On Positive Periodic Solution for Neutral Delay Model

Abstract:

      In this paper,by using theory of topological degree and some new techniques,the existence of a positive periodic solution of the neutral delay model N′(t)=N(t)［a(t)-b(t)N(t-τ(t))-c(t)N′(t-τ(t))］is studied. A new result is obtained. An open question is answered,and results in some known references are extended and improved. In addition,mistake of a differential operation and Theorem 2 in ［3］ is corrected.