We prove that for any λ ∈ ℝ, there is an increasing sequence of eigenvalues μₙ(λ) for the nonlinear boundary value problem ⎧ $\Delta ₚu={\left|u\right|}^{p-2}u$ in Ω, ⎨ ⎩ ${\left|\nabla u\right|}^{p-2}\partial u/\partial \nu ={\lambda \varrho \left(x\right)\left|u\right|}^{p-2}u+\mu {\left|u\right|}^{p-2}u$ on crtial ∂Ω and we show that the first one μ₁(λ) is simple and isolated; we also prove some results about variations of the density ϱ and the continuity with respect to the parameter λ.

In this paper, we study the spectrum for the following eigenvalue problem with the p-biharmonic operator involving the Hardy term: ${\Delta \left(\right|\Delta u|}^{p-2}{\Delta u)=\lambda (\left|u\right|}^{p-2}u)/\left(\delta {\left(x\right)}^{2p}\right)$ in Ω, $u\in W{₀}^{2,p}\left(\Omega \right)$. By using the variational technique and the Hardy-Rellich inequality, we prove that the above problem has at least one increasing sequence of positive eigenvalues.

Given an open set $\mathrm{\Omega }$ of ${\mathbb{R}}^N$$\left(N>2\right)$, bounded or unbounded, and a function $w\in L^{\frac{N}{2}}\left(\mathrm{\Omega }\right)$ with $w^{+}\ne 0$ but allowed to change sign, we give a short proof...

We generalize to the p-Laplacian Δp a spectral inequality proved by M.-T. Kohler−Jobin. As a particular case of such a generalization, we obtain a sharp lower bound on the first Dirichlet eigenvalue of Δp of a set in terms of its p-torsional rigidity. The result is valid in every space dimension, for every 1 < p < ∞ and for every open set with finite measure. Moreover, it holds by replacing the first eigenvalue with more general optimal Poincaré-Sobolev constants. The method of proof...