Positive periodic solutions of functional differential equations and population models

Abstract

In this paper, we employ Krasnosel'skii's fixed point theorem for cones to study the existence of positive periodic solutions to a system of infinite delay equations, x?(t) = A(t)x(t) + f(t,xt). We prove two general theorems and establish new periodicity conditions for several population growth models. © 2002 Southwest Texas State University.