Almost periodic solutions of second-order systems with monotone fields on a compact subset Original Research Article

We give sufficient conditions for the existence of almost periodic solutions of the second-order differential system: u″=F(t,u), when View the MathML source with K is a compact convex subset of View the MathML source, and the partial function F(t,.) is monotone for each View the MathML source. For existence, we do not assume that F(t,.) is strictly monotone.