Comportement asymptotique du mouvement brownien sur une variété homogène à courbure négative ou nulle
Conal orders on homogeneous spaces.
Conformal deformations of the Riemannian metrics and homogeneous Riemannian spaces
In this paper we investigate one-dimensional sectional curvatures of Riemannian manifolds, conformal deformations of the Riemannian metrics and the structure of locally conformally homogeneous Riemannian manifolds. We prove that the nonnegativity of the one-dimensional sectional curvature of a homogeneous Riemannian space attracts nonnegativity of the Ricci curvature and we show that the inverse is incorrect with the help of the theorems O. Kowalski-S. Nikčevi'c [K-N], D. Alekseevsky-B. Kimelfeld...
Connexions et martingales dans les groupes de Lie
Constant Jacobi osculating rank of
In this paper we obtain an interesting relation between the covariant derivatives of the Jacobi operator valid for all geodesic on the flag manifold . As a consequence, an explicit expression of the Jacobi operator independent of the geodesic can be obtained on such a manifold. Moreover, we show the way to calculate the Jacobi vector fields on this manifold by a new formula valid on every g.o. space.
Construction of BGG sequences for AHS structures
This paper gives a description of a method of direct construction of the BGG sequences of invariant operators on manifolds with AHS structures on the base of representation theoretical data of the Lie algebra defining the AHS structure. Several examples of the method are shown.
Contact and equivalence of submanifolds of homogeneous spaces
Contact homogeneity and envelopes of Riemannian metrics.
Contact Lie algebras of vector fields on the plane.
Contraction semigroups and representations.
Correction to the paper “Compact fiberings of homogeneous spaces. I”
Correction to the paper: Homogeneous Einstein metrics on Stiefel manifolds
Courbure et sous-ensembles de courbes rectifiables dans le groupe de Heisenberg
Nous présentons une condition suffisante pour qu’un compact dans le groupe de Heisenberg (muni de sa structure de Carnot-Carathéodory) soit contenu dans une courbe rectifiable. Cette condition est aussi nécessaire dans le cas de courbes régulières (en particulier, des géodésiques) et elle est inspirée du lemme géométrique faible du à Peter Jones dans le cas euclidien. Cette note repose sur l’exposé fait par le troisième auteur (au Séminaire X-EDP) et décrit les principaux résultats de l’article...
Criterion for proper actions on homogeneous spaces of reductive groups.
Curvature homogeneity of affine connections on two-dimensional manifolds
Curvature homogeneity of (torsion-free) affine connections on manifolds is an adaptation of a concept introduced by I. M. Singer. We analyze completely the relationship between curvature homogeneity of higher order and local homogeneity on two-dimensional manifolds.
Curvature homogeneous riemannian manifolds
Curvature homogeneous spaces whose curvature tensors have large symmetries
We study curvature homogeneous spaces or locally homogeneous spaces whose curvature tensors are invariant by the action of “large" Lie subalgebras of . In this paper we deal with the cases of
Curvature of a semi-direct extension of a Heisenberg type nilpotent group
Curvature of lift spaces
Curvature on reductive homogeneous spaces.