English

Continuity of measurable cocycles

Group Theory 2026-01-14 v2 Logic

Abstract

Suppose GXG\curvearrowright X is a Polish group action, HH is a Polish group and G×XψHG\times X\overset{\psi}\longrightarrow H is a cocycle that is continuous in the second variable. If ψ\psi is either Baire measurable or is λ×μ\lambda\times \mu-measurable with respect to a Haar measure λ\lambda on GG and a fully supported σ\sigma-finite Borel measure μ\mu on XX, then ψ\psi is jointly continuous.

Keywords

Cite

@article{arxiv.2502.01581,
  title  = {Continuity of measurable cocycles},
  author = {Christian Rosendal},
  journal= {arXiv preprint arXiv:2502.01581},
  year   = {2026}
}

Comments

This version differs from the previous one entitled "Almost homomorphisms and measurable cocycles" in several regards. First of all, the part on almost homomorphisms has been eliminated due to an overlap with the literature. Secondly, the results on measurable cocycles have been strengthened

R2 v1 2026-06-28T21:30:57.075Z