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3-5 avril 2017
Université d'Orléans, Mathématiques
Europe/Paris timezone
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Affichage13 contributions sur 13
Let $d\ge  2$, $\Omega\subset R^d$ be a smooth bounded domain and $f\in L^d(\Omega)$ with $\int_R f(x)dx=0$. Bourgain and Brezis proved that there exists a vector field $X \in W^{1;d}(\Omega)\cap L^\infty(\Omega)$ such that $div X = f$ and $||f||_{W^{1;d}}+||f||_{L^\infty}\le C ||f||_{L^d}. $ We will discuss various extensions of this result to more general functions spaces, and present some r ... Plus
Présenté par Mr. Emmanuel RUSS on 4 avr. 2017 à 10:45
The smoothness of a function $f$ is described by the rate of convergence of the smoothings of $f$ to $f$. Another way to measure smoothness is given by the decay properties of the derivatives of these smoothings: this is encoded by the theory of weighted Sobolev spaces, developed in the 60s. In the first part of the lecture, we will recall some striking results of this theory, with focus on Sob ... Plus
Présenté par Mr. Petru MIRONESCU on 3 avr. 2017 à 15:15
Affine measures have been introduced in the past to facilitate the study of Fourier Restriction and the related question of the L^p smoothing properties of averages along submanifolds (convolution Radon transforms). They capture in a geometric way the role of curvature. In this talk we present the Affine Measures and then discuss the geometric interpretation of these objects - a line of research t ... Plus
Présenté par Dr. Marco VITTURI on 4 avr. 2017 à 16:30
We study the asymptotic behaviour of the powers $T^n$ of a continuous composition operator $T$ on an arbitrary Banach space $X$ of holomorphic functions on the open unit disc of the complex plane. We show that for composition operators, one has the following dichotomy: either the powers converge uniformly or they do not converge even strongly. We also show that uniform convergence of the powers ... Plus
Présenté par Prof. Isabelle CHALENDAR on 5 avr. 2017 à 11:45
Présenté par Ms. Cristina BENEA on 3 avr. 2017 à 16:30
Présenté par Ms. Dorothee FREY on 4 avr. 2017 à 15:15
Lecture 1: An important theorem in harmonic analysis connects the commutator of multiplication by a function and Calderon-Zygmund operators and the functions of bounded mean oscillation. And as a dual statement, it connects the Hardy space with a certain ``factorization'' of Lebesgue spaces. During these lectures we will give proofs of these theorems using tools from dyadic harmonic analys ... Plus
Présenté par Mr. Brett WICK on 3 avr. 2017 à 14:00
Lecture 2 . .
Présenté par Mr. Brett WICK on 4 avr. 2017 à 09:15
Lecture 3
Présenté par Mr. Brett WICK on 5 avr. 2017 à 09:15
Let $G$ be a locally compact group, and let $1\le p < \infty$. Consider the weighted $L^p$-space $L^p(G,\omega)=\{f:\int|f\omega|^p<\infty\}$, where $\omega:G\to \R$ is a positive measurable function. Under appropriate conditions on $\omega$, $G$ acts on $L^p(G,\omega)$ by translations. When is this action hypercyclic, that is, there is a function in this space such that the set of all its transla ... Plus
Présenté par Dr. Yulia KUZNETSOVA on 3 avr. 2017 à 17:30
Nous étudions les ensembles d’interpolation, d’unicité et d’échantillonnage multiple pour les espaces de Fock classiques dans le cas où la multiplicité est non bornée. Nous montrons, dans le cas hilbertien ainsi que celui de la norme uniforme, qu’il n’y a pas de suites simultanément d’échantillonnage et d’interpolation lorsque la multiplicité tend vers l’infini. Ceci ... Plus
Présenté par Mr. Karim KELLAY on 5 avr. 2017 à 10:45
In a recent paper Alaifari, Pierce & S. Steinerberger conjectured a lower bound for the Hilbert transform $H$ of the form $$ ||Hf||_{L^2(J)}\geq \exp(-c_{I,J}||f'||_1/||f||_2) ||f||_{L^2(I)} $$ when $I,J$ are disjoint intervals and $f\in L^2,f'\in L^1$. The aim of this talk is to present the motivation of this conjecture as an invitation to study lower bounds for Calderon Zygmund operators. We ... Plus
Présenté par Philippe JAMING on 4 avr. 2017 à 11:45
In 1978, D. Békollé and A. Bonami characterized the exact range of weights for which the Bergman projection is bounded on weighted Lebesgue spaces. In 2013, S. Pott and M. C. Reguera found the exact dependence of the norm of the Bergman projection on the Békollé-Bonami characteristic of the weight. In this talk, we discuss extension of these results to the upper-triangle case.
Présenté par Dr. Benoit Florent SEHBA on 4 avr. 2017 à 14:15