Modern Introduction to Mathematical Analysis

He obtained two prizes from the Académie Royale de Belgique for his monographs "Periodic solutions of scalar second order differential equations with a singularity" in 1993 and "Playing around resonance. An invitation to the search of periodic solutions for second order ordinary differential equations" in 2017.

He has been invited to give plenary lectures at several conferences in Europe and in the USA.

His research interests are mainly concentrated on existence and multiplicity problems for boundary value problems. He recently gave an important contribution to the study of the periodic problem for Hamiltonian systems by providing some generalizations of the Poincaré-Birkhoff Theorem in higher dimensions. He also studied problems related to differential inclusions, persistence in dynamical systems, and global behaviour of the solutions to planar systems.