Periodic Solutions of Differential and Difference Systems with Pendulum-Type Nonlinearities: Variational Approaches

Abstract

We survey some recent results on the use of variational methods in proving the existence and multiplicity of periodic solutions of systems of differential equations of the type (Formula presented.) or systems of difference equations of the type (Formula presented.) when φ belongs to a class of suitable homeomorphisms between an open ball and the whole space and F is periodic in the components of q. © Springer Science+Business Media New York 2013.