-approximation of generalized biaxially symmetric potentials over Carathéodory domains
In ipotesi molto generali si dimostrano teoremi di completezza nel senso di Picone per l'equazione (1). Come corollario si ottengono teoremi del tipo Runge.
It is proved that Lopatinskii's condition is necessary and sufficient for problem (2.5) to be an index problem. A method is given for the determination of the index.
Let be a long range metric perturbation of the Euclidean Laplacian on , . We prove local energy decay for the solutions of the wave, Klein-Gordon and Schrödinger equations associated to . The problem is decomposed in a low and high frequency analysis. For the high energy part, we assume a non trapping condition. For low (resp. high) frequencies we obtain a general result about the local energy decay for the group where has a suitable development at zero (resp. infinity).
We give sufficient conditions for the existence of global small solutions to the quasilinear dissipative hyperbolic equation corresponding to initial values and source terms of sufficiently small size, as well as of small solutions to the corresponding stationary version, i.e. the quasilinear elliptic equation We then give conditions for the convergence, as , of the solution of the evolution equation to its stationary state.