"This study investigates the qualitative behaviour of hybrid systems... This evolution is described by the coupling of the dynamics of an ODE and that of an automaton. Once the continuous state reaches a prescribed set S, the state of the automaton switches to another state and another ODE is activated. The main theme is the characterization of periodic behaviour of such systems and, when it is obtained, the study of its stability... This mongraph is an exploration, and its merit is to convince the reader of the difficulty and richness of the topic under investigation." -Zentralblatt Math