Subcohomology and a Livsic Theorem for Zooming Systems

TL;DR

This paper extends Livsic-type theorems to a broad class of zooming systems, establishing conditions under which certain potentials admit continuous solutions and proving uniqueness of maximizing measures.

Contribution

It generalizes Livsic's theorem and cohomological results to non-uniformly expanding systems with critical sets, including Viana and Benedicks-Carleson maps.

Findings

Proves existence of continuous solutions for H"older potentials under zooming conditions.

Establishes a Livsic theorem for systems with zero integral potentials and dense periodic points.

Shows uniqueness of maximizing measures for a residual set of potentials.

Abstract

In the context of continuous zooming systems $f:M \to M$ on a compact metric space $M$, which include the non-uniformly expanding ones, possibly with the presence of a critical set, with the zooming set dense in $M$, we prove that any H\"older potential $\phi : M \to \mathbb{R}$ for which the integrals $\int \phi d\mu \geq 0$ with respect to any $f$-invariant probability $\mu$, admits a continuous function $\lambda_{0} : M \to \mathbb{R}$ (which can be H\"older if some integral is positive) such that \[ \phi \geq \lambda_{0}- \lambda_{0} \circ f. \] This extends a result in [9] for $C^{1}$-expanding maps on the circle $\mathbb{T} = \mathbb{R}/\mathbb{Z}$ to important classes of maps as uniformly expanding, local diffeomorphisms with non-uniform expansion, Viana maps, Benedicks-Carleson maps and Rovella maps. We also give an example beyond the exponential contractions context. Moreover, in the case of the integrals $\int \phi d\mu = 0$ with respect to any $f$-invariant probability $\mu$ and the set of periodic points to be dense in $M$, we obtain a version of the Livsic Theorem, that is, the functions $\lambda_{0}$ can be taken such that \[ \phi = \lambda_{0}- \lambda_{0} \circ f. \] Additionally, we also prove that the measure which maximizes the integrals is unique for a residual set of potentials.