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Mostrando ítems 1-10 de 21
Artículo
Quasi-similarity of contractions having 2 x 2 a singular characteristic function
(Elsevier, 2008)
LetT1:H1→H1be a completely non-unitary contraction having a 2×2 singular characteristic function Θ1; thatis, Θ1=[θi,j]i, j=1,2withθij∈H∞and det(Θ1)=0. Asit is well known, Θ1is a singular matrix if and only ifΘ1can be written ...
Artículo
Volterra operators and semigroups in weighted Banach spaces of analytic functions
(Springer Open Choice, 2014)
We characterize the boundedness, compactness and weak compactness of Volterra operators Vg( f )(z) := z 0 f (ζ )g (ζ ) dζ acting between different weighted spaces of type H∞ v in terms of the symbol function g, ...
Artículo
Complemented copies of c0 in vector-valued Köthe-Dieudonné function spaces
(Springer, 1992)
Let [Lambda] be a barrelled perfect (in the sense of J. Dieudonné) Köthe space of measurable functions defined on an atomless finite Radon measure space. Let X be a Banach space containing a copy of c0, then the space ...
Artículo
On Pták's generalization of Hankel operators
(Springer, 2001)
In 1997 Pták defined generalized Hankel operators as follows: Given two contractions T1 ∈ B(H1) and T2 ∈ B(H2), an operator X: H1 → H2 is said to be a generalized Hankel operator if T2X = XT ∗ 1 and X satisfies a ...
Artículo
A note on the Köthe dual of Banach-valued echelon spaces
(Universitat de Barcelona. Promociones y Publicaciones Universitarias, PPU, 1988)
Several different ways of defining the Köthe dual of echelon spaces of Banach-valued functions are shown to be equivalent
Artículo
in λ-sums of normed spaces
(Guy Hirsch, 1989)
Let E n , n=1,2,··. be a sequence of normed spaces and λ an AK-Köthe sequence space. The λ-sum of the spaces E n is defined by λ{E n }:={(x n ) n : x n is in E n and (|x n |) n ∈λ}. Starting from the topology in λ, λ{E n ...
Artículo
Lifting the solutions of a Toeplitz type equation; the semigroup case X = TsXT*s
(Universita del Salento, 1995)
A Toeplitz operator with respect to a contractive representation {Ts} of an abelian semigroup Σ in a Hilbert space H is an operator X ∈ B(H) such that X = TsXT ∗ s for all s ∈ Σ. We show that if {Ts} has a minimal ...
Artículo
Completeness of spaces wth Toeplitz decompositions
(Real Academia de Ciencias Exactas, Físicas y Naturales, 1998)
Artículo
The space of countably simple bounded functions with values in a DF-space
(Universidad Complutense de Madrid, 1994)
We study the possibility of lifting some properties, as being a (barreled, quasi-barreled, bornological, or ultrabornological) DF, gDF, or quasi-normable space, from a locally convex space E to the space S ,\ 0(m,E) , ...
Artículo
The space of Pettis integrable functions is barrelled
(American Mathematical Society, 1992)
It is well known that the normed space of Pettis integrable functions from a finite measure space to a Banach space is not complete in general. Here we prove that this space is always barrelled; this tells us that we may ...