English

Irregular $\mathcal{B}$-free Toeplitz sequences via Besicovitch's construction of sets of multiples without density

Dynamical Systems 2021-01-05 v1

Abstract

Modifying Besicovitch's construction of a set B\mathcal{B} of positive integers whose set of multiples MB\mathcal{M}_{\mathcal{B}} has no asymptotic density, we provide examples of such sets B\mathcal{B} for which η:=1ZMB{0,1}Z\eta:=1_{\mathbb{Z}\setminus\mathcal{M}_{\mathcal{B}}}\in\{0,1\}^{\mathbb{Z}} is a Toeplitz sequence. Moreover our construction produces examples, for which η\eta is not only quasi-generic for the Mirsky measure (which has discrete dynamical spectrum), but also for some measure of positive entropy. On the other hand, modifying slightly an example from Kasjan, Keller, and Lema\'nczyk, we construct a set B\mathcal{B} for which η\eta is an irregular Toeplitz sequence but for which the orbit closure of η\eta in {0,1}Z\{0,1\}^{\mathbb{Z}} is uniquely ergodic.

Keywords

Cite

@article{arxiv.2101.00655,
  title  = {Irregular $\mathcal{B}$-free Toeplitz sequences via Besicovitch's construction of sets of multiples without density},
  author = {Gerhard Keller},
  journal= {arXiv preprint arXiv:2101.00655},
  year   = {2021}
}