On the conditions for the hyperbolicity of systems with double characteristic roots. I. (English) Zbl 0471.35052
MSC:
35L45 | Initial value problems for first-order hyperbolic systems |
35B30 | Dependence of solutions to PDEs on initial and/or boundary data and/or on parameters of PDEs |
35A30 | Geometric theory, characteristics, transformations in context of PDEs |