Positive Periodic Solutions of Second-Order Differential Equations with Delays

Abstract EN

The existence results of positive ω-periodic solutions are obtained for the second-order differential equation with delays −u″+a(t)=f(t,u(t−τ1),...,u(t−τn)), where a∈C(ℝ,(0,∞)) is a ω-periodic function, f:ℝ×[0,∞)n→[0,∞) is a continuous function, which is ω-periodic in t, and τ1,τ2,...,τn are positive constants.

Our discussion is based on the fixed point index theory in cones.