Groupoïdes quantiques

The aim of this paper is to introduce a notion of quantum groupoid, non-commutative analogue of Lie groupoids. This notion generalizes simultaneously the notion of a Hopf bigebroid [Mal] (corresponding to a quantum groupoid with commutative space of units) and the notion of a braided quantum group of Majid [Maj]. The commutativity hypothesis of the base in [Mal] is no more necessary and a construction of L. Vainerman [V] enters in this frame.     

Dualité pour les groupes de type multiplicatif sur certains corps de fonctions

Let K be the function field of a smooth projective curve X over a higher-dimensional local field k. We define Tate–Shafarevich groups of a commutative group scheme via cohomology classes locally trivial at each completion of K coming from a closed point of X. In this note, we state and sketch the proof of an arithmetic duality theorem for Tate–Shafarevich groups of groups of multiplicative type over K (and more generally of some two-term complexes of tori over K).     

Un résultat de stabilité pour les solutions faibles des équations des fluides tournants

We study the limit of the periodic, incompressible, rotating fluid equations, as the Coriolis force goes to infinity: in the case of well-prepared initial data in L², the weak solutions converge to the solution of a two-dimensional, incompressible Navier-Stokes equation. We also prove that the rotating fluid equations are globally well-posed under an appropriate assumption on the oscillating part of the initial data.     

Solutions en dualité pour les gaz sans pression

We introduce the notion of duality solution for the system of pressureless gases, which ensures existence for the Cauchy problem, and uniqueness under optimal conditions on initial data.     

Indépendance conditionnelle et uniformité pour les lois fortes des grands nombres dans les espaces de Banach

Summary A. Beck has given an uniform strong law of large numbers for families of mutually symmetric and uniformly essentially bounded sequences of centered random variables, with values in (k, )—B-convex spaces. We show that, without any limitation on the Banach spaces, the technique used by A. Beck allows to replace, in strong law of large numbers making use of conditions bearing on essential bounds, the hypothesis of independence by an hypothesis called conditional-independence-and-centering, which is weaker than both hypothesis of independence and of mutual symmetry; moreover, in several cases, one gets uniform strong laws of large numbers (for families of conditionally-independent-and-centered sequences). The results we get are compared with recent results of G. Pisier, obtained with type p spaces techniques.     

Sur quelques limites pour les modules des zéros des polynomes

Sans résumé     

Loi fonctionnelle du logarithme itéré pour les incréments du processus des espacements

Let a_n(l): 0 ≤ /denote the reseated empirical process based upon uniform spacings. Let {h_n, n ≥ 1 } be a sequence decreasing to 0. Under appropriate conditions on h_n. We give a functional lnw of the iterated logarithm for the set of increment functions {a_n (l + h_n.) — a_n(l): 0 ≤ / ≤ 1 -h_n}.     

Une Dualité Pour Les Courbes Hyperconvexes

An hyperconvex curve is a curve ξ¹ in such that any n distinct points of the curve are in direct sum. We give here a property of duality of those curves when they admit furthermore an osculating flag. Namely if is a continuous curve of osculating flags of an hyperconvex curve ξ¹, we prove that the curve ξ^n-1 is hyperconvex too and admit a curve of osculating flags.Mathematics Subject Classiffications (2000). 22E40, 53C35     

Un test d'auto-similarité pour les processus gaussiens à accroissements stationnaires

In this Note, we present a method for testing self-similarity of discretized observations of a Gaussian process with stationary increments. The test is based on the estimation of a distance between the process and a set of processes containing all the fractional Brownian motions. This distance is constructed from two estimations of multiscale generalized quadratic variations expectations. The second estimation requires to estimate by regression the self-similarity index H. Both these estimators of H present good robustness and computing time properties compared with maximum likelihood approach, with nearly similar convergence rate.     

Formule de Cauchy-Crofton pour la densité des ensembles sous-analytiques

For the density of subanalytic sets, we give a formula analogous to the classical Cauchy-Crofton formula for the volume. To do this we define the local polar profiles of a subanalytic set and the corresponding finite sequence of local multiplicities which is the real counterpart of the multiplicity of complex analytic sets.     

Algorithmes parallèles asynchrones pour des systèmes singuliers

In this paper we give a convergence result concerning parallel bounded delayed asynchronous algorithms for linear fixed point problems with nonexpansive linear mappings with respect to a weighted maximum norm. This allows us to propose parallel algorithms which converge to the solution of consistent singular systems, including singular M-matrices (see for more details [3]). An important characteristic of our technical framework is that we are able to describe two-stage algorithms.     

Existence et stabilité de roll-waves pour les équations de Saint Venant

Roll-waves are entropic travelling waves of the Saint Venant system with a source term. In this Note, we study two connected problems: on the one hand the existence of roll-waves in a channel with a periodic bottom, on the other hand the linear stability of roll-waves over a flat bottom. The main issue is due to the presence of an infinite number of shocks. With the help of a suitable change of variables, we can restrict our attention to C¹ functions on $\text{R}\text{?{iL,}\text{i∈}\text{Z}\text{}}$. Then we prove the existence of small amplitude roll-waves with wavespeeds oscillating around an average velocity in a channel with a periodic bottom. For channels with a flat bottom, we show the linear stability of roll-waves when the slope is small enough. To cite this article: P. Noble, C. R. Acad. Sci. Paris, Ser. I 338 (2004).     

Un résultat de densité pour les équations de Maxwell

We prove the density of regular fielclx in the space of square-integrahle fields with square-integrable curls and square-integrable tangential traces on the boundary. This space is involved in one of the variational formulations of the electmmagnetism equations.     

Caractéristiques locales et conditions de continuité absolue pour les semi-martingales

Sans résumé     

Théorèmes de dualité pour les corps de fonctions sur des corps locaux supérieurs

Let K be the function field of a smooth projective curve X over a higher-dimensional local field k. We define Tate-Shafarevich groups of a commutative group scheme via cohomology classes locally trivial at each completion of K coming from a closed point of X. We establish duality theorems between Tate-Shafarevich groups for finite groups schemes and for tori.     

Sur la Théorie des Caractéristiques pour les Coniques

Sans résuméAbgedruckt aus den Proceedings der London Mathematical Society, Vol. IX, No. 133, 134. (Sitzung vom 13. Juni 1878.)     

Une identité pour des polynômes d'Appell

In this paper, we establish an identity for some Appell polynomials generalizing explicit formulas for generalized Bernoulli numbers and polynomials.