On retarded differential equations with impulses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Processo FAPESP: 97/11323-0

We are concerned with the effect of impulses in retarded functional differential equations. By using fixed point techniques we prove the existence of periodic solutions of some impulsive equations. For a system of retarded differential equation it is shown that an impulsive self-supporting condition can play the role of a dissipative term in order to assure the existence of a convex bounded positively invariant set.