Higher-Dimensional Moving Averages and Submanifold Genericity

Abstract: We generalize results of Bellow, Jones, and Rosenblatt on moving ergodic averages to measure-preserving actions of $\mathbb Z^d$ and $\mathbb R^d$ for $d\geq 1$. In particular, we give necessary and sufficient conditions for the pointwise convergence of certain sequences of functions defined by averaging over families of boxes in $\mathbb Z^d$ and $\mathbb R^d$. As an application of our characterization, we show that averages along dilates of "locally flat" submanifolds in $\mathbb R^d$ do not necessarily converge point-wise for bounded measurable functions. This is closely related to the concept of submanifold-genericity recently introduced in [BFK25].