On substitution tilings and Delone sets without finite local complexity

TL;DR

This paper investigates substitution tilings and Delone sets lacking finite local complexity, providing conditions for unique ergodicity, analyzing their ergodic properties, and extending known equivalences under a rigidity assumption.

Contribution

It introduces a sufficient condition for unique ergodicity in non-FLC tilings and extends key spectral equivalences to this broader setting with a rigidity assumption.

Findings

Tilings without FLC can be uniquely ergodic under certain conditions.

Absence of strong mixing in these systems.

Eigenvalue properties relate to number-theoretic conditions like Pisot families.

Abstract

We consider substitution tilings and Delone sets without the assumption of finite local complexity (FLC). We first give a sufficient condition for tiling dynamical systems to be uniquely ergodic and a formula for the measure of cylinder sets. We then obtain several results on their ergodic-theoretic properties, notably absence of strong mixing and conditions for existence of eigenvalues, which have number-theoretic consequences. In particular, if the set of eigenvalues of the expansion matrix is totally non-Pisot, then the tiling dynamical system is weakly mixing. Further, we define the notion of rigidity for substitution tilings and demonstrate that the result of [Lee-Solomyak (2012)] on the equivalence of four properties: relatively dense discrete spectrum, being not weakly mixing, the Pisot family, and the Meyer set property, extends to the non-FLC case, if we assume rigidity instead.