Generalized Nonlocal Robin Laplacian on Arbitrary Domains

TL;DR

This paper establishes a framework for defining nonlocal Robin Laplacians with jump measures on arbitrary domains, analyzing their properties, and studying the convergence of associated semigroups.

Contribution

It introduces a capacity-based approach to define admissible measures for nonlocal Robin Laplacians on arbitrary domains, ensuring form closability and semigroup generation.

Findings

The nonlocal Robin Laplacian generates a sub-Markovian $C_0$-semigroup.

The semigroup is not dominated by the Neumann Laplacian unless the jump measure vanishes.

Semigroup convergence is characterized by vague and $\gamma$-convergence of measures.

Abstract

In this paper, we prove that it is always possible to define a realization of the Laplacian $\Delta_{\kappa,\theta}$ on $L^2(\Omega)$ subject to nonlocal Robin boundary conditions with general jump measures on arbitrary open subsets of $\mathbb R^N$. This is made possible by using a capacity approach to define admissible pair of measures $(\kappa,\theta)$ that allows the associated form $\mathcal E_{\kappa,\theta}$ to be closable. The nonlocal Robin Laplacian $\Delta_{\kappa,\theta}$ generates a sub-Markovian $C_0-$semigroup on $L^2(\Omega)$ which is not dominated by Neumann Laplacian semigroup unless the jump measure $\theta$ vanishes. Finally, the convergence of semigroups sequences $e^{-t\Delta_{\kappa_n,\theta_n}}$ is investigated in the case of vague convergence and $\gamma-$convergence of admissible pair of measures $(\kappa_n,\theta_n)$.