English

A set of 2-recurrence whose perfect squares do not form a set of measurable recurrence

Dynamical Systems 2024-05-08 v2 Combinatorics

Abstract

We say that SZS\subset\mathbb Z is a set of kk-recurrence if for every measure preserving transformation TT of a probability measure space (X,μ)(X,\mu) and every AXA\subseteq X with μ(A)>0\mu(A)>0, there is an nSn\in S such that μ(ATnAT2nTknA)>0\mu(A\cap T^{-n} A\cap T^{-2n}\cap \dots \cap T^{-kn}A)>0. A set of 11-recurrence is called a set of measurable recurrence. Answering a question of Frantzikinakis, Lesigne, and Wierdl, we construct a set of 22-recurrence SS with the property that {n2:nS}\{n^2:n\in S\} is not a set of measurable recurrence.

Keywords

Cite

@article{arxiv.2207.11851,
  title  = {A set of 2-recurrence whose perfect squares do not form a set of measurable recurrence},
  author = {John T. Griesmer},
  journal= {arXiv preprint arXiv:2207.11851},
  year   = {2024}
}

Comments

47 Pages; v.2 incorporates referee suggestions