Results 31 to 40 of about 513,360 (262)

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 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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Polynomials and Numerical Ranges [PDF]

Proceedings of the American Mathematical Society, 1988
Let A A be an n × n n \times n complex matrix. For 1 ≤ k ≤ n 1 \leq k \leq n we study the inclusion relation for the following polynomial sets related to the matrix A A . (a) The classical numerical range of the k
openaire   +1 more source

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 numerical ranges and roots

Journal of Mathematical Analysis and Applications, 2003
Let \({\mathfrak a}\) be a complex Banach algebra with unit \(e\). The algebraic numerical range \(V(a)\) of an element \(a\) in \({\mathfrak a}\) is the set \(\{f(a): f\) is a bounded linear functional on \({\mathfrak a}\) such that \(f(e)= \| f\|=1\}\).
Li, Chi-Kwong, Rodman, Leiba, Spitkovsky, Ilya M.   +2 more
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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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On Birkhoff – James and Roberts orthogonality

Special Matrices, 2018
In this paper we present some recent results on characterizations of the Birkhoff-James and the Roberts orthogonality in C*-algebras and Hilbert C*-modules.
Arambašic Ljiljana, Rajic Rajna
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Inverse Numerical Range and Determinantal Quartic Curves

Mathematics, 2020
A hyperbolic ternary form, according to the Helton–Vinnikov theorem, admits a determinantal representation of a linear symmetric matrix pencil. A kernel vector function of the linear symmetric matrix pencil is a solution to the inverse numerical range ...
Mao-Ting Chien, Hiroshi Nakazato
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Volterra operator norms : a brief survey

Moroccan Journal of Pure and Applied Analysis, 2023
In this expository article, we discuss the evaluation and estimation of the operator norms of various functions of the Volterra operator.
Ransford Thomas
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On some reciprocal matrices with elliptical components of their Kippenhahn curves

Special Matrices, 2021
By definition, reciprocal matrices are tridiagonal n-by-n matrices A with constant main diagonal and such that ai,i+1ai+1,i= 1 for i = 1, . . ., n − 1.
Jiang Muyan, Spitkovsky Ilya M.
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