English

Extensions of hyperbolic groups have locally uniform exponential growth

Group Theory 2021-01-01 v1 Geometric Topology

Abstract

We introduce a quantitative characterization of subgroup alternatives modeled on the Tits alternative in terms of group laws and investigate when this property is preserved under extensions. We develop a framework that lets us expand the classes of groups known to have locally uniform exponential growth to include extensions of either word hyperbolic or right-angled Artin groups by groups with locally uniform exponential growth. From this, we deduce that the automorphism group of a torsion-free one-ended hyperbolic group has locally uniform exponential growth. Our methods also demonstrate that automorphism groups of torsion-free one-ended toral relatively hyperbolic groups and certain right-angled Artin groups satisfy our quantitative subgroup alternative.

Keywords

Cite

@article{arxiv.2012.14880,
  title  = {Extensions of hyperbolic groups have locally uniform exponential growth},
  author = {Robert Kropholler and Rylee Alanza Lyman and Thomas Ng},
  journal= {arXiv preprint arXiv:2012.14880},
  year   = {2021}
}

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R2 v1 2026-06-23T21:34:07.417Z