English

Planar boundaries and parabolic subgroups

Group Theory 2022-04-18 v3 Geometric Topology

Abstract

We study the Bowditch boundaries of relatively hyperbolic group pairs, focusing on the case where there are no cut points. We show that if (G,P)(G,\mathcal{P}) is a rigid relatively hyperbolic group pair whose boundary embeds in S2S^2, then the action on the boundary extends to a convergence group action on S2S^2. More generally, if the boundary is connected and planar with no cut points, we show that every element of P\mathcal{P} is virtually a surface group. This conclusion is consistent with the conjecture that such a group GG is virtually Kleinian. We give numerous examples to show the necessity of our assumptions.

Keywords

Cite

@article{arxiv.2008.07639,
  title  = {Planar boundaries and parabolic subgroups},
  author = {G. Christopher Hruska and Genevieve S. Walsh},
  journal= {arXiv preprint arXiv:2008.07639},
  year   = {2022}
}

Comments

25 pages; minor edits and clarifications in this version

R2 v1 2026-06-23T17:55:22.879Z