POSITIVE PERIODIC SOLUTIONS OF COUPLED DELAY DIFFERENTIAL SYSTEMS DEPENDING ON TWO PARAMETERS

Abstract

A coupled functional differential systems depending on two parameters is considered. It is shown that there are three mutually exclusive and exhaustive subsets Θ1, Γ and Θ2 of the parameter space such that there exist at least two positive periodic solutions associated with pairs in Θ1, at least one positive periodic solution associated with Γ and none associated with Θ2.