English

Hyperbolic Immersions of Free Groups

Group Theory 2021-10-01 v2

Abstract

We prove that the mapping torus of a graph immersion has a word-hyperbolic fundamental group if and only if the corresponding endomorphism does not produce Baumslag-Solitar subgroups. Due to a result by Reynolds, this theorem applies to all injective endomorphisms of F2F_2 and nonsurjective fully irreducible endomorphisms of FnF_n. We also give a framework for extending the theorem to all injective endomorphisms of FnF_n.

Keywords

Cite

@article{arxiv.1809.04761,
  title  = {Hyperbolic Immersions of Free Groups},
  author = {Jean Pierre Mutanguha},
  journal= {arXiv preprint arXiv:1809.04761},
  year   = {2021}
}

Comments

Argument streamlined and generalized; terminology changed; 19 pages, 4 figures

R2 v1 2026-06-23T04:04:49.128Z