English

Baumslag-Solitar relations in abstract commensurators of free groups

Group Theory 2020-03-18 v2

Abstract

Any non-residually finite Baumslag-Solitar group has a non-residually finite image in the abstract commensuration of a nonabelian free group. This gives a new proof (avoiding Britton's Lemma) of the classification of residually finite Baumslag-Solitar groups.

Keywords

Cite

@article{arxiv.2003.06644,
  title  = {Baumslag-Solitar relations in abstract commensurators of free groups},
  author = {Khalid Bou-Rabee and Samuel Young},
  journal= {arXiv preprint arXiv:2003.06644},
  year   = {2020}
}

Comments

9 pages, corrected the main theorem and corollary statements. We mistakenly thought we were addressing whether the BS groups are Hopfian