Existence of Periodic Solutions of Nonlinear Boundary Value Problems and the Method of Upper and Lower Solutions
Abstract
**Please note that the full text is embargoed** ABSTRACT: We study the existence of periodic solutions of second order nonlinear differential equations by combining the method of upper and lower solutions and the method of Alternative problems. Besides including previous results of other authors, we obtain criteria which are easily verifiable. These criteria are in a form that
they can be adapted for partial differential equations of parabolic and elliptic type.