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Ali Hassani 《Comptes Rendus Mathematique》2009,347(13-14):725-728
We prove that the solutions of the homogeneous wave equation on Riemannian symmetric spaces have dispersion properties and we deduce Strichartz type estimates for these solutions. To cite this article: A. Hassani, C. R. Acad. Sci. Paris, Ser. I 347 (2009). 相似文献
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《Comptes Rendus de l'Academie des Sciences Series IIA Earth and Planetary Science》1997,324(9):1071-1074
Given a symmetric matrix A(x) = [aij(x)] depending on a parameter x, we study the second order sensitivity of all the eigenvalues λm(x) of A(x). Under some smoothness assumptions like the aij being twice differentiable, we prove that the second order directional derivatives (which naturally arise in the context of nonsmooth functions) of λm do exist, are equal, and we give their explicit expression in terms of the data of the parametrized matrix. The techniques used are quite different from those for the first order sensitivity; they rely on sharp results by G.W.Stewart concerning the perturbation of invariant subspaces. 相似文献
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Nicolas Guzy 《Comptes Rendus Mathematique》2005,341(10):593-596
In the paper by Guzy and Point, Differential topological fields, the model-completion of the theory of ordered valued differential fields is established. Models of this theory are closed ordered differential fields (the theory CODF was studied by Singer) which have a non-trivial convex (for the order) subring as valuation ring. Here we prove the valued analogue of a result of Singer: if K is a model of then () is a model of the theory of differentially closed valued fields which is the model-completion of the theory of non-trivially valued differential fields of characteristic zero. To cite this article: N. Guzy, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
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Ivan Pan 《Bulletin of the Brazilian Mathematical Society》1999,30(1):95-98
Resumé On montre que tout ensemble de générateurs du groupe de Cremona de l'espace projectif de dimension plus grande que 2 doit contenir un nombre infini non dénombrable de transformations non triviales.
We show that any set of generators of the Cremona group ofPn withn greater than 2 contains an infinite non numerable number of non trivial transformations.相似文献
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No?l Lohoué 《Monatshefte für Mathematik》2009,123(1):307-319
On montre que le spectre du laplacien d’une métrique invariante à gauche sur un groupe de Lie non compact, unimodulaire, est
un intervalle [σ, ∞] avec, éventuellement, des valeurs propres de multiplicité infinies. Dans certains cas particuliers, on montre aussi qu’il
est absolument continu; en général l’intervalle [σ, ∞] est le spectre essentiel. Cette étude a débuté pour la première fois avec le travail Furutani et al. (Commun Part Differ
Equ 18, 1993). 相似文献
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For simply connected nilpotent Lie groups, we show that a probability measure is gaussian in the sense of Bernstein (for a definition thereof which in a natural way involves non-commutativity) iff it is a gaussian measure in the classical sense concentrated on an abelian subgroup. Furthermore we carry over the Skitovic̆-Darmois theorem to symmetric spaces of non-compact type. 相似文献
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