Une introduction aux opérateurs de Toeplitz
Une nouvelle caractérisation des applications -sommantes
Une nouvelle classe d'espaces de Banach vérifiant le théorème de Grothendieck
Soit un espace et soit un sous-espace réflexif de dimension infinie de . Nous montrons que le quotient vérifie le théorème de Grothendieck, c’est-à-dire que tout opérateur de dans un espace de Hilbert est 1-sommant; par ailleurs, n’est pas un espace . Cela permet de répondre négativement à une question de Lindenstrauss-Pełczyński ainsi qu’à une question similaire de Grothendieck.
Une nouvelle démonstration d'un théorème de Grothendieck
Une remarque sur un théorème de Bourgain
Unicellularity of the multiplication operator on Banach spaces of formal power series
Let be a sequence of positive numbers and 1 ≤ p < ∞. We consider the space of all power series such that . We give some sufficient conditions for the multiplication operator, , to be unicellular on the Banach space . This generalizes the main results obtained by Lu Fang [1].
Uniform bounds for the bilinear Hilbert transforms (II).
We continue the investigation initiated in [Grafakos, L. and Li, X.: Uniform bounds for the bilinear Hilbert transforms (I). Ann. of Math. (2)159 (2004), 889-933] of uniform Lp bounds for the family of bilinear Hilbert transformsHα,β(f,g)(x) = p.v. ∫R f(x - αt) g (x - βt) dt/t.
Uniform Convergence of Operators and Grothendieck Spaces with the Dunford-Pettis Property.
Uniform Convergence of Operators on L... and Similar Spaces.
Uniform Ergodic Theormes for Markov Operators on C(X).
Uniform estimates for some paraproducts.
Uniform ordered spectral decompositions
Uniformly bounded composition operators in the banach space of bounded (p, k)-variation in the sense of Riesz-Popoviciu
We prove that if the composition operator F generated by a function f: [a, b] × ℝ → ℝ maps the space of bounded (p, k)-variation in the sense of Riesz-Popoviciu, p ≥ 1, k an integer, denoted by RV(p,k)[a, b], into itself and is uniformly bounded then RV(p,k)[a, b] satisfies the Matkowski condition.
Uniformly Continuous Set-Valued Composition Operators in the Spaces of Functions of Bounded Variation in the Sense of Riesz
We show that any uniformly continuous and convex compact valued Nemytskiĭ composition operator acting in the spaces of functions of bounded φ-variation in the sense of Riesz is generated by an affine function.
Uniformly convergent adaptive methods for a class of parametric operator equations∗
We derive and analyze adaptive solvers for boundary value problems in which the differential operator depends affinely on a sequence of parameters. These methods converge uniformly in the parameters and provide an upper bound for the maximal error. Numerical computations indicate that they are more efficient than similar methods that control the error in a mean square sense.
Uniformly convergent adaptive methods for a class of parametric operator equations∗
We derive and analyze adaptive solvers for boundary value problems in which the differential operator depends affinely on a sequence of parameters. These methods converge uniformly in the parameters and provide an upper bound for the maximal error. Numerical computations indicate that they are more efficient than similar methods that control the error in a mean square sense.
Uniformly ergodic A-contractions on Hilbert spaces
We study the concept of uniform (quasi-) A-ergodicity for A-contractions on a Hilbert space, where A is a positive operator. More precisely, we investigate the role of closedness of certain ranges in the uniformly ergodic behavior of A-contractions. We use some known results of M. Lin, M. Mbekhta and J. Zemánek, and S. Grabiner and J. Zemánek, concerning the uniform convergence of the Cesàro means of an operator, to obtain similar versions for A-contractions. Thus, we continue the study of A-ergodic...
Uniformly summing sets of operators on spaces of continuous functions.
Unimodular Eigenvalues and Invariant Measures for Linear Operators.
Uniqueness condition for the Pick problem.