The forward estimation problem for stationary and ergodic time series {X n } ∞ n=0 taking values from a finite alphabet X is to estimate the probability that X n+1 = x based on the observations X i , 0 ≤ i ≤ n without prior knowledge of the distribution of the process {X n }. We present a simple procedure g n which is evaluated on the data)| → 0 almost surely for a subclass of all stationary an...

Limiting laws, as t →∞, for Brownian motion penalised by the longest length of excursions up to t , or up to the last zero before t , or again, up to the first zero after t , are shown to exist, and are characterized. Résumé. Il est prouvé que les lois limites, lorsque t → ∞, du mouvement brownien pénalisé par la plus grande longueur des excursions jusqu’en t , ou bien jusqu’au dernier zéro ava...

We show that the so-called low-regret (or least-regret) control by J. L. Lions [8] fits on the control of ill-posed problems. At each time, we give the characterization of the so-called no-regret control by means of singular optimality systems. For the backward heat ill-posed problem, no Slater hypothesis is assumed on the admissible set of controls Uad. This work is two pieces, and two methods...

Résumé – Dans cet article, nous proposons un codage spatio-temporel en bloc non orthogonal de rendement symbole 1 pour 3 antennes à l’émission. Ce code permet d’améliorer les performances d’un système de communications sans fil. Le code proposé peut être décodé soit simplement par forçage à zéro soit en utilisant un décodeur à maximum de vraisemblance à complexité réduite. Finalement, nous avon...

We show that any closed spin manifold not diffeomorphic to the two-sphere admits a sequence of volume-one-Riemannian metrics for which the smallest non-zero Dirac eigenvalue tends to zero. As an application, we compare the Dirac spectrum with the conformal volume. Spineurs presque harmoniques Résumé. Nous montrons que, sur toute variété spinorielle compacte sans bord non difféomorphe à la sphèr...