Strong $(L^2,L^\gamma\cap H_0^1)$-continuity in initial data of nonlinear reaction-diffusion equation in any space dimension

TL;DR

This paper proves strong continuity of solutions to nonlinear reaction-diffusion equations in initial data across various function spaces, regardless of space dimension, and explores implications for global attractors and their finite dimensionality.

Contribution

It establishes $(L^2, L^3\cap H_0^1)$-continuity of solutions for reaction-diffusion equations in any space dimension, removing previous restrictions and applying to global attractors.

Findings

Solutions are continuous in initial data in $L^3$-norms.

Global attractors attract bounded sets in stronger norms.

Finite dimensionality of translation sets of attractors.

Abstract

In this paper, we study the continuity in initial data of a classical reaction-diffusion equation with arbitrary $p>2$ order nonlinearity and in any space dimension $N\geq 1$. It is proved that the weak solutions can be $(L^2, L^\gamma\cap H_0^1)$-continuous in initial data for any $\gamma\geq 2$ (independent of the physical parameters of the system), i.e., can converge in the norm of any $L^\gamma\cap H_0^1$ as the corresponding initial values converge in $L^2$. Applying this to the global attractor we find that, with external forcing only in $ L^2$, the attractor $\mathscr{A}$ attracts bounded subsets of $L^2$ in the norm of any $L^\gamma\cap H_0^1$, and that every translation set $\mathscr{A}-z_0$ of $\mathscr{A}$ for any $z_0 \in \mathscr{A}$ is a finite dimensional compact subset of $L^\gamma\cap H_0^1$. The main technique we employ is a combination of the mathematical induction and a decomposition of the nonlinearity by which the continuity result is strengthened to $(L^2, L^\gamma \cap H_0^1)$-continuity and, since interpolation inequalities are avoided, the restriction on space dimension is removed.