English

Mapping class groups of covers with boundary and braid group embeddings

Geometric Topology 2020-03-11 v2 Group Theory

Abstract

We consider finite-sheeted, regular, possibly branched covering spaces of compact surfaces with boundary and the associated liftable and symmetric mapping class groups. In particular, we classify when either of these subgroups coincides with the entire mapping class group of the surface. As a consequence, we construct infinite families of non-geometric embeddings of the braid group into mapping class groups in the sense of Wajnryb. Indeed, our embeddings map standard braid generators to products of Dehn twists about curves forming chains of arbitrary length. As key tools, we use the Birman-Hilden theorem and the action of the mapping class group on a particular fundamental groupoid of the surface.

Keywords

Cite

@article{arxiv.1804.10609,
  title  = {Mapping class groups of covers with boundary and braid group embeddings},
  author = {Tyrone Ghaswala and Alan McLeay},
  journal= {arXiv preprint arXiv:1804.10609},
  year   = {2020}
}

Comments

34 pages, 13 figures. Changes suggested by the referee have been made, minor typos fixed. To appear in Algebraic & Geometric Topology

R2 v1 2026-06-23T01:38:26.647Z