Positive Periodic Solutions Of A Fourth Order Differential Equation With Periodic Boundary Value Conditions

This discussion devote to the existence of positive periodic solution for forth-order differential equation with periodic boundary conditions. We first present the Green's func-tion of linear forth-order differential equations with periodic boundary conditions, and then by using Green's function we obtain the corresponding nonlinear differential equa-tions. Moreover, we also get the existence of positive periodic solution for forth-order time-varying nonlinear differential equation.