Remarks on invariant subspaces and Lp-solutions of the Schrödinger evolution equation.
The aim of this paper is to derive some relationships between the concepts of the property of strong 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.
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.
Dans ce travail on s’intéresse aux opérateurs de composition sur certains espaces de Besov et de Lizorkin-Triebel à valeurs dans . Dans le but de caractériser les fonctions qui opèrent, on établit que la condition de Lipschitz, locale ou globale suivant que l’espace ou se plonge ou non dans , est nécessaire pour , et que l’appartenance locale au même espace l’est aussi pour . Nous étudions enfin la régularité de l’opérateur .
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.
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.