Periodic Solutions to a Type of Neutral Integro-DifferentialEquation with Three Delays
多时滞中立型微分积分方程的周期解

The existence of periodic solutions to the neutral integro-differential equation $x'(t)=\int^t_{t-\sigma}g\big{(}t, s, x(s)\big{)}{\mathrm{d}}s+ f\big{(}t, x(t-\tau_0), x'(t-\tau_1)\big{)}$ with three delays is studied, the sufficient conditions of the existence of periodic solutions to the equations is obtained. The result shows the influence of the lag $\sigma$ to the existence of periodic solutions.