Ultraproducts in Banach space theory.
Ultraproducts of -predual spaces
Ultraproduits d'espaces de Banach
Ultraproduits d’espaces et d’espaces d’Orlicz
Ultrasymmetric sequence spaces in approximation theory.
Let φ(t) be a positive increasing function and let Ê be an arbitrary sequence space, rearrangement-invariant with respect to the atomic measure µ(n) = 1/n. Let {an*} mean the decreasing rearrangement of a sequence {|an|}. A sequence space lφ,E with symmetric (quasi)norm || {φ(n)an*} ||Ê is called ultrasymmetric, because it is not only intermediate but also interpolation between the corresponding Lorentz and Marcinkiewicz spaces Λφ and Mφ. We study properties of the spaces lφ,E for all admissible...
Un altro modo di costruire la serie di Fourier delle distribuzioni di una variabile quasi periodiche
Un espace de Banach réticulé qui a presque la propriété de Radon-Nikodym
Un espace jouissant de la propriété de Schur et de la propriété de Radon-Nikodym
Un espace non Radon-Nikodým sans arbre diadique
Un lemme de H. P. Rosenthal
Un théorème d’extrapolation et son application aux suites sommables dans
Una caracterización de los operadores de Fredholm y semi-Fredholm.
Una nota sobre los espacios de Sobolev.
Una nota sobre los espacios de Sobolev anisótropos vectoriales LΓp (E)*.
Una nota sobre los subespacios K-complementados de los espacios escalonados de sucesiones.
Una propiedad de los espacios de Banach que no son casirreflexivos.
Unbounded symmetric homogeneous domains in spaces of operators
Uncomplementability of spaces of compact operators in larger spaces of operators
In the first part of the paper we prove some new result improving all those already known about the equivalence of the nonexistence of a projection (of any norm) onto the space of compact operators and the containment of in the same space of compact operators. Then we show several results implying that the space of compact operators is uncomplemented by norm one projections in larger spaces of operators. The paper ends with a list of questions naturally rising from old results and the results...
Uncomplemented copies of C(K) inside C(K).
Throughout this note, whenever K is a compact space C(K) denotes the Banach space of continuous functions on K endowed with the sup norm. Though it is well known that every infinite dimensional Banach space contains uncomplemented subspaces, things may be different when only C(K) spaces are considered. For instance, every copy of l∞ = C(BN) is complemented wherever it is found. In [5] Pelzcynski found: Theorem 1. Let K be a compact metric space. If a separable Banach space X contains a subspace...
Unconditional and normalised bases