We study the existence of solutions for a p-biharmonic problem with a critical Sobolev exponent and Navier boundary conditions, using variational arguments. We establish the existence of a precise interval of parameters for which our problem admits a nontrivial solution.

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...

We consider the existence of positive solutions of -pu=g(x)|u|p-2u+h(x)|u|q-2u+f(x)|u|p*-2u(1) in ${ℝ}^N$, where $\lambda ,\alpha \in ℝ$, $1<p<N$, $p^{*}=Np/(N-p)$, the critical Sobolev exponent, and $1<q<p^{*}$, $q\ne p$. Let ${\lambda }_1^{+}>0$ be the principal eigenvalue of -pu=g(x)|u|p-2u    in ,        g(x)|u|p>0, (2) with $u_1^{+}>0$ the associated eigenfunction. We prove that, if ${\int }_{{ℝ}^N}f{\left|u_1^{+}\right|}^{p^{*}}<0$, ${\int }_{{ℝ}^N}h{\left|u_1^{+}\right|}^q>0$ if $1<q<p$ and ${\int }_{{ℝ}^N}h{\left|u_1^{+}\right|}^q<0$ if $p<q<p^{*}$, then there exist ${\lambda }^{*}>{\lambda }_1^{+}$ and ${\alpha }^{*}>0$, such that for $\lambda \in [{\lambda }_1^{+},{\lambda }^{*})$ and $\alpha \in [0,{\alpha }^{*})$, (1) has at least one positive solution.

In recent papers Ruhe suggested a rational Krylov method for nonlinear eigenproblems knitting together a secant method for linearizing the nonlinear problem and the Krylov method for the linearized problem. In this note we point out that the method can be understood as an iterative projection method. Similarly to the Arnoldi method the search space is expanded by the direction from residual inverse iteration. Numerical methods demonstrate that the rational Krylov method can be accelerated considerably...

For $0<p-1<q$ and either $ϵ=1$ or $ϵ=-1$, we prove the existence of solutions of $-{\Delta }_{p}u=ϵu^q$ in a cone $C_S$, with vertex 0 and opening $S$, vanishing on $\partial C_S$, of the form $u\left(x\right)={\left|x\right|}^{-\beta }\omega (x/\left|x\right|)$. The problem reduces to a quasilinear elliptic equation on $S$ and the existence proof is based upon degree theory and homotopy methods. We also obtain a nonexistence result in some critical case by making use of an integral type identity.