Interior Regularity of Mixed Local-Nonlocal Parabolic Semilinear Equations

Abstract: In this paper we prove the existence, uniqueness and regularity of classical solutions \break of a semilinear parabolic equation with a mixed local and nonlocal diffusion operator \break $\mathcal{L} = -(-Δ)^s + Δ$ and Dirichlet boundary conditions. Here, $(-Δ)<sup>s$ is the integral fractional laplacian and $Δ$ is the classic local laplacian. We then study the interior regularity of said solutions and conclude that they are Hölder continuous in both space and time, and they are $C<sup>{2,α}_{loc}$ in space for all positive times.