Surface groups are flexibly stable

Research output: Contribution to journalArticlepeer-review

Abstract

We show that surface groups are flexibly stable in permutations. This is the first nontrivial example of a non-amenable flexibly stable group. Our method is purely geometric and relies on an analysis of branched covers of hyperbolic surfaces. Along the way we establish a quantitative variant of the LERF property for surface groups which may be of independent interest.

Original languageEnglish
Pages (from-to)1739-1768
Number of pages30
JournalJournal of the European Mathematical Society
Volume27
Issue number4
DOIs
StatePublished - 2025

Keywords

  • CAT.‒1/
  • LERF
  • Stability in permutations
  • combinatorial group theory
  • flexible stability
  • surface groups

All Science Journal Classification (ASJC) codes

  • General Mathematics
  • Applied Mathematics

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