Déformations isospectrales sur certaines nilvariétés et finitude spectrale des variétés de Heisenberg
Degree theory for VMO maps on metric spaces
We construct a degree theory for Vanishing Mean Oscillation functions in metric spaces, following some ideas of Brezis & Nirenberg. The underlying sets of our metric spaces are bounded open subsets of and their boundaries. Then, we apply our results in order to analyze the surjectivity properties of the -harmonic extensions of VMO vector-valued functions. The operators we are dealing with are second order linear differential operators sum of squares of vector fields satisfying the hypoellipticity...
Die Existenz einer Lévy-Abbildung auf einem homogenen Raum.
Die Resolvente von ... Auf symmetrischen Räumen vom nichtkompakten Typ.
Differential operators on equivariant vector bundles over symmetric spaces.
Dirichlet forms on symmetric spaces
Let be a locally compact group and a compact subgroup such that the algebra of biinvariant integrable functions is commutative. We characterize the -invariant Dirichlet forms on the homogeneous space using harmonic analysis of . This extends results from Ch. Berg, Séminaire Brelot-Choquet-Deny, Paris, 13e année 1969/70 and J. Deny, Potential theory (C.I.M.E., I ciclo, Stresa), Ed. Cremonese, Rome, 1970. Every non-zero -invariant Dirichlet form on a symmetric space of non compact type...
Discrepancy convergence for the Drunkard's walk on the sphere.
Distances hilbertiennes invariantes sur un espace homogène
Nous déterminons pour certains espaces homogènes les distances invariantes qui proviennent d’un plongement de dans un espace de Hilbert. Le carré d’une telle distance est un noyau de type négatif invariant dont nous donnons une représentation, c’est la formule de Lévy-Kinchine. Nous en déduisons que si possède la propriété (T) de Kajdan une telle distance est toujours bornée.
Distributions coniques sur le cône des matrices de rang un et de trace nulle
Distributions homogènes sur une algèbre de Jordan
Distributions sphériques et équations différentielles singulières
Ditkin sets in homogeneous spaces
Ditkin sets for the Fourier algebra A(G/K), where K is a compact subgroup of a locally compact group G, are studied. The main results discussed are injection theorems, direct image theorems and the relation between Ditkin sets and operator Ditkin sets and, in the compact case, the inverse projection theorem for strong Ditkin sets and the relation between strong Ditkin sets for the Fourier algebra and the Varopoulos algebra. Results on unions of Ditkin sets and on tensor products are also given.
Divergent trajectories of flows on homogeneous spaces and Diophantine approximation.