Generalized nonlocal Robin Laplacian on arbitrary domains

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 an 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 the Neumann Laplacian semigroup unless the jump measure \(\theta \) vanishes.