Almost-automorphisms of trees, cloning systems and finiteness properties
Abstract
We prove that the group of almost-automorphisms of the infinite rooted regular -ary tree arises naturally as the Thompson-like group of a so called -ary cloning system. A similar phenomenon occurs for any R\"over-Nekrashevych group , for a self-similar group. We use this framework to expand on work of Belk and Matucci, who proved that the R\"over group, using the Grigorchuk group for , is of type . Namely, we find some natural conditions on subgroups of to ensure that is of type , and in particular we prove this for all in the infinite family of \v{S}uni\'c groups. We also prove that if is itself of type then so is , and that every finitely generated virtually free group is self-similar, so in particular every finitely generated virtually free group yields a type R\"over-Nekrashevych group .
Keywords
Cite
@article{arxiv.1709.06524,
title = {Almost-automorphisms of trees, cloning systems and finiteness properties},
author = {Rachel Skipper and Matthew C. B. Zaremsky},
journal= {arXiv preprint arXiv:1709.06524},
year = {2021}
}
Comments
44 pages, 11 figures. v2: accepted version, published in J. Topol. Anal