English

Conjugacy classes of big mapping class groups

Geometric Topology 2021-11-22 v3 Dynamical Systems Logic

Abstract

We describe the topological behavior of the conjugacy action of the mapping class group of an orientable infinite-type surface Σ\Sigma on itself. Our main results are: (1) All conjugacy classes of MCG(Σ)MCG(\Sigma) are meager for every Σ\Sigma, (2) MCG(Σ)MCG(\Sigma) has a somewhere dense conjugacy class if and only if Σ\Sigma has at most two maximal ends and no non-displaceable finite-type subsurfaces, (3) MCG(Σ)MCG(\Sigma) has a dense conjugacy class if and only if Σ\Sigma has a unique maximal end and no non-displaceable finite-type subsurfaces. Our techniques are based on model-theoretic methods developed by Kechris, Rosendal and Truss.

Keywords

Cite

@article{arxiv.2105.11282,
  title  = {Conjugacy classes of big mapping class groups},
  author = {Jesús Hernández Hernández and Michael Hrušák and Israel Morales and Anja Randecker and Manuel Sedano and Ferrán Valdez},
  journal= {arXiv preprint arXiv:2105.11282},
  year   = {2021}
}

Comments

v3. Corrected version after revision. To appear in J. London Math. Soc

R2 v1 2026-06-24T02:24:25.897Z