On Invariant Closed Curves for One-Step Methods.
This paper is concerned with square integrable quasi-derivatives for any solution of a general quasi-differential equation of th order with complex coefficients , provided that all th quasi-derivatives of solutions of and all solutions of its normal adjoint are in and under suitable conditions on the function .
We prove several results on lower bounds for the periods of periodic solutions of some classes of functional-differential equations in Hilbert and Banach spaces and difference inclusions in Hilbert spaces.
We obtain conditions for existence and (almost) non-oscillation of solutions of a second order linear homogeneous functional differential equations without the delay conditions , , and