Investigation for periodic and almost periodic solutions of first-order ordinary differential equations

Approaches to estimating for the number of periodic and almost periodic solutions of ordinary differential equations are considered. Conditions that allow determinating both the upper and lower bounds for these solutions are found. The existence of periodic and almost periodic solutions in problems are considered. Approaches to estimating for the number of periodic solutions of ordinary differential equations are considered. Conditions that allow determinating both the upper and lower bounds for these solutions are found. The existence and stability of almost periodic problems are considered.