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Remarks on some properties in the geometric theory of Banach spaces

Wagdy Gomaa El-Sayed, Krzysztof Fraczek (1996)

Commentationes Mathematicae Universitatis Carolinae

The aim of this paper is to derive some relationships between the concepts of the property of strong ( α ' ) introduced recently by Hong-Kun Xu and the so-called characteristic of near convexity defined by Goebel and Sȩkowski. Particularly we provide very simple proof of a result obtained by Hong-Kun Xu.

Remarks on the Istratescu measure of noncompactness.

Janusz Dronka (1993)

Collectanea Mathematica

In this paper we give estimations of Istratescu measure of noncompactness I(X) of a set X C lp(E1,...,En) in terms of measures I(Xj) (j=1,...,n) of projections Xj of X on Ej. Also a converse problem of finding a set X for which the measure I(X) satisfies the estimations under consideration is considered.

Remarques sur le calcul symbolique dans certains espaces de Besov à valeurs vectorielles

Salah Eddine Allaoui (2009)

Annales mathématiques Blaise Pascal

Dans ce travail on s’intéresse aux opérateurs de composition T f ( g ) : = f g sur certains espaces de Besov et de Lizorkin-Triebel à valeurs dans m . Dans le but de caractériser les fonctions qui opèrent, on établit que la condition de Lipschitz, locale ou globale suivant que l’espace B p , q s ( n , m ) ou F p , q s ( n , m ) se plonge ou non dans L ( n , m ) , est nécessaire pour s > 0 , et que l’appartenance locale au même espace l’est aussi pour m n . Nous étudions enfin la régularité de l’opérateur T f .

Renormings of c 0 and the minimal displacement problem

Łukasz Piasecki (2015)

Annales UMCS, Mathematica

The aim of this paper is to show that for every Banach space (X, || · ||) containing asymptotically isometric copy of the space c0 there is a bounded, closed and convex set C ⊂ X with the Chebyshev radius r(C) = 1 such that for every k ≥ 1 there exists a k-contractive mapping T : C → C with [...] for any x ∊ C.

Representation of multilinear operators on C(K, X) spaces.

Ignacio Villanueva (2002)

RACSAM

We present a Riesz type representation theorem for multilinear operators defined on the product of C(K,X) spaces with values in a Banach space. In order to do this we make a brief exposition of the theory of operator valued polymeasures.

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