Stelmaschuk L. The periodic solutions for differential equations with delay

The thesis deals with investigation of the problem of construction of periodic solutions for autonomous differential equations with delay and new classes of nonlinear integral-differential equations with delay. Algorythm of construction of periodic solutions for autonomous differential equations with delay based on numerical-analytic method by A.M.Samoilenko is proposed and proved here. Evaluations for fault of method are found and sufficient conditions for existence of periodic solutions for these equations are investigated. Specialities of linear replacement of variables to transform autonomous system with delay into nonautonomous system are studied. For integral - differential equations with delay with integral member by Voltera's type sufficient conditions for coinsidence which contain value of delay in obvious form are received. The scheme of investigation of periodic solutions for integral-differential equations with delay for T-systems of first and second classes is studied.