Intersection-saturated groups without free subgroups
Abstract
A group is said to be intersection-saturated if for every strictly positive integer and every map , one can find subgroups such that for every non-empty subset , the intersection is finitely generated if and only if . We obtain a new criterion for a group to be intersection-saturated based on the existence of arbitrarily high direct powers of a subgroup admitting an automorphism with a non-finitely generated set of fixed points. We use this criterion to find new examples of intersection-saturated groups, including Thompson's groups and the Grigorchuk group. In particular, this proves the existence of finitely presented intersection-saturated groups without non-abelian free subgroups, thus answering a question of Delgado, Roy and Ventura.
Cite
@article{arxiv.2312.09954,
title = {Intersection-saturated groups without free subgroups},
author = {Dominik Francoeur},
journal= {arXiv preprint arXiv:2312.09954},
year = {2023}
}
Comments
7 pages