On the product of self-adjoint operators.
On the range-kernel orthogonality of elementary operators
Let denote the algebra of operators on a complex infinite dimensional Hilbert space . For , the generalized derivation and the elementary operator are defined by and for all . In this paper, we exhibit pairs of operators such that the range-kernel orthogonality of holds for the usual operator norm. We generalize some recent results. We also establish some theorems on the orthogonality of the range and the kernel of with respect to the wider class of unitarily invariant norms on...
On the spectral function of a normal operator
On the spectrum of singularly perturbed operators
On Unitary Operators Inducing Measure-Preserving Transformations.
On weak supercyclicity II
This paper considers weak supercyclicity for bounded linear operators on a normed space. On the one hand, weak supercyclicity is investigated for classes of Hilbert-space operators: (i) self-adjoint operators are not weakly supercyclic, (ii) diagonalizable operators are not weakly -sequentially supercyclic, and (iii) weak -sequential supercyclicity is preserved between a unitary operator and its adjoint. On the other hand, weak supercyclicity is investigated for classes of normed-space operators:...
Once more about the monotonicity of the Temple quotients
A new proof of the monotonicity of the Temple quotients for the computation of the dominant eigenvalue of a bounded linear normal operator in a Hilbert space is given. Another goal of the paper is a precise analysis of the length of the interval for admissible shifts for the Temple quotients.
One-dimensional graph perturbations of selfadjoint relations.
Operator means, fixed points, and the norm convergence of monotone approximants.
Operator norm inequalities of Minkowski type.
Operators with thin spectral sets.
Polar decomposition approach to Reid's inequality.
Polar decomposition under perturbations of the scalar product.
Polinomios ortogonales asociados con problemas espectrales
Positive operator bimeasures and a noncommutative generalization
For C*-algebras A and B and a Hilbert space H, a class of bilinear maps Φ: A× B → L(H), analogous to completely positive linear maps, is studied. A Stinespring type representation theorem is proved, and in case A and B are commutative, the class is shown to coincide with that of positive bilinear maps. As an application, the extendibility of a positive operator bimeasure to a positive operator measure is shown to be equivalent to various conditions involving positive scalar bimeasures, pairs of...
Positivity Improving Operators and Hypercontractivity.
Positivity of operator-matrices of Hua-type.
Powers and commutativity of selfadjoint operators.
Problème des moments matriciels sur la droite : construction d'une famille de solutions et questions d'unicité
Product of operators and numerical range preserving maps
Let V be the C*-algebra B(H) of bounded linear operators acting on the Hilbert space H, or the Jordan algebra S(H) of self-adjoint operators in B(H). For a fixed sequence (i₁, ..., iₘ) with i₁, ..., iₘ ∈ 1, ..., k, define a product of by . This includes the usual product and the Jordan triple product A*B = ABA as special cases. Denote the numerical range of A ∈ V by W(A) = (Ax,x): x ∈ H, (x,x) = 1. If there is a unitary operator U and a scalar μ satisfying such that ϕ: V → V has the form A...