Pesin's Entropy Formula for $C^1$ non-uniformly expanding maps

TL;DR

This paper extends Pesin's Entropy Formula to $C^1$ non-uniformly expanding maps, establishing the existence of equilibrium states and characterizing measures satisfying the formula.

Contribution

It provides a $C^1$ generalization of Pesin's Entropy Formula and links weak-SRB-like measures with equilibrium states for non-uniformly expanding maps.

Findings

Existence of equilibrium states with special properties.

Weak-SRB-like measures satisfy Pesin's Entropy Formula.

For $C^1$-expanding maps, measures satisfying the formula form a convex hull.

Abstract

We prove existence of equilibrium states with special properties for a class of distance expanding local homeomorphisms on compact metric spaces and continuous potentials. Moreover, we formulate a C$^1$ generalization of Pesin's Entropy Formula: all ergodic weak-SRB-like measures satisfy Pesin's Entropy Formula for $C^1$ non-uniformly expanding maps. We show that for weak-expanding maps such that $\Leb$-a.e $x$ has positive frequency of hyperbolic times, then all the necessarily existing ergodic weak-SRB-like measures satisfy Pesin's Entropy Formula and are equilibrium states for the potential $\psi=-\log|\det Df|$. In particular, this holds for any $C^1$-expanding map and in this case the set of invariant probability measures that satisfy Pesin's Entropy Formula is the weak$^*$-closed convex hull of the ergodic weak-SRB-like measures.