ABSTRACT:

In quasi-integrable symplectic maps it is possible to detect numerically the structure of the Arnold web, as well as a very slow diffusion with the characteristics of Arnold diffusion. The computation of the stable/unstable manifolds related to the resonances of these systems shows analogies with the a priori unstable ones, because in both cases it is the spread of these manifolds which produces the diffusion process, as well as properties which are specific of quasi-integrable systems, such as the exponential decay of the lobes of the asymptotic manifolds and of diffusion.