Saddle type solutions for a class of reversible elliptic equations

Abstract

This paper is concerned with the existence of saddle type solutions for a class of semilinear elliptic equations of the type \begin{equation} \Delta u(x)+F_{u}(x,u)=0,\quad x\in\mathbb R^{n},\;\; n\ge 2, \tag*{(PDE)} \end{equation} where $F$ is a periodic and symmetric nonlinearity. Under a non degeneracy condition on the set of minimal periodic solutions, saddle type solutions of $(PDE)$ are found by a renormalized variational procedure.