B. Messirdi, A. Rahmani, A. Senoussaoui 
Conditions necessaires et suffisantes pour qu'un problème de Cauchy C^{ } soit bien posé ... 
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ABSTRACT.  The objectif of this paper is to establish, with using localization hypothesis, some algebrically conditions of well decomposition of a system of partial differential equations with multiple characteristics and pair multiplicity. These conditions are sufficient for the well posendness of the C^{ } associated Cauchy problem. The technic of the asymptotically solutions prove that these sufficient conditions are also necessary.