A Recurrence-type Strong Borel--Cantelli Lemma for Axiom A Diffeomorphisms
Alejandro Rodriguez Sponheimer
TL;DR
The paper addresses strong recurrence laws for shrinking targets in dynamical systems with dependence, focusing on Axiom A diffeomorphisms. It develops a framework based on exponential decay of $3$-fold correlations for Lipschitz observables to bound recurrence sets $E_n=\{x: T^{n}x \u203a B(x,r_n(x)) ext{ for } bmu ext{-a.e. }x ext{} ight ight ext{, and applies Persson’s strong Borel–Cantelli criterion to obtain } \lim_{n\toty}rac{ sum_{k=1}^{n} oldsymbol{1}_{B_k(x)}(T^{k}x)}{ sum_{k=1}^{n} bmu(B_k(x))} = 1$. The main result holds under natural geometric assumptions on balls, annuli, and packings, with $(M_n) o0$ at a controlled rate; this yields a general recurrence theorem (Theorem general) and, for Axiom A diffeomorphisms with Hölder potentials, the specific corollaries (Theorems main) applying to equilibrium states. The work also derives a hitting-time consequence $ lim_{r o0} rac{ log au_{B(x,r)}(x)}{- log bmu(B(x,r))}=1$ and connects these recurrence rates to pointwise dimensions, providing a significant extension of recurrence results from one-dimensional or specially structured systems to broad hyperbolic settings with meaningful geometric measures.
Abstract
Let $(X,μ,T,d)$ be a metric measure-preserving dynamical system such that $3$-fold correlations decay exponentially for Lipschitz continuous observables. Given a sequence $(M_k)$ that converges to $0$ slowly enough, we obtain a strong dynamical Borel--Cantelli result for recurrence, i.e., for $μ$-a.e. $x\in X$ \[ \lim_{n \to \infty}\frac{\sum_{k=1}^{n} \mathbf{1}_{B_k(x)}(T^{k}x)} {\sum_{k=1}^{n} μ(B_k(x))} = 1, \] where $μ(B_k(x)) = M_k$. In particular, we show that this result holds for Axiom A diffeomorphisms and equilibrium states under certain assumptions.
