English

Finiteness Properties of Locally Defined Groups

Group Theory 2020-10-19 v1

Abstract

Let XX be a set and let SS be an inverse semigroup of partial bijections of XX. Thus, an element of SS is a bijection between two subsets of XX, and the set SS is required to be closed under the operations of taking inverses and compositions of functions. We define ΓS\Gamma_{S} to be the set of self-bijections of XX in which each γΓS\gamma \in \Gamma_{S} is expressible as a union of finitely many members of SS. This set is a group with respect to composition. The groups ΓS\Gamma_{S} form a class containing numerous widely studied groups, such as Thompson's group VV, the Nekrashevych-R\"{o}ver groups, Houghton's groups, and the Brin-Thompson groups nVnV, among many others. We offer a unified construction of geometric models for ΓS\Gamma_{S} and a general framework for studying the finiteness properties of these groups.

Keywords

Cite

@article{arxiv.2010.08035,
  title  = {Finiteness Properties of Locally Defined Groups},
  author = {Daniel S. Farley and Bruce Hughes},
  journal= {arXiv preprint arXiv:2010.08035},
  year   = {2020}
}

Comments

61 pages, no figures

R2 v1 2026-06-23T19:23:20.102Z