Quasi-shadowing property for nonuniformly partially hyperbolic systems
Gang Liao, Xuetong Zu
TL;DR
The paper develops a quasi-shadowing theory for nonuniformly partially hyperbolic diffeomorphisms by constructing fake center foliations and proving Hölder continuity of invariant bundles on Pesin blocks, enabling shadowing that adapts to pseudo-orbit movement. It derives quasi-specification and quasi-closing results as corollaries, illustrating robust orbit concatenation and near-periodic behavior under center-direction motion. The main application shows that the exponential growth rate of quasi-periodic points matches the metric entropy for ergodic measures, extending Katok’s entropy-periodic point connection to a broader nonuniform setting. Together, these results provide a framework for analyzing stability, orbit approximation, and complexity in nonuniformly partially hyperbolic dynamics with potential implications for entropy and periodic-point theory.
Abstract
In this paper, we establish a new quasi-shadowing property for any nonuiformly partially hyperbolic set of a $C^{1+α}$ diffeomorphism, which is adaptive to the movement of the pseudo-orbit. Moreover, the quasi-specification property and quasi-closing property are also investigated. As an application of quasi-closing property, we extend Katok's reslut on the growth of periodoc orbits for hyperbolic ergodic measure to any ergodic measure: the number of quasi-periodic points grows exponentially at least the metric entropy.
