English

A counterexample to the easy direction of the geometric Gersten conjecture

Group Theory 2019-02-13 v2

Abstract

For finitely generated groups H and G, equipped with word metrics, a translation-like action of H on G is a free action such that each element of H acts by a map which has finite distance from the identity map in the uniform metric. For example, if H is a subgroup of G, then right translation by elements of H yields a translation-like action of H on G. Whyte asked whether a group with no translation-like action by a Baumslag-Solitar group must be hyperbolic, where the free abelian group of rank 2 is understood to be a Baumslag-Solitar group. We show that the converse of this conjecture is false, and in particular the fundamental group of a closed hyperbolic 3-manifold admits a translation-like action by the free abelian group of rank 2.

Keywords

Cite

@article{arxiv.1612.03491,
  title  = {A counterexample to the easy direction of the geometric Gersten conjecture},
  author = {David Bruce Cohen},
  journal= {arXiv preprint arXiv:1612.03491},
  year   = {2019}
}

Comments

5 pages, updated to clarify Whyte's question and mention relevant recent work of Jiang on the other direction of the geometric Gersten conjecture