Time regularity and functions of the Volterra operator
Our aim is to prove that for any fixed 1/2 < α < 1 there exists a Hilbert space contraction T such that σ(T) = 1 and . This answers Zemánek’s question on the time regularity property.
Transformation de Poisson sur un arbre localement fini
Dans cet article on étudie en premier lieu la résolvante (le noyau de Green) d’un opérateur agissant sur un arbre localement fini. Ce noyau est supposé invariant par un groupe d’automorphismes de l’arbre. On donne l’expression générique de cette résolvante et on établit des simplifications sous différentes hypothèses sur .En second lieu on introduit la transformation de Poisson qui associe à une mesure additive finie sur l’espace des bouts de l’arbre une fonction propre de l’ opérateur. On...
Transition operators on co-compact G-spaces.
We develop methods for studying transition operators on metric spaces that are invariant under a co-compact group which acts properly. A basic requirement is a decomposition of such operators with respect to the group orbits. We then introduce reduced transition operators on the compact factor space whose norms and spectral radii are upper bounds for the Lp-norms and spectral radii of the original operator. If the group is amenable then the spectral radii of the original and reduced operators coincide,...
Two endpoint bounds for generalized Radon transforms in the plane.
Two-dimensional real symmetric spaces with maximal projection constant
Let V be a two-dimensional real symmetric space with unit ball having 8n extreme points. Let λ(V) denote the absolute projection constant of V. We show that where is the space whose ball is a regular 8n-polygon. Also we reprove a result of [1] and [5] which states that for any two-dimensional real symmetric space V.
Uncertainty principles revisited.
Uniformly convex operators and martingale type.
The concept of uniform convexity of a Banach space was gen- eralized to linear operators between Banach spaces and studied by Beauzamy [1]. Under this generalization, a Banach space X is uniformly convex if and only if its identity map Ix is. Pisier showe
Upper bounds for the Euclidean operator radius and applications.
Variations on Yano's extrapolation theorem.
We give very short and transparent proofs of extrapolation theorems of Yano type in the framework of Lorentz spaces. The decomposition technique developed in Edmunds-Krbec (2000) enables us to obtain known and new results in a unified manner.
Weighted inequalities for the Hilbert transform and the adjoint operator in the continuous case
Weighted Lorentz norm inequalities for integral operators
Weighted Morrey-Herz spaces and applications.
Weighted norm inequalities for the Hardy-Little-wood maximal function for one parameter rectangles
Weyl's theorem for algebraically absolute--paranormal operators.
Young's (in)equality for compact operators
If a,b are n × n matrices, T. Ando proved that Young’s inequality is valid for their singular values: if p > 1 and 1/p + 1/q = 1, then for all k. Later, this result was extended to the singular values of a pair of compact operators acting on a Hilbert space by J. Erlijman, D. R. Farenick and R. Zeng. In this paper we prove that if a,b are compact operators, then equality holds in Young’s inequality if and only if .
Zur besten normalen Approximation komplexer Matrizen in der Euklidischen Norm.
Неравенства бернштейновского типа в абстрактном гармоническом анализе
Нормы связанных состояний
О замкнутых эрмитовых операторах и их самосопряженных расширениях
О кратной полноте собственных и присоединенных векторов операторного пучка в пространстве с двумя нормами