Espace de Hardy pour les quotients \Gamma \backslash G

Résumé. Soit G un groupe linéaire réel simple hermitien, un sous-groupe arithmétique de covolume fini. Soit C un c?ne régulier Ad(G)-invariant dans l'algèbre de Lie de G, l'intérieur de C, et S(C)=Gexp(iC) le semi-groupe complexe d'Olshanski. L'espace de Hardy associéà ces données est l'espace des fonctions holomorphes sur , -invariantes à gauche telles qu'une certaine norme soit finie. C'est un espace de Hilbert, qui se plonge de manière isométrique dans l'espace . On donne une décomposition de l'espace de Hardy en représentations unitaires irréductibles avec des multiplicités égales à des dimensions d'espaces de formes automorphes. Les résultats les plus importants sont obtenus dans le cas de et , où l'on démontre que l'espace des vecteurs distributions des représentations de la série discrète, qui sont -invariants et qui vérifient une condition de carré intégrabilité, s'identifie à l'espace des formes modulaires paraboliques correspondant, ce qui nous permet de décrire explicitement la décomposition de l'espace de Hardy cuspidal en représentations irréductibles et d'en calculer le noyau reproduisant (appelé noyau de Cauchy-Szeg?) à l'aide des noyaux reproduisants des espaces de cusp forms. L'espace de Hardy cuspidal s'identifie au “morceau holomorphe” du spectre cuspidal .

---

Received April 30, 1997; in final form September 18, 1997     

Représentations du groupe des tresses généralisées dans des groupes de Lie

Let Γ be a Lie group.Then any automorphism of the free group of rank n induces a diffeomorphism of Γ ⁿ . We use this remark and a result of P. Vogel to construct linear representations of a certain automorphism group of the algebraic closure of the free group. This automorphism group is closely related to the string link cobordism group.

Received:     

Limiting angles of Γ-martingales

Suppose that M is a complete, simply connected Riemannian manifold of non-positive sectional curvature with dimension m≥ 3 and that, outside a fixed compact set, the sectional curvatures are bounded above by −c ₁/{r ² ln r} and below by −c ₂ r ², where c ₁ and c ₂ are two positive constants and r is the geodesic distance from a fixed point. We show that, when κ≥ 1 satisfies certain conditions, the angular part of a κ-quasi-conformal Γ-martingale on M tends to a limit as time tends to infinity and the closure of the support of the distribution of this limit is the entire sphere at infinity. This improves both a result of Le for Brownian motion and also results concerning the non-existence of κ-quasi-conformal harmonic maps from certain types of Riemannian manifolds into M. Received: 19 September 1997     

Remarques sur les m\'ethodes de projection pour l'approximation des \'equations de Navier--Stokes

Summary. L'objet de cet article est de montrer que les estimations de convergence sur la pression pour les m\'ethodes de projection d\'ecrites dans \cite{Shen1} et \cite{Shen2} ne sont pas obtenues correctement car elles sont toutes bas\'ees sur une in\'egalit\'e fausse. Il semble qu'on ait besoin d'une convergence en de la vitesse dans pour d\'emontrer les estimations de convergence sur la pression en . La question de savoir si la m\'ethode de projection a un taux de convergence pour la pression plus \'elev\'e que reste ouverte. Received June 1, 1993     

Sur un problème de prolongement des fonctions plurisousharmoniques dont la masse de Riesz est localement finie le long d'un obstacle fermé

In this paper, we prove sufficient conditions of extension for plurisubharmonic functions, using potential theory methods. Received: 7 November 1997 / Revised version: 15 July 1998     

Pôles de∫ A f s • pour une singularité presque isolée

Let be a germ of real analytic function (n≥ 1). We suppose that the complexified germ has an almost isolated singularity at 0 for an eigenvalue of the monodromy . Denote by A a linear combination of the connected components of . The purpose of this paper is to give a necessary and sufficient condition such that the distribution admits a sequence of poles in . Received: 18 July 1996 / Revised version: 13 May 1998     

Certain classes of pluricomplex Green functions on ${\mathbb C}^n$

We consider (pluricomplex) Green functions defined on , with logarithmic poles in a finite set and with logarithmic growth at infinity. For certain sets, we describe all the corresponding Green functions. The set of these functions is large and it carries a certain algebraic structure. We also show that for some sets no such Green functions exist. Our results indicate the fact that the set of poles should have certain algebro-geometric properties in order for these Green functions to exist. Received November 24, 1998; in final form April 19, 1999 / Published online July 3, 2000     

Note on conjectures of Beilinson–Bloch–Kato¶for cycle classes

Conjecures of Beilinson and Bloch–Kato describe the order of zeros of L-functions of motives in terms of motivic cohomology groups and Selmer groups. We restrict our attention to the parts generated by the cycle classes, and give modest evidence for the conjectures. Received: 7 June 1999 / Revised version: 7 September 1999     

Surfaces tendues dans \mbox{{\bf E}^{3}}: des théorèmes de structure

Sans résumé

---

Re?u le 13 February 1997     

Characterizations of G-tube domains

Let G be a real connected Lie group for which the universal complexification G ^ℂ has a polar decomposition G ^ℂ≅G exp(i?), where ? denotes the Lie algebra of G. The present paper is concerned with Riemann G-domains over the complex group G ^ℂ viewed as a G-manifold via the left multiplication. Such a Riemann domain X is said to be of Reinhardt type if G contains a discrete cocompact subgroup $\Gamma$ for whichG/Γ is a Stein manifold. Here the following is proved: Every Riemann G-domain of Reinhardt type is schlicht, hence a G-tube domain, i.e., a G-invariant subdomain of G ^ℂ. As an application one obtains conditions for a holomorphically separable G-manifold to be a G-tube domain. Received: 22 October 1998     

Duality methods with an automatic choice of parameters Application to shallow water equations in conservative form

Summary.   In [3] a duality numerical algorithm for solving variational inequalities based on certain properties of the Yosida approximation of maximal monotone operators has been introduced. The performance of this algorithm strongly depends on the choice of two constant parameters. In this paper, we consider a new class of algorithms where these constant parameters are replaced by functions. We show that convergence properties are preserved and look for optimal values of these two functions. In general these optimal values cannot be computed, as they depend on the exact solution. Therefore, we propose some strategies in order to approximate them. The resulting algorithms are applied to three variational inequalities in order to compare their performance with that of the original algorithm. Received July 20, 1998 / Revised version received November 26, 1999 / Published online February 5, 2001