Almost sure convergence of cover times for $\psi$-mixing systems

TL;DR

This paper studies the asymptotic behavior of cover times in certain dynamical systems, introducing a new dimension concept and demonstrating its effectiveness in systems with complex structures.

Contribution

It introduces the stretched Minkowski dimension and shows its relevance in determining cover time asymptotics in mixing systems, extending previous Minkowski dimension results.

Findings

Stretched Minkowski dimension determines cover time asymptotics.

Standard Minkowski dimension fails for certain affine maps.

Explicit cover time calculations for irrational rotations.

Abstract

Given a topologically transitive system on the unit interval, one can investigate the cover time, i.e. time for an orbit to reach certain level of resolution in the repeller. We introduce a new notion of dimension, namely the stretched Minkowski dimension, and show that under mixing conditions, the asymptotics of typical cover times are determined by Minkowski dimensions when they are finite, or by stretched Minkowski dimensions otherwise. For application, we show that for countably full-branched affine maps, results using the usual Minkowski dimensions fail to produce a finite log limit of cover times whilst the stretched version gives an finite limit. In addition, cover times of irrational rotations are explicitly calculated as counterexamples, due to the absence of mixing.