QUALITATIVE PROPERTIES FOR SOME NONLINEAR HIGHER ORDER DEGENERATE PARABOLIC EQUATIONS

Abstract. We prove that if 1 < q < p the "energy solutions " of 0 [q_ • u) + ( 1) • Z D • ([D•ulp-•sgnD•u) f 7 (lu sgn-----have finite speed of propagation. For p-- 2 the second term is (-A)"•u. We also study upper and lower bounds of the interface (or free boundary), decay rates as t-- • c•, extinction in finite tinhe, nonexistence of non-negative solutions and some generalizations to other equations