In his 1890 analysis of the stability of orbits in the classical three body problem, PoincarA(c) introduced basic ideas about twist maps of the annulus. One hun

This book concentrates mainly on the theorem of existence of periodic orbits for higher dimensional analogs of Twist maps. The setting is that of a discrete var

This work, consisting of expository articles as well as research papers, highlights recent developments in nonlinear analysis and differential equations. The ma