On a problem of Kadison and Singer.
On a weighted Toeplitz operator and its commutant.
On an infinite-dimensional version of the Kreiss matrix theorem
On bases and the shift operator
On Bernstein type rational functions of two variables
On convexity of composition and multiplication operators on weighted Hardy spaces.
On cyclicity in weighted Dirichlet spaces.
On extended eigenvalues and extended eigenvectors of truncated shift
In this paper we consider the truncated shift operator Su on the model space K2u := H2 θ uH2. We say that a complex number λ is an extended eigenvalue of Su if there exists a nonzero operator X, called extended eigenvector associated to λ, and satisfying the equation SuX = λXSu. We give a complete description of the set of extended eigenvectors of Su, in the case of u is a Blaschke product..
On matrix transformations concerning the Nakano vector-valued sequence space.
On norm closed ideals in
It is well known that the only proper non-trivial norm closed ideal in the algebra L(X) for (1 ≤ p < ∞) or X = c₀ is the ideal of compact operators. The next natural question is to describe all closed ideals of for 1 ≤ p,q < ∞, p ≠ q, or equivalently, the closed ideals in for p < q. This paper shows that for 1 < p < 2 < q < ∞ there are at least four distinct proper closed ideals in , including one that has not been studied before. The proofs use various methods from Banach...
On some BK spaces.
On the Banach-Stone problem
Let X and Y be locally compact Hausdorff spaces, let E and F be Banach spaces, and let T be a linear isometry from C₀(X,E) into C₀(Y,F). We provide three new answers to the Banach-Stone problem: (1) T can always be written as a generalized weighted composition operator if and only if F is strictly convex; (2) if T is onto then T can be written as a weighted composition operator in a weak sense; and (3) if T is onto and F does not contain a copy of then T can be written as a weighted composition...
On the -characteristic of fractional powers of linear operators
We describe the geometric structure of the -characteristic of fractional powers of bounded or compact linear operators over domains with arbitrary measure. The description builds essentially on the Riesz-Thorin and Marcinkiewicz-Stein-Weiss- Ovchinnikov interpolation theorems, as well as on the Krasnosel’skij-Krejn factorization theorem.
On the diagonal of matrix transformations
On the fine spectra of some averaging operators.
On the fine spectrum of generalized upper double-band matrices over the sequence space
On the local spectral properties of weighted shift operators
We study the local spectral properties of both unilateral and bilateral weighted shift operators.
On the reflexivity of multigenerator algebras [Book]
On the shift operators.
On the space of φ-nuclear operators on l2.
We consider the generalization Sphi of the Schatten classes Sp obtained in correspondence with opportune continuous, strictly increasing, sub-additive functions phi such that phi(0) = 0 and phi(1) = 1. The purpose of this note is to study the spaces Sphi of the phi-nuclear operators and to compare their properties to those of the by now well-known space S1 of nuclear operators.