English

Generalized heredity in $\mathcal B$-free systems

Dynamical Systems 2019-11-18 v3

Abstract

Let BN\mathcal B\subseteq\mathbb N be a primitive set. We complement results on heredity of the B\mathcal B-free subshift XηX_\eta from [arxiv:1509.08010] in two directions: In the proximal case we prove that a subshift XφX_\varphi, which micht be slightly larger than the subshift XηX_\eta, is always hereditary. (There is no need to assume that the set B\mathcal B is taut or even has light tails, but if B\mathcal B is taut, then Xφ=XηX_\varphi=X_\eta.) We also generalize the the concept of heredity to the non-proximal (and hence non-hereditary) case by proving that XφX_\varphi is always "hereditary away from its unique minimal subsystem" (which is always Toeplitz). Finally we characterize regularity of this Toeplitz subsystem equivalently by the condition mH(int(W))=0m_H(\overline{\operatorname{int}(W)})=0, where WW ("the window") is a subset of a compact abelian group HH canonically associated with the set B\mathcal B, and mHm_H denotes Haar measure on HH. Throughout, results from [arxiv:1702.02375] are heavily used.

Cite

@article{arxiv.1704.04079,
  title  = {Generalized heredity in $\mathcal B$-free systems},
  author = {Gerhard Keller},
  journal= {arXiv preprint arXiv:1704.04079},
  year   = {2019}
}

Comments

The statement and the proof of Lemma 4 (current version) were corrected. In view of [arxiv:1802.08309], stronger corrolaries to the main result could be formulated

R2 v1 2026-06-22T19:16:35.090Z