An extremal eigenvalue problem for the Wentzell-Laplace operator

We consider the question of giving an upper bound for the first nontrivial\neigenvalue of the Wentzell-Laplace operator of a domain $\\Omega$, involving\nonly geometrical informations. We provide such an upper bound, by generalizing\nBrock's inequality concerning Steklov eigenvalues, and we conjectu... View More