On the variational principle for a class of skew product transformations

TL;DR

This paper establishes a variational principle linking fiber Bowen's topological entropy and fiber measure-theoretic entropy for certain skew product systems with unique ergodicity and mixing properties, using fiber specification.

Contribution

It proves a variational principle for a class of skew product transformations with unique ergodicity, including systems with Anosov and topological mixing properties on fibers.

Findings

Established a variational principle for fiber entropy and topological entropy.

Proved the skew product has the specification property.

Demonstrated unique equilibrium states for H"older continuous potentials.

Abstract

In this paper, we establish a variational principle, between the fiber Bowen's topological entropy on conditional level sets of Birkhoff average and fiber measure-theoretical entropy, for the skew product transformation driven by a uniquely ergodic homeomorphism system satisfying Anosov and topological mixing on fibers property. We prove it by utilizing a fiber specification property. Moreover, we prove that such skew product transformation has specification property defined by Gundlach and Kifer. Employing their main results, every H\"older continuous potential has a unique equilibrium state, and we also establish a variational principle between the fiber measure-theoretic entropy and the fiber Bowen's topological entropy on conditional level sets of local entropy for such unique equilibrium state. Examples of systems under consideration are given, such as fiber Anosov maps on 2-dimension tori driven by any irrational rotation on circle and random composition of 2x2 area preserving positive matrices driven by uniquely ergodic subshift.