Oscillations and differences in Besov-Morrey and Besov-type spaces
Marc Hovemann, Markus Weimar
TL;DR
This work develops intrinsic oscillation and higher-order difference characterizations for Besov-Morrey spaces $\mathcal{N}^{s}_{u,p,q}(\Omega)$ and Besov-type spaces $B^{s,\tau}_{p,q}(\Omega)$ on Lipschitz domains and $\mathbb{R}^d$. By integrating the Hedberg–Netrusov framework with Triebel’s kernel representations, the authors derive new equivalent quasi-norms based on local oscillations and higher-order differences, including domain-specific variants and special Lipschitz/convex domains. The results unify and extend classical Besov characterizations, provide tools for PDE regularity analysis, and connect function-space theory with concrete approximation measures. The methods—local oscillations, higher-order differences, Littlewood–Paley decompositions, and domain localization—offer a robust framework for analyzing regularity in Morrey-scale Besov spaces with sharp parameter ranges and domain restrictions.
Abstract
In this paper we investigate Besov-Morrey spaces $\mathcal{N}^{s}_{u,p,q}(Ω)$ and Besov-type spaces $B^{s,τ}_{p,q}(Ω)$ of positive smoothness defined on Lipschitz domains $Ω\subset \mathbb{R}^d$ as well as on $\mathbb{R}^d$. We combine the Hedberg-Netrusov approach to function spaces with distinguished kernel representations due to Triebel, in order to derive novel characterizations of these scales in terms of local oscillations provided that some standard conditions concerning the parameters are fulfilled. In connection with that we also obtain new characterizations of $\mathcal{N}^{s}_{u,p,q}(Ω)$ and $B^{s,τ}_{p,q}(Ω)$ via differences of higher order. By the way we recover and extend corresponding results for the scale of classical Besov spaces $B^{s}_{p,q}(Ω)$. Key words: Besov-Morrey space, Besov-type space, Morrey space, Lipschitz domain, oscillations, higher order differences
