Uniqueness results for the exterior Dirichlet and Neumann problem in two dimensions for the Euler-Lagrange equations of variational integrals with linear growth

Abstract

We consider solutions $u, v:Ω\rightarrow\mathbb{R}^{N}$ of the Euler-Lagrange equations associated to the variational integral $\int_Ωf(\nabla u)dx$, where $Ω$ is an exterior domain in $\mathbb{R}^{2}$ e.g., the complement of a disk or a half plane, and the density $f$ is of linear growth. Among other things we show that $u|_{\partialΩ}=v|_{\partialΩ}$ together with the boundedness of $u-v$ yields that $u=v$ on the entire domain.