English

Simple groups separated by finiteness properties

Group Theory 2018-10-23 v3

Abstract

We show that for every positive integer nn there exists a simple group that is of type Fn1\mathrm{F}_{n-1} but not of type Fn\mathrm{F}_n. For n3n\ge 3 these groups are the first known examples of this kind. They also provide infinitely many quasi-isometry classes of finitely presented simple groups. The only previously known infinite family of such classes, due to Caprace--R\'emy, consists of non-affine Kac--Moody groups over finite fields. Our examples arise from R\"over--Nekrashevych groups, and contain free abelian groups of infinite rank.

Keywords

Cite

@article{arxiv.1712.05361,
  title  = {Simple groups separated by finiteness properties},
  author = {Rachel Skipper and Stefan Witzel and Matthew C. B. Zaremsky},
  journal= {arXiv preprint arXiv:1712.05361},
  year   = {2018}
}

Comments

25 pages. v2: incorporated comments v3: final version, to appear, Invent. Math

R2 v1 2026-06-22T23:18:24.778Z