English

A note on multivariate diam mean equicontinuity and frequent stability

Dynamical Systems 2025-07-01 v1

Abstract

Let (X,G)(X,G) be a topological dynamical system, given by the action of a is a countable discrete infinite group on a compact metric space XX. We prove that if (X,G)(X,G) is minimal, then it is either diam-mean mm-equicontinuious or diam-mean mm-sensitive. Similarly, (X,G)(X,G) is either frequently mm-stable or strongly mm-spreading. Further, when GG is abelian (or, more generally, virtually nilpotent), then the following statements are equivalent: \bullet (X,G)(X,G) is a regular mm-to-one extension of its maximal equicontinuous factor; \bullet (X,G)(X,G) is diam-mean (m+1)(m+1)-equicontinuious, and not diam mean mm-equicontinuious; \bullet (X,G)(X,G) is not diam-mean (m+1)(m+1)-sensitive, but diam mean mm-sensitive; \bullet (X,G)(X,G) has an essential weakly mean sensitive mm-tuple but no essential weakly mean sensitive (m+1)(m+1)-tuple. This provides a {\em \enquote*{local}} characterisation of mm-regularity and mean mm-sensitivity vial weakly mean sensitive tuples. The same result holds when GG is amenable and (X,G)(X,G) satisfies the local Bronstein condition.

Cite

@article{arxiv.2506.23313,
  title  = {A note on multivariate diam mean equicontinuity and frequent stability},
  author = {Lino Haupt and Tobias Jäger and Chunlin Liu},
  journal= {arXiv preprint arXiv:2506.23313},
  year   = {2025}
}
R2 v1 2026-07-01T03:38:36.993Z