REVIEW OF SOME RECENT RESULTS IN PERTURBATION THEORY FOR SOLITARY WAVES

The purpose of this review is to present some recent results in the perturbation theory of solitary waves. Results for integrable and non integrable systems are visited. The examples are from different fields of application. Some of the examples concerning the interaction of solitons and radiation are discussed in more detail. Also ideas which could be of wider applicability are developed. Unsolved probiems are presented and the status of rigorous results relevant to perturbation theory is also discussed.