Positive Commutator Methods for Nonlinear Wave Equations. Constraints on Periods and Exponential Decay of Periodic Solutions

R.M. Pyke and I.M. Sigal Partial Differential Equations and Their Applications, edited by P. Greiner, V. Ivrii, L. Seco, and C. Sulem. Centre de Recherches Mathematiques, CRM Proceedings and Lecture Notes, Vol. 12. Published by the Americal Mathematical Society (1997).

Abstract: This article is a brief version of the paper Nonlinear Wave Equations: Constraints on Periods and Exponential Bounds for Periodic Solutions, Duke Math Journal, Vol. 88, No. 1 (1997). Here we state our results and give a general discussion on the method of proof (application of positive commutators to nonlinear equations).