Asymptotic behaviour of non-linear parabolic equations with monotone principal part

We consider non-linear parabolic equations with subdifferential principal part and give conditions under which they posses global attractors in spite of considering non-Lipschitz perturbations. The case of globally Lipschitz perturbations of 4 maximal monotone operator has been addressed in Boll. Un. Mat. Ital. B (8) 2 (2000) 693-706. In the case of perturbations which are not globally Lipschitz, the main difficulty is the lack of uniqueness of solutions which at first does not even allow us to define attractors. We overcome this difficulty for problems enjoying certain regularity and absorption properties that allow uniqueness of solutions after some time has been elapsed. The results developed here are applied to the case when the subdifferential operator is the p-Laplacian to obtain existence of attractors and the existence of periodic solutions. (C) 2003 Elsevier Science (USA). All rights reserved.