Anisotropic Minkowski Content for Countably $\mathcal{H}^k$-rectifiable Sets
Filip Fryš
TL;DR
This work extends Federer’s isotropic, lower-dimensional Minkowski content to anisotropic settings, showing that for a $k$-rectifiable compact set $S$ and any convex body $C$, the $C$-anisotropic $k$-Minkowski content exists and equals $\mathcal{M}^k_{C}(S)=\frac{1}{\omega_{n-k}}\int_S \mathcal{H}^{n-k}(C_x)\,d\mathcal{H}^k(x)$ with $C_x = P_{(\textup{T}^k_x S)^{\perp}}(C)$. Under a suitable AFP-condition (and its relative-$L$ version), this result extends to countably $\mathcal{H}^k$-rectifiable compact sets, with the same integral representation, while the case balance $k+m-n$ dictates whether a positive lower bound, an exact integral form, or a zero limit holds. The paper also proves that, once the content exists for one full-dimensional $C$, it exists and yields the same value for all full-dimensional convex bodies. These results generalize classical isotropic findings to anisotropic, lower-dimensional contexts, enriching the geometric measure theory toolkit for analyzing anisotropic volumes and their dependence on the structuring body $C$.
Abstract
This paper investigates the existence of the anisotropic lower-dimensional Minkowski content. We establish that the $C$-anisotropic $k$-dimensional Minkowski content of a $k$-rectifiable compact set always exists and coincides with a specific functional that depends naturally on $C$. We further show that the same conclusion holds for countably $\mathcal{H}^k$-rectifiable compact sets, provided that the so-called \emph{AFP-condition} is satisfied. In addition, we discuss how the existence of the $C$-anisotropic $k$-dimensional Minkowski content for a countably $\mathcal{H}^k$-rectifiable compact set depends on the choice of $C$.
