Results 11 to 20 of about 865 (99)
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
semanticscholar +2 more sources
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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Cauchy-Schwarz type inequalities and applications to numerical radius inequalities
, 2020 We present new improvements of certain Cauchy–Schwarz type inequalities. As applications of the results obtained, we provide refinements of some numerical radius inequalities for Hilbert space operators. It is shown, among other inequalities, that if A ∈
F. Kittaneh, H. Moradi
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The possible shapes of numerical ranges [PDF]
, 2011 Which convex subsets of the complex plane are the numerical range W(A of some matrix A? This paper gives a precise characterization of these sets. In addition to this we show that for any A there exists a symmetric matrix B of the same size such that W(A)
Helton, J. William, Spitkovsky, Ilya M.
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New norm equalities and inequalities for certain operator matrices
, 2020 We prove new norm equalities and inequalities for general n×n tridiagonal and antitridiagonal operator matrices, including pinching type inequalities for weakly unitarily invariant norms.
Watheq Bani-Domi +2 more
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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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Some new operator inequalities
, 2020 In this article, we present some new inequalities for positive linear mappings that can be viewed as super multiplicative inequalities. As applications, we deduce some numerical radius inequalities.
M. Sababheh +2 more
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The extremal algebra on two hermitians with square 1 [PDF]
, 2002 Let Ea(u,v) be the extremal algebra determined by two hermitians u and v with u2 = v2 = 1. We show that: Ea(u,v) = {f=gu:f,g ε C(T)}, where T is the unit circle; Ea(u,v) is C*-equivelant to C*(G), where G is the infinite dihedral group; most of the
Crabb, M.J., Duncan, J., McGregor, C.M.
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