Existence and Multiplicity Results for a Non Linear Hammerstein Integral Equation.

In this paper we study the solvability of a nonlinear Hammerstein integral equation by using a variational principle of B. Ricceri and methods of critical point theory. In particular we do not require any positivity assumption on the kernel of the equation. Our results can be applied to higher order elliptic boundary value problem with changing sign kernel. [ABSTRACT FROM AUTHOR]