Boundedness for impulsive delay differential equations and applications to population growth models

In this paper, criteria on uniform ultimate boundedness are derived for impulsive delay differential equations using Lyapunov functions and Razumikhin techniques. It should be noted that the boundedness criteria establish global existence of solutions as well as boundedness without assuming, a priori, that solutions can necessarily be continued to infinity. Those criteria are then used to obtain permanence results for population growth models. Some examples are discussed to illustrate the theorems. (C) 2003 Elsevier Science Ltd. All rights reserved.