic result of E. Hrushovski, we also show that arbitrary actions of free groups on graphs are sofic. Notably we show that arbitrary actions of sofic groups on graphs, with amenable stabilizers, are sofic, settling completely an open problem from \cite{gao2024soficity}. We also show that soficity is preserved by taking limits under a natural Gromov-Hausdorff topology, generalizing prior work of the first author \cite{gao2024actionslerfgroupssets}. Our work sheds light on a family of groups called graph wreath products, simultaneously generalizing graph products and generalized wreath products. Extending various prior results in this direction including soficity of generalized wreath products \cite{gao2024soficity}, B. Hayes and A. Sale \cite{HayesSale}, and soficity of graph products \cite{CHR, charlesworth2021matrix}, we show that graph wreath products are sofic if the action and acting groups are sofic. These results provide several new examples of sofic groups in a systematic manner.
format Preprint
id arxiv_https___arxiv_org_abs_2408_15470
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sofic actions on graphs
Gao, David
Patchell, Greg
Elayavalli, Srivatsav Kunnawalkam
Group Theory
Operator Algebras
We develop a theory of soficity for actions on graphs and obtain new applications to the study of sofic groups. We establish various examples, stability and permanence properties of sofic actions on graphs, in particular soficity is preserved by taking several natural graph join operations. We prove that an action of a group on its Cayley graph is sofic if and only if the group is sofic. We show that arbitrary actions of amenable groups on graphs are sofic. Using a graph theoretic result of E. Hrushovski, we also show that arbitrary actions of free groups on graphs are sofic. Notably we show that arbitrary actions of sofic groups on graphs, with amenable stabilizers, are sofic, settling completely an open problem from \cite{gao2024soficity}. We also show that soficity is preserved by taking limits under a natural Gromov-Hausdorff topology, generalizing prior work of the first author \cite{gao2024actionslerfgroupssets}. Our work sheds light on a family of groups called graph wreath products, simultaneously generalizing graph products and generalized wreath products. Extending various prior results in this direction including soficity of generalized wreath products \cite{gao2024soficity}, B. Hayes and A. Sale \cite{HayesSale}, and soficity of graph products \cite{CHR, charlesworth2021matrix}, we show that graph wreath products are sofic if the action and acting groups are sofic. These results provide several new examples of sofic groups in a systematic manner.
title Sofic actions on graphs
topic Group Theory
Operator Algebras
url https://arxiv.org/abs/2408.15470