Invariant Complex Structures on Four-Dimensional Solvable Real Lie Groups.
We investigate the isometry groups of the left-invariant Riemannian and sub-Riemannian structures on simply connected three-dimensional Lie groups. More specifically, we determine the isometry group for each normalized structure and hence characterize for exactly which structures (and groups) the isotropy subgroup of the identity is contained in the group of automorphisms of the Lie group. It turns out (in both the Riemannian and sub-Riemannian cases) that for most structures any isometry is the...
We consider a family of non-unimodular rank one NA-groups with roots not all positive, and we show that on these groups there exists a distinguished left invariant sub-Laplacian which admits a differentiable functional calculus for every p ≥ 1.
Let be a symmetric space of the noncompact type, with Laplace–Beltrami operator , and let be the -spectrum of . For in such that , let be the operator on defined formally as . In this paper, we obtain operator norm estimates for for all , and show that these are optimal when is small and when is bounded below .
Le but de ce travail est de donner une description globale du caractère des représentations unitaires irréductibles d’un groupe presque algèbrique réel, construites par M. Duflo dans le cadre de la méthode des orbites. Pour ce faire, nous démontrons sous certaines conditions une formule de localisation permettant d’exprimer le caractère d’une représentation associée à l’orbite coadjointe au voisinage d’un élément elliptique en terme de la transformée de Fourier de la mesure de Liouville sur l’ensemble...