Spatial-Temporal Differentiation Theorems

Let $(X, \mathcal{B}, μ, T)$ be a dynamical system where $X$ is a compact metric space with Borel $σ$-algebra $\mathcal{B}$, and $μ$ is a probability measure that's ergodic with respect to the homeomorphism $T : X \to X$. We study the following differentiation problem: Given $f \in C(X)$ and $F_k \in \mathcal{B}$, where $μ(F_k) > 0$ and $μ(F_k) \to 0$, when can we say that $\lim_{k \to \infty} \frac{\int_{F_k} \left( \frac{1}{k} \sum_{i = 0}^{k - 1} T^i f \right) \mathrm{d} μ}{μ(F_k)} = \int f \mathrm{d} μ?$

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