“…Nonetheless, by KAM theory, near such elliptic orbits there exists a positive measure set foliated by KAM-tori that corresponds to trajectories which remain forever near the elliptic trajectory. Furthermore, while other trajectories in this neighborhood may perhaps escape, this can take exponentially long time [18,7] (namely, such islands may correspond to highdimensional dynamical traps, generalizing the 2d stickiness phenomena). Thus, hereafter, an island in the multi-dimensional context will be defined as the small neighborhood of the elliptic orbit which is effectively stable [7], bearing in mind that only in the two degrees of freedom case this neighborhood is known to correspond to an invariant set.…”