English

Configuration space, moduli space and 3-fold covering space

Algebraic Topology 2018-02-05 v1

Abstract

A function from configuration space to moduli space of surface may induce a homomorphism between their fundamental groups which are braid groups and mapping class groups of surface, respectively. This map ϕ:BkΓg,b\phi: B_k \rightarrow \Gamma_{g,b} is induced by 3-fold branched covering over a disk with some branch points. In this thesis we give a concrete description of this map and show that it is injective by Birman-Hilden theory. This gives us a new interesting non-geometric embedding of braid group into mapping class group. On the other hand, we show that the map on the level of classifying spaces of groups is compatible with the action of little 2-cube operad so that it induces a trivial homomorphim between stable homology group of braid groups and that of mapping class groups(Harer conjecture). We also show how the lift βi~\tilde{\beta_i} acts on the fundamental group of the surface and through this we prove that βi~\tilde{\beta_i} equals the product of two inverse Dehn twists.

Keywords

Cite

@article{arxiv.1802.00594,
  title  = {Configuration space, moduli space and 3-fold covering space},
  author = {Byung Chun Kim and Yongjin Song},
  journal= {arXiv preprint arXiv:1802.00594},
  year   = {2018}
}

Comments

17 pages, 19 figures

R2 v1 2026-06-23T00:08:28.037Z