Existence results for gradient elliptic systems with nonlinear boundary conditions

Abstract

We prove the existence of nontrivial solutions to the system Δpu = |u|p-2u, Δqv = |v| q-2v, on a bounded set of ℝN, with nonlinear coupling at the boundary given by |∇u|p-2∂u/∂ν = F u(x, u, v), |∇u|q-2∂v/∂ν = F v(x, u, v). The proofs are done under suitable assumptions on the potential F, and based on variational arguments. Our results include subcritical, resonant and critical growth on F.