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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.

A Class of De Giorgi Type and Hölder Continuity for Some Problems in Musielak-Orlicz-Sobolev Spaces

TL;DR

This work develops a nonstandard regularity theory for quasilinear elliptic equations with Musielak–Orlicz growth. By introducing the De Giorgi-type class , it obtains Hölder continuity under general structural assumptions on , 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 -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.

Paper Structure

This paper contains 13 sections, 25 theorems, 267 equations.

Key Result

Theorem 1.2

Suppose that the function $G(x,t)$ satisfies conditions D22--GG1 and GG3. Then the De Giorgi-type class belongs to a Hölder space: where the Hölder exponent $\alpha \in (0,1]$ depends only on the parameters $n, g^-, g^+, F, L:=\exp{L_0}, \gamma$, and $\delta$, and is independent of $M$ and $\gamma_1$.

Theorems & Definitions (67)

  • Definition 1.1
  • Theorem 1.2
  • Definition 1.3: see Sect. 1, Chapter 1 OL
  • Definition 1.4: see Sect. 1, of Chap. I of OL
  • Theorem 1.5
  • Remark 1.6
  • Definition 1.7
  • Definition 1.8
  • Theorem 1.9
  • Theorem 1.10
  • ...and 57 more