Hausdorff content $A_p$ weights: weighted maximal inequalities and fundamental structural properties

Abstract

Let ${\mathcal{H}}_{\infty }^{\delta }$ denote the Hausdorff content of dimension $\delta \in (0,n]$ defined on subsets of ${\mathbb{R}}^n$. The principal problem, considered in this paper, is to characterize the non-negative function $w$ for which the weighted $L^p$ inequality with $p\in (1,\infty )$ and the weighted weak $L^1$ inequality on Hardy-Littlewood maximal operators associated with Hausdorff content hold true. To achieve this, we introduce a class of Hausdorff content $A_p$ weights, denoted as ${\mathcal{A}}_{p,\delta }$, and then show that, for any $p\in (1,\infty )$ and $\delta \in (0,n]$, the weighted $L^p$ maximal inequality holds true if and only if $w\in {\mathcal{A}}_{p,\delta }$, and the weighted weak $L^1$ maximal inequality holds true if and only if $w\in {\mathcal{A}}_{1,\delta }$ by proposing a novel approach. As the second objective, applying this approach, the seminal structural properties of classical Muckenhoupt $A_p$ weights, such as the reverse Hölder inequality [R. R. Coifman and C. Fefferman, Studia Math. 51 (1974), 241-250], the self-improving property [B. Muckenhoupt, Trans. Amer. Math. Soc. 165 (1972), 207-226], and Jones' factorization theorem [P. W. Jones, Ann. of Math. (2) 111 (1980), 511-530], are all established for ${\mathcal{A}}_{p,\delta }$. The main novelties of this paper lies in: (i) we discover ${\mathcal{A}}_{p,\delta }$ weights with rich structural properties, that increase strictly on dimension exponent and hence reduce to the classical $A_p$ class at the endpoint dimension, forming proper subsets of it for smaller dimension exponent; (ii) by proposing a novel approach, this work naturally extends the classical theory beyond measure-theoretic frameworks, while also provides novel insights even when reduced to the classical $A_p$ weight case.

arXiv comment52 pages