Symbolic dynamics for certain non-invertible $C^{1+β}$ maps
Jing Xun, Yifan Zhang, Yujun Zhu
TL;DR
This work extends symbolic dynamics to non-invertible $C^{1+\beta}$ maps with zero Lyapunov exponents and singularities by combining ideas from Sarig, Ovadia, and Lima–Poletti. It constructs a countable Markov partition for the 0-summ subset of the natural extension and proves the existence of a finite-to-one symbolic extension that semi-conjugates the natural extension to a topological Markov shift, while lifting the geometric potential with summable variations. The approach hinges on refined Pesin theory in the presence of singularities, a ladder-function temperability framework, and a graph-transform analysis of admissible manifolds to control distortions and overlaps. The results yield entropy and periodic-point counts on the 0-summ set and provide a concrete example illustrating the applicability to singular non-invertible dynamics on compact manifolds.
Abstract
Let $f$ be a non-invertible $C^{1+β}(β>0)$ map with zero Lyapunov exponents and singularities on a closed Riemannian manifold $M$. We consider the symbolic dynamics of $f$. Combining the techniques in recent works of Sarig, Ovadia and Araujo-Lima-Poletti, we construct a countable Markov partition for the invariant set consisting of summable points of the inverse limit space of $(M, f)$ and show that there exists a finite-to-one symbolic extension for $f$ on the corresponding subset of $M$.
