Nontrivial solutions for superquadratic nonautonomous periodic systems

Abstract

We consider a nonautonomous second order periodic system with an indefinite linear part. We assume that the potential function is superquadratic, but it may not satisfy the Ambrosetti-Rabinowitz condition. Using an existence result for $C^1$-functionals having a local linking at the origin, we show that the system has at least one nontrivial solution.