On traces of functions in W-2.p(Omega) for Lipschitz domains in R-3

We consider the problem of the characterization of the range of the trace o perator (gamma, gamma (1)) : W-2.P(Omega) --> R, p is an element of ]1, inf inity[, defined by the mapping u bar right arrow (u(\Gamma),partial derivat iven(u)), when Omega is a Lipschitz. bounded subset of R-3. R turns out to be a subspace of W-1,W-p(Gamma) x L-p(Gamma). To this aim we need to prove a suitable Hedge decomposition for vector fields belonging to L-p(curl, Ome ga), and also to study some properties of the tangential gradient del (Gamm a) on a Lipschitz orientable manifold. (C) 2001 Academie des sciences/Editi ons scientifiques et medicales Elsevier SAS.