Almost periodic solutions of monotone second-order differential equations
Résumé
We give sufficient conditions for the existence of almost periodic solutions of the following second-order differential equation: u′′(t) = f(u(t)) + e(t) on a Hilbert space H, where the vector field f : H −→ H is monotone, continuous and the forcing term e : R −→ H is almost periodic. Notably, we state a result of existence and uniqueness of the Besicovitch almost periodic solution, then we approximate this solution by a sequence of Bohr almost periodic solutions.