English

A note on semi-conjugacy for circle actions

Geometric Topology 2016-06-08 v3 Differential Geometry Group Theory

Abstract

We define a notion of semi-conjugacy between orientation-preserving actions of a group on the circle, which for fixed point free actions coincides with a classical definition of Ghys. We then show that two circle actions are semi-conjugate if and only if they have the same bounded Euler class. This settles some existing confusion present in the literature.

Keywords

Cite

@article{arxiv.1410.8350,
  title  = {A note on semi-conjugacy for circle actions},
  author = {Michelle Bucher and Roberto Frigerio and Tobias Hartnick},
  journal= {arXiv preprint arXiv:1410.8350},
  year   = {2016}
}

Comments

39 pages. Improved version of the previous manuscript, incorporating further historical remarks and a discussion of the equivalence between semiconjugacy and monotone equivalence

R2 v1 2026-06-22T06:41:48.025Z