Hölder regularity for degenerate parabolic double-phase equations
Wontae Kim, Kristian Moring, Lauri Särkiö
TL;DR
This work establishes local Hölder continuity for bounded weak solutions to parabolic double-phase equations with nonstandard growth $\partial_t u - \operatorname{div}\mathcal{A}(x,t,u,\nabla u)=0$, where $2\le p<q\le p+\alpha$ and $a\in C^{\alpha,\alpha/2}$ satisfies $q\le p+\alpha$. The authors introduce an intrinsic, phase-based framework that identifies whether the local behavior aligns with a $p$-Laplace or a $q$-Laplace regime, and then apply De Giorgi-type energy estimates (Caccioppoli and logarithmic) in phase-appropriate cylinders. A measure-theoretic alternative, combined with a phase criterion and embedding theorems, yields two complementary routes to reduce oscillation; a recursive scheme then provides geometric decay of oscillation and a Hölder modulus with exponent $\beta$ depending on the data, including $n,p,q,\alpha,[a]_{\alpha}$, and $\|u\|_{\infty}$. The results extend parabolic regularity theory to doubly nonlinear, nonstandard-growth diffusion and offer a robust framework for further exploration of Harnack-type inequalities and gradient regularity in the double-phase setting.
Abstract
We prove that bounded weak solutions to degenerate parabolic double-phase equations of $p$-Laplace type are locally Hölder continuous. The proof is based on phase analysis and methods for the $p$-Laplace equation. In particular, the phase analysis determines whether the double-phase equation is locally similar to the $p$-Laplace or the $q$-Laplace equation.
