Results 11 to 20 of about 456,012 (313)

The Numerical Range of 6 Χ 6 Irreducible Matrices [PDF]

Al-Rafidain Journal of Computer Sciences and Mathematics, 2007
In this paper, we consider the problem of characterizing the numerical range of 6 by 6 irreducible matrices which have line segments on their boundary.
Ahmed Sabir
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The numerical range and the essential numerical range [PDF]

Proceedings of the American Mathematical Society, 1977
A simple proof is given of Lancaster’s theorem that the convex hull of the numerical and essential numerical ranges of a Hilbert space operator is the closure of the numerical range.
openaire   +2 more sources

Joint numerical ranges: recent advances and applications minicourse by V. Müller and Yu. Tomilov

Concrete Operators, 2020
We present a survey of some recent results concerning joint numerical ranges of n-tuples of Hilbert space operators, accompanied with several new observations and remarks.
Müller V., Tomilov Yu.
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On 3-by-3 row stochastic matrices

Special Matrices, 2023
The known constructive tests for the shapes of the numerical ranges in the 3-by-3 case are further specified when the matrices in question are row stochastic. Auxiliary results on the unitary (ir)reducibility of such matrices are also obtained.
Pham Nhi, Spitkovsky Ilya M.
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On Preserving Properties of Linear Maps on $C^{*}$-algebras [PDF]

Sahand Communications in Mathematical Analysis, 2020
Let $A$ and $B$ be two unital $C^{*}$-algebras and $varphi:A rightarrow B$ be a linear map. In this paper, we investigate the structure of linear maps between two $C^{*}$-algebras that preserve a certain property or relation.
Fatemeh Golfarshchi, Ali Asghar Khalilzadeh   +1 more
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Investigations of the numerical range of a operator matrix

Vestnik Samarskogo Gosudarstvennogo Tehničeskogo Universiteta. Seriâ: Fiziko-Matematičeskie Nauki, 2014
We consider a $2\times2$ operator matrix $A$ (so-called generalized Friedrichs model) associated with a system of at most two quantum particles on ${\rm d}$-dimensional lattice.
Tulkin Kh Rasulov, Elyor B Dilmurodov
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Some results on generalized finite operators and range kernel orthogonality in Hilbert spaces

Demonstratio Mathematica, 2021
Let ℋ{\mathcal{ {\mathcal H} }} be a complex Hilbert space and ℬ(ℋ){\mathcal{ {\mathcal B} }}\left({\mathcal{ {\mathcal H} }}) denotes the algebra of all bounded linear operators acting on ℋ{\mathcal{ {\mathcal H} }}.
Mesbah Nadia, Messaoudene Hadia, Alharbi Asma   +2 more
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Spatial numerical ranges of elements of subalgebras of C0(X)

International Journal of Mathematics and Mathematical Sciences, 2000
When A is a subalgebra of the commutative Banach algebra C0(X) of all continuous complex-valued functions on a locally compact Hausdorff space X, the spatial numerical range of element of A can be described in terms of positive measures.
Sin-Ei Takahasi
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On generalized numerical ranges [PDF]

Pacific Journal of Mathematics, 1976
which ||(T- viyι\\ = l/d(υ, W(T)), v£ CLW(T), where CLW(T) is the closure of the numerical range W(T) of Γ, has been generalized by using the concept of generalized numerical ranges due to C. S. Lin. Also it has been shown that the notions of generalized Minkowski distance functionals and generalized numerical ranges arise in a natural way for elements
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New class of operators where the distance between the identity operator and the generalized Jordan ∗-derivation range is maximal

Demonstratio Mathematica, 2021
A new class of operators, larger than ∗\ast -finite operators, named generalized ∗\ast -finite operators and noted by Gℱ∗(ℋ){{\mathcal{G {\mathcal F} }}}^{\ast }\left({\mathcal{ {\mathcal H} }}) is introduced, where: Gℱ∗(ℋ)={(A,B)∈ℬ(ℋ)×ℬ(ℋ):∥TA−BT∗−λI ...
Messaoudene Hadia, Mesbah Nadia
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