Transformation de Fourier sphérique de type
We develop methods for studying transition operators on metric spaces that are invariant under a co-compact group which acts properly. A basic requirement is a decomposition of such operators with respect to the group orbits. We then introduce reduced transition operators on the compact factor space whose norms and spectral radii are upper bounds for the Lp-norms and spectral radii of the original operator. If the group is amenable then the spectral radii of the original and reduced operators coincide,...
Given that a connected Lie group with nilpotent radical acts transitively by isometries on a connected Riemannian manifold , the structure of the full connected isometry group of and the imbedding of in are described. In particular, if equals its derived subgroup and its Levi factors are of noncompact type, then is normal in . In the special case of a simply transitive action of on , a transitive normal subgroup of is constructed with and a sufficient condition is given...
We introduce an explicit procedure to generate natural operators on manifolds with almost Hermitian symmetric structures and work out several examples of this procedure in the case of almost Grassmannian structures.
We show that each element in the semigroup of all non-singular upper (or lower) triangular stochastic matrices is generated by the infinitesimal elements of , which form a cone consisting of all upper (or lower) triangular intensity matrices.
De même qu’avec les groupes de Lie, à tout pseudo-groupe infinitésimal de Lie sur il est associé de façon naturelle une algèbre de Lie , qui est une sous-algèbre de Lie fermée de l’algèbre de Lie de tous les champs de vecteurs formels de , l’algèbre étant munie de la topologie définie par la filtration naturelle de l’algèbre des séries formelles. Le troisième théorème fondamental de Cartan dit qu’inversement étant donnée une sous-algèbre de Lie transitive fermée de l’algèbre , il existe...
We consider a real analytic dynamical system G×M→M with nonempty fixed point subset M G. Using symmetries of G×M→M, we give some conditions which imply the existence of transitive Lie transformation group with G as isotropy subgroup.