English

Components of spaces of surface group representations

Geometric Topology 2013-11-14 v2 Dynamical Systems

Abstract

We give a new lower bound on the number of connected components of the space of representations of a surface group into the group of orientation preserving homeomorphisms of the circle. Precisely, for the fundamental group of a genus g surface, we show there are at least k^(2g) + 1 connected components containing representations with Euler number (2g-2)/(k). We also show that certain representations are rigid, meaning that all deformations lie in the same semiconjugacy class. Our methods apply to representations of surface groups into finite covers of PSL(2,R) and into Diff+(S^1) as well, in which case we recover theorems of W. Goldman and J. Bowden. The key technique is an investigation of local maximality phenomena for rotation numbers of products of circle homeomorphisms, using techniques of Calegari-Walker. This is a new approach to studying deformation classes of group actions on the circle, and may be of independent interest.

Keywords

Cite

@article{arxiv.1309.2905,
  title  = {Components of spaces of surface group representations},
  author = {Kathryn Mann},
  journal= {arXiv preprint arXiv:1309.2905},
  year   = {2013}
}

Comments

Version 2 improves on the original by reproving the main theorems for topological rather than path components (using new arguments in some cases). We also remark on sharpness of our results