Results 1 to 10 of about 499 (74)
Further refinements of some numerical radius inequalities for operators
Operators and Matrices, 2023 . In this work, we give re fi nements of some well-known numerical radius inequalities. Also, we present an improvement of the triangle inequality for the operator norm. Mathematics subject classi fi cation (2020): 47A12, 47A30, 47B15.
Soumia Soltani, Abdelkader Frakis
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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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Preservers of the c-numerical radius of operator jordan semi-triple products
Operators and Matrices, 2021 Let H be a complex Hilbert space with dimH 3 , let B(H ) be the algebra of all bounded linear operators on H and let Bs(H ) be the real Jordan algebra of all self-adjoint operators in B(H ) . Let A = B(H ) or Bs(H ) .
Y. Zhang, X. Fang
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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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A Chain of numerical radius inequalities in complex Hilbert space
Journal of Mathematical Inequalities, 2021 In this paper, we implement the improvement of numerical radius inequalities that were produced by Alomari MW. [Refinements of some numerical radius inequalities for Hilbert space operators. Linear and Multilinear Algebra.
Mohammed Al-Dolat +2 more
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On partial isometries with circular numerical range
Concrete Operators, 2021 In their LAMA 2016 paper Gau, Wang and Wu conjectured that a partial isometry A acting on ℂn cannot have a circular numerical range with a non-zero center, and proved this conjecture for n ≤ 4. We prove it for operators with rank A = n − 1 and any n.
Wegert Elias, Spitkovsky Ilya
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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 +2 more
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Common fixed points for weak commutative mappings on a multiplicative metric space
Fixed Point Theory and Applications, 2014 In this paper, we discuss the unique common fixed point of two pairs of weak commutative mappings on a complete multiplicative metric space. They satisfy the following inequality: d(Sx,Ty)≤{max{d(Ax,By),d(Ax,Sx),d(By,Ty),d(Sx,By),d(Ax,Ty)}}λ, where A and
Xiaoju He, Meimei Song, D. Chen
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The Numerical Range of C*ψ Cφ and Cφ C*ψ
Concrete Operators, 2021 In this paper we investigate the numerical range of C*bφm Caφn and Caφn C*bφm on the Hardy space where φ is an inner function fixing the origin and a and b are points in the open unit disc.
Clifford John +2 more
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Refinements of numerical radius inequalities using the Kantorovich ratio
Concrete Operators, 2022 In this paper, we improve some numerical radius inequalities for Hilbert space operators under suitable condition. We also compare our results with some known results. As application of our result, we obtain an operator inequality.
Nikzat Elham, Omidvar Mohsen Erfanian
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