Let $ ([0,1]^d,T,\mu) $ be a measure-preserving dynamical system so that the correlations decay exponentially for H\"older continuous functions. Suppose that $ \mu $ is absolutely continuous with a density function $ h\in L^q(\mathcal L^d) $ for some $ q>1 $, where $ \mathcal L^d $ is the $ d $-dimensional Lebesgue measure. Under mild conditions on the underlying dynamical system, we obtain a strong dynamical Borel-Cantelli lemma for recurrence: For any sequence $ \{ R_n\} $ of hyperrectangles with sides parallel to the axes and centered at the origin, \[\sum_{ n=1}^{ \infty}\mathcal L^d(R_n)=\infty\quad\Longrightarrow\quad\lim_{ n\to\infty}\frac{ \sum_{ k=1}^{ n}\chi_{ R_k+\mathbf{ x}}(T^k\mathbf{ x})}{ \sum_{ k=1}^{ n}\mathcal L^d(R_k)}=h(\mathbf{ x})\quad\text{ for $ \mu $-a.e.$\textbf{ x}$},\] where $ \textbf{ x}\in[0,1]^d $ and $ R_k+\textbf{ x} $ is the translation of $ R_k $. The result applies to Gauss map, $\beta$-transformation and expanding toral endomorphisms.
Categories: math.DS