Local extrema of positive solutions of nonlinear functional differential equations

Abstract

We study the positive solutions of a general class of second-order functional differential equations, which includes delay, advanced, and delay-advanced equations. We establish integral conditions on the coefficients on a given bounded interval J such that every positive solution has a local maximum in J. Then, we use the connection between that integral condition and Rayleigh quotient to get a sufficient condition that is easier to be applied. Several examples are provided to demonstrate the importance of our results.