Existencia de soluciones débiles para problemas elípticos semilineales.

Abstract

In this paper we analyze the multiplicity of the weak, non-trivial solutions of elliptic semilinear problems with indefinite weight, in a bounded domain of ℝ^N, con N ≥3, with homogeneous Neumann boundary conditions. Specifically, we study the equation -div(h(x) ∇u) +q(x)=λ w(x)f(u),, where $h$ satisfies the ellipticity conditions, q is a nonnegative function at almost every point in the domain and w a function that changes sign and, whose data is nonlinear, presents a superlinear and subcritical growth.

By means of variational techniques, such as the direct methods of variational calculus and the minimax theorems, in particular; the mountain pass theorem and a Linking theorem, will be obtained depending on the growth of f and the parameter λ, results of existence and at least two different solutions will be found.