Alexandru Kristály

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We propose a direct approach for detecting arbitrarily many solutions for perturbed elliptic problems involving oscillatory terms. Although the method works in various frameworks, we illustrate it on the problem ⎪⎨ ⎪⎩ − u+ u=Q(x)[f (u)+ εg(u)], x ∈RN, N 2, u 0, u(x)→ 0 as |x| →∞, (Pε) where Q :RN →R is a radial, positive potential, f : [0,∞)→R is a(More)
Let (M, g) be a compact Riemannian manifold without boundary, with dimM ≥ 3, and f : R→ R a continuous function which is sublinear at infinity. By various variational approaches, existence of multiple solutions of the eigenvalue problem −∆gω + α(σ)ω = K̃(λ, σ)f(ω), σ ∈M, ω ∈ H 1 (M), is established for certain eigenvalues λ > 0, depending on further(More)
In this paper we prove the principle of symmetric criticality for Motreanu–Panagiotopoulos type functionals, i.e., for convex, proper, lower semicontinuous functionals which are perturbed by a locally Lipschitz function. By means of this principle a variational–hemivariational inequality is studied on certain type of unbounded strips. © 2006 Elsevier Inc.(More)
Some multiplicity results are presented for the eigenvalue problem { −div(|x|−2a∇u)= λ|x|−2bf (u)+μ|x|−2cg(u) in Ω, u= 0 on ∂Ω, (Pλ,μ) where Ω ⊂Rn (n 3) is an open bounded domain with smooth boundary, 0 ∈Ω , 0 < a < n−2 2 , a b, c < a + 1, and f :R→R is sublinear at infinity and superlinear at the origin. Various cases are treated depending on the behaviour(More)
In this paper we study the multiplicity of solutions for a class of eigenvalue problems for hemivariational inequalities in strip-like domains. The first result is based on a recent abstract theorem of Marano and Motreanu, obtaining at least three distinct, axially symmetric solutions for certain eigenvalues. In the second result, a version of the fountain(More)
We extend a recent result of Ricceri concerning the existence of three critical points of certain non-smooth functionals. Two applications are given, both in the theory of differential inclusions; the first one concerns a non-homogeneous Neumann boundary value problem, the second one treats a quasilinear elliptic inclusion problem in the whole RN .
We construct a constrained trivariate extension of the univariate normalized B-basis of the vector space of trigonometric polynomials of arbitrary (finite) order n ∈ N defined on any compact interval [0, α], where α ∈ (0, π). Our triangular extension is a normalized linearly independent constrained trivariate trigonometric function system of dimension δn =(More)