a1 Kunming University of Science and Technology Institute of Applied Mathematics of Yunnan Province Kunming, 650093 Peoples Rrepublic of China
a2 Department of Mathematics Yunnan University Institute of Applied Mathematics of Yunnan Province Kunming, 650091 Peoples Republic of China
a3 School of Mathematics and Statistics The University of Sydney Sydney, NSW 2006 Australia
This paper is concerned with finding periodic solutions of differential delay systems
where ri (i = 1, 2,…, n − 1) are positive constants. By using the theory of Hamiltonian systems, we obtain some sufficient conditions under which these systems have many periodic solutions with known periods.
(Received February 04 1999)