Let M be a compact m-dimensional Riemannian manifold,let d denote its diameter,-R(R>0) the lower bound of the Ricci curvature,and λ1 the first eigenvalue for t
In this paper,the existence of nonconstant oscillating periodic solution of differential difference e-quation with n time lags is stutied:x′(t)=-g(x(t))[f(x(t-