A Class of De Giorgi Type and Hölder Continuity for Some Problems in Musielak-Orlicz-Sobolev Spaces
Hlel Missaoui, Anouar Bahrouni, Hichem Ounaies
TL;DR
This work develops a nonstandard regularity theory for quasilinear elliptic equations with Musielak–Orlicz growth. By introducing the De Giorgi-type class $\mathcal{B}_{G(x,t)}$, it obtains Hölder continuity under general structural assumptions on $G(x,t)$, including critical growth scenarios, and accommodates both Dirichlet and Neumann boundary conditions. The authors establish boundedness of weak solutions and local (plus up-to-boundary) Hölder regularity via a novel De Giorgi iteration adapted to Musielak–Orlicz–Sobolev spaces, unifying and extending variable-exponent and Orlicz-type results. The results have broad applicability to a wide spectrum of nonhomogeneous growth models, including $(p(x),q(x))$-growth and double-phase-like frameworks, and provide a robust toolkit for regularity in nonstandard growth PDEs.
Abstract
In this paper, we introduce a new class of De Giorgi type functions, denoted by \(\mathcal{B}_{G(x,t)}\), and establish the Hölder continuity of its elements under suitable additional assumptions on the generalized \textnormal{N}-function \(G(x,t)\). As an application, we prove the Hölder continuity of solutions to quasilinear equations whose principal part is in divergence form with \(G(x,t)\)-growth conditions, including both critical and standard growth cases. The novelty of our work lies in the generalization of the Hölder continuity results previously known for variable exponent \cite[X, Fan and D. Zhao]{Fan1999} and Orlicz \cite[G. M. Lieberman]{Li1991} problems. Moreover, our results encompass a wide variety of quasilinear equations.
