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On completely bounded bimodule maps over W*-algebras

Bojan Magajna (2003)

Studia Mathematica

It is proved that for a von Neumann algebra A ⊆ B(ℋ ) the subspace of normal maps is dense in the space of all completely bounded A-bimodule homomorphisms of B(ℋ ) in the point norm topology if and only if the same holds for the corresponding unit balls, which is the case if and only if A is atomic with no central summands of type I , . Then a duality result for normal operator modules is presented and applied to the following problem. Given an operator space X and a von Neumann algebra A, is the map...

On complex interpolation and spectral continuity

Karen Saxe (1998)

Studia Mathematica

Let [ X 0 , X 1 ] t , 0 ≤ t ≤ 1, be Banach spaces obtained via complex interpolation. With suitable hypotheses, linear operators T that act boundedly on both X 0 and X 1 will act boundedly on each [ X 0 , X 1 ] t . Let T t denote such an operator when considered on [ X 0 , X 1 ] t , and σ ( T t ) denote its spectrum. We are motivated by the question of whether or not the map t σ ( T t ) is continuous on (0,1); this question remains open. In this paper, we study continuity of two related maps: t ( σ ( T t ) ) (polynomially convex hull) and t e ( σ ( T t ) ) (boundary of the polynomially convex...

On concentrated probabilities

Wojciech Bartoszek (1995)

Annales Polonici Mathematici

Let G be a locally compact Polish group with an invariant metric. We provide sufficient and necessary conditions for the existence of a compact set A ⊆ G and a sequence g n G such that μ n ( g n A ) 1 for all n. It is noticed that such measures μ form a meager subset of all probabilities on G in the weak measure topology. If for some k the convolution power μ k has nontrivial absolutely continuous component then a similar characterization is obtained for any locally compact, σ-compact, unimodular, Hausdorff topological...

On condensing discrete dynamical systems

Valter Šeda (2000)

Mathematica Bohemica

In the paper the fundamental properties of discrete dynamical systems generated by an α -condensing mapping ( α is the Kuratowski measure of noncompactness) are studied. The results extend and deepen those obtained by M. A. Krasnosel’skij and A. V. Lusnikov in [21]. They are also applied to study a mathematical model for spreading of an infectious disease investigated by P. Takac in [35], [36].

On Connection between Characterestic Functions and the Caratheodori Class Functions

Zolotarev, Vladimir A., Hatamleh, Raéd (2006)

Serdica Mathematical Journal

2000 Mathematics Subject Classification: 47A65, 45S78.Connection of characteristic functions S(z) of nonunitary operator T with the functions of Caratheodori class is established. It was demonstrated that the representing measures from integral representation of the function of Caratheodori's class are defined by restrictions of spectral measures of unitary dilation, of a restricted operator T on the corresponding defect subspaces.

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