2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62703We generalize to higher dimension results of Birkhoff and Mather on the existence of orbits wandering in regions of instability of twist maps. This generalization is strongly inspired by the one already proposed by Mather. However, its advantage is that it really contains most of the results of Birkhoff and Mather on twist maps.Dynamical SystemsMathematical Physics37J50,35F20text