On operator-valued analytic functions with positive real part whose logarithm belongs to a class
On Optimal Spectral Estimator for Multi-Dimensional Time Series with an Infinite Number of Sample Points.
On order structure and operators in L ∞(μ)
It is known that there is a continuous linear functional on L ∞ which is not narrow. On the other hand, every order-to-norm continuous AM-compact operator from L ∞(μ) to a Banach space is narrow. We study order-to-norm continuous operators acting from L ∞(μ) with a finite atomless measure μ to a Banach space. One of our main results asserts that every order-to-norm continuous operator from L ∞(μ) to c 0(Γ) is narrow while not every such an operator is AM-compact.
On p-absolutely summing operators acting on Banach lattices
On partial isometries in C*-algebras
We study similarity to partial isometries in C*-algebras as well as their relationship with generalized inverses. Most of the results extend some recent results regarding partial isometries on Hilbert spaces. Moreover, we describe partial isometries by means of interpolation polynomials.
On peripheral eigenvalues and eigenvectors of certain regular operators. (Über periphere Eigenwerte und Eigenvektoren bei gewissen regulären Operatoren.)
On Perturbations of Linear m-Accetive Operators on Reflexive Banach Spaces.
On powers of -hyponormal and log-hyponormal operators.
On precompact multiplication operators on weighted function spaces.
On product of projections
An operator with infinite dimensional kernel is positive iff it is a positive scalar times a certain product of three projections.
On products of non-commuting sectorial operators
On products of some Toeplitz operators on polyanalytic Fock spaces
The purpose of this paper is to study the Sarason’s problem on Fock spaces of polyanalytic functions. Namely, given two polyanalytic symbols and , we establish a necessary and sufficient condition for the boundedness of some Toeplitz products subjected to certain restriction on and . We also characterize this property in terms of the Berezin transform.
On proper boundary points of the spectrum and complemented eigenspaces.
On Pták’s generalization of Hankel operators
In 1997 Pták defined generalized Hankel operators as follows: Given two contractions and , an operator is said to be a generalized Hankel operator if and satisfies a boundedness condition that depends on the unitary parts of the minimal isometric dilations of and . This approach, call it (P), contrasts with a previous one developed by Pták and Vrbová in 1988, call it (PV), based on the existence of a previously defined generalized Toeplitz operator. There seemed to be a strong but somewhat...
On quasi-analytic vectors for some classes of operators
On quasi-compactness of operator nets on Banach spaces
The paper introduces a notion of quasi-compact operator net on a Banach space. It is proved that quasi-compactness of a uniform Lotz-Räbiger net is equivalent to quasi-compactness of some operator . We prove that strong convergence of a quasi-compact uniform Lotz-Räbiger net implies uniform convergence to a finite-rank projection. Precompactness of operator nets is also investigated.
On quasi-free Hilbert modules.
On quasinormal operators
On Quasi-Normality of Two-Sided Multiplication
2000 Mathematics Subject Classification: 47B47, 47B10, 47A30.In this note, we characterize quasi-normality of two-sided multiplication, restricted to a norm ideal and we extend this result, to an important class which contains all quasi-normal operators. Also we give some applications of this result.
On reiteration and the behaviour of weak compactness under certain interpolation methods.
This article deals with K- and J-spaces defined by means of polygons. First we establish some reiteration formulae involving the real method, and then we study the behaviour of weakly compact operators. We also show optimality of the weak compactness results.