The general method for solving of the boundary problems for the partial differential equations of any order II
L’auteur prouve deux théorèmes d’unicité locale du problème de Cauchy pour des opérateurs linéaires de symboles principaux réels. Il se place dans le cas où possède des points critiques réels (), au voisinage desquels il suppose une condition faible de “pseudo-convexité” (au sens d’Hörmander). Il donne alors des conditions sur le symbole sous-principal de l’opérateur qui assurent l’unicité.
L'autore dà una condizione necessaria e sufficiente per la risolubilità formale degli operatori differenziali a coefficienti costanti, lineari, , in termini di prolungamento, come distribuzioni, delle , tali che .
Let be a order differential operator in a hermitian vector bundle over a compact riemannian manifold with boundary ; and denote by the realization defined by a normal differential boundary condition (, Cauchy data). We characterize, by an explicit condition on and near , the realizations for which there exists an integro-differential sesquilinear form on such that on ; moreover we show that these are exactly the realizations satisfying a weak semiboundedness estimate:...