Microlocalisation simultanée et problème de Cauchy ramifié
Ce travail est consacré à l’étude du problème mixte linéaire pour un système non caractéristique, strictement hyperbolique, de degré 1, dans le cas où la condition aux limites présente un saut sur une hypersurface non caractéristique du bord. Sous la condition de Lopatinski uniforme hors de cette hypersurface et sous une hypothèse supplémentaire le long de celle-ci, on prouve un résultat d’existence et d’unicité dans l’espace de Sobolev . On étudie ensuite la propagation de la régularité conormale...
We present in this text two results of long time existence for solutions of nonlinear Klein-Gordon equations, obtained through normal forms methods. In particular, we indicate how these methods allow one to obtain almost global solutions for that equation on spheres, despite the fact that such solutions do not go to zero when time goes to infinity.
This paper is devoted to the proof of almost global existence results for Klein-Gordon equations on compact revolution hypersurfaces with non-Hamiltonian nonlinearities, when the data are smooth, small and radial. The method combines normal forms with the fact that the eigenvalues associated to radial eigenfunctions of the Laplacian on such manifolds are simple and satisfy convenient asymptotic expansions.
This paper is devoted to the proof of almost global existence results for Klein-Gordon equations on compact revolution hypersurfaces with non-Hamiltonian nonlinearities, when the data are smooth, small and radial. The method combines normal forms with the fact that the eigenvalues associated to radial eigenfunctions of the Laplacian on such manifolds are simple and satisfy convenient asymptotic expansions.
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