English

Continuous Cocycle Superrigidity for Shifts and Groups with One End

Dynamical Systems 2017-10-10 v2 Group Theory

Abstract

In this article, we prove that if a finitely generated group GG is not torsion then a necessary and sufficient condition for every full shift over GG has (continuous) cocycle superrigidity is that GG has one end. It is a topological version of the well known Popa's measurable cocycle superrigidity theorem. For the proof of sufficient condition, we introduce a new specification property for shifts over general groups which play a similar role as malleable property in the measurable setting. This new specification property is good enough for us to extend the method using homoclinic equivalence relation that was introduced by Klaus Schmidt to study cocycle rigidity for Zd\mathbb{Z}^d-shifts. Indeed, in this direction we prove this superrigidity result for more certain general systems. And for the converse, we apply Specker's characterization for ends of groups via the associated first cohomology groups to get the result. Finally, combining our results with a result of Xin Li, we have an application in continuous orbit equivalence rigidity.

Keywords

Cite

@article{arxiv.1603.00114,
  title  = {Continuous Cocycle Superrigidity for Shifts and Groups with One End},
  author = {Nhan-Phu Chung and Yongle Jiang},
  journal= {arXiv preprint arXiv:1603.00114},
  year   = {2017}
}

Comments

Introduction is expanded and several references are added

R2 v1 2026-06-22T13:00:34.123Z