Results 31 to 40 of about 499 (74)
Decomposing numerical ranges along with spectral sets
, 2009 This note is to indicate the new sphere of applicability of the method developed by Mlak as well as by the author.
Szafraniec, F. H.
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Generalized Derivations and Norm Equality in Normed Ideals [PDF]
, 2011 2000 Mathematics Subject Classification: 47A10, 47A12, 47A30, 47B10, 47B20, 47B37, 47B47, 47D50.We compare the norm of a generalized derivation on a Hilbert space with the norm of its restrictions to Schatten norm ...
Barraa, Mohamed
core
Numerical radius inequalities associated with the Cartesian decomposition
, 2015 We give several sharp numerical radius inequalities associated with the Cartesian decomposition of a Hilbert space operator A = B + iC . Among other inequalities, it is shown that 1 2 ‖ |B| + |C|‖ wr(A) ‖ |B| + |C|‖ for 0 < r 2 , where w(·) and ...
F. Kittaneh
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Scalar approximants of quadratic operators with applications
, 2018 Among other results, we find the best scalar approximant of a quadratic operator with respect to the numerical radius and the operator norm. We use these results to give estimates for the numerical radii of products and commutators of quadratic operators.
A. Abu-Omar, P. Wu
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Private quantum codes: introduction and connection with higher rank numerical ranges
, 2013 We give a brief introduction to private quantum codes, a basic notion in quantum cryptography and key distribution. Private code states are characterized by indistinguishability of their output states under the action of a quantum channel, and we show ...
Kribs, D. W., Plosker, S.
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A note on the $C$-numerical radius and the $\lambda$-Aluthge transform in finite factors
, 2017 We prove that for any two elements $A$, $B$ in a factor $M$, if $B$ commutes with all the unitary conjugates of $A$, then either $A$ or $B$ is in $\mathbb{C}I$.
Fang, Junsheng +2 more
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A fiedler-type theorem for the determinant of J-positive matrices
, 2016 In this note we characterize the set of all possible values attained by the determinant of the sum of two J -positive matrices with prescribed spectra, under a natural compatibility condition. Mathematics subject classification (2010): 46C20, 47A12.
N. Bebiano, J. Providência
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On the block numerical range of operators on arbitrary Banach spaces
, 2018 We investigate the block numerical range of bounded linear operators on arbitrary Banach spaces. We show that the spectrum of an operator is always contained in the closure of its block numerical range.
Agnes Radl, M. Wolff
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Domaine Numérique du produit AB avec A normal [PDF]
, 2006 2000 Mathematics Subject Classification: 18B30, 47A12.Let A, B be two linear operators on a complex Hilbert space H. We extend a Bouldin's result (1969) conserning W(AB) - the numerical range of the product AB. We show, when AB = BA and A is normal, than
Kaadoud, Mohamed Chraïbi
core
ON THE MAXIMAL NUMERICAL RANGE OF ELEMENTARY OPERATORS
, 2017 The notion of the numerical range has been generalized in different directions. One such direction, is the maximal numerical range introduced by Stampfli (1970) to derive an identity for the norm of a derivation on L(H). Unlike the other generalizations,
Mati Runji +2 more
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