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Non-Linear Traces on Matrix Algebras, Majorization, Unitarily Invariant Norms and 2-Positivity
We study non-linear traces of Choquet type and Sugeno type on matrix algebras. They have certain partial additivities. We show that these partial...
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A Characterization of Unitary-Antiunitary Similarity Transformations via Kubo–Ando Means
In this note, we characterize all those bijective transformations on the set of positive semidefinite matrices which preserve an arbitrary unitarily...
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Maps Preserving Schatten Norms of Power Means of Positive Operators
In this paper, we determine the general form of transformations on positive operators preserving a p -norm of a power mean with positive exponent. The...
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Estimations of the Operator Resolvent by Higher Order Cesàro Means
Some growth conditions of the resolvent function of a Banach space operator are investigated using higher order Cesàro means. More precisely, Abel...
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On Ergodic Operator Means in Banach Spaces
We consider a large class of operator means and prove that a number of ergodic theorems, as well as growth estimates known for particular cases,...
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Roots in Operator and Banach Algebras
We show that several known facts concerning roots of matrices generalize to operator algebras and Banach algebras. We show for example that the...
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Transformations Preserving Norms of Means of Positive Operators and Nonnegative Functions
Motivated by recent investigations on norm-additive and spectrally multiplicative maps on various spaces of functions, in this paper we determine all...
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Q-functions and Boundary Triplets of Nonnegative Operators
Operator-valued Q-functions for special pairs of nonnegative selfadjoint extensions of nonnegative not necessarily densely defined operators are...
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On Means of Nonnegative Sesquilinear Forms
The aim of this paper is to generalize the theory of operator connections for nonnegative sesquilinear forms. As an application, we investigate the...
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Q-functions of Hermitian Contractions of Krein-Ovcharenko Type
In this paper operator-valued Q -functions of Krein-Ovcharenko type are introduced. Such functions arise from the extension theory of Hermitian...
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Geodesics for Dual Connections and Means on Symmetric Cones
Means on self-dual and homogeneous cones (, i.e., symmetric cones) are discussed from a viewpoint of differential geometry with affine connections....
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Q-functions of Quasi-selfadjoint Contractions
A bounded everywhere defined operator T in a Hilbert space ℌ is said to be a quasi-selfadjoint contraction or (for short) a qsc-operator, if T is a...