The Bishop–Phelps–Bollobás Property and Absolute Sums
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DOI: 10.1007/s00009-019-1346-6
Abstract: In this paper, we study conditions assuring that the Bishop–Phelps–Bollobás property (BPBp, for short) is inherited by absolute summands of the range space or of the domain space. Concretely, given a pair (X, Y) of Banach… read more here.
Keywords: bishop phelps; bollob property; phelps bollob; numerical radius ... See more keywords
On the Compact Operators Case of the Bishop–Phelps–Bollobás Property for Numerical Radius
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DOI: 10.1007/s00025-021-01430-5
Abstract: We study the Bishop–Phelps–Bollobas property for numerical radius restricted to the case of compact operators (BPBp-nu for compact operators in short). We show that $$C_0(L)$$ spaces have the BPBp-nu for compact operators for every Hausdorff… read more here.
Keywords: bpbp compact; property; compact operators; property numerical ... See more keywords
Numerical radius attaining compact linear operators
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DOI: 10.1016/j.jmaa.2016.02.074
Abstract: Abstract We show that there are compact linear operators on Banach spaces which cannot be approximated by numerical radius attaining operators. read more here.
Keywords: compact linear; radius attaining; numerical radius; attaining compact ... See more keywords
Equality of three numerical radius inequalities
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DOI: 10.1016/j.laa.2018.05.021
Abstract: Abstract For an n-by-n matrix A, let w ( A ) and ‖ A ‖ denote its numerical radius and operator norm, respectively. The following three inequalities, each a strengthening of w ( A )… read more here.
Keywords: three numerical; radius; radius inequalities; numerical radius ... See more keywords
A-numerical radius inequalities for semi-Hilbertian space operators
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DOI: 10.1016/j.laa.2019.05.012
Abstract: Let $A$ be a positive bounded operator on a Hilbert space $\big(\mathcal{H}, \langle \cdot, \cdot\rangle \big)$. The semi-inner product ${\langle x, y\rangle}_A := \langle Ax, y\rangle$, $x, y\in\mathcal{H}$ induces a semi-norm ${\|\cdot\|}_A$ on $\mathcal{H}$. Let… read more here.
Keywords: numerical radius; space; semi hilbertian; hilbertian space ... See more keywords
Another generalization of the numerical radius for Hilbert space operators
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DOI: 10.1016/j.laa.2020.08.032
Abstract: Abstract Let B ( H ) be the C ⁎ -algebra of all bounded linear operators on a Hilbert space H . Let N ( ⋅ ) be an arbitrary norm on B ( H… read more here.
Keywords: space; hilbert space; another generalization; numerical radius ... See more keywords
On Numerical Radius Inequalities for Operator Matrices
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DOI: 10.1080/01630563.2018.1549073
Abstract: Abstract The aim of this article is to prove several new numerical radius inequalities for n × n operator matrices on a Hilbert space. Let be complex Hilbert spaces, and let be an n × n operator matrix with… read more here.
Keywords: radius; radius inequalities; operator matrices; numerical radius ... See more keywords
On some numerical radius inequalities for normal operators in Hilbert spaces
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DOI: 10.1080/09720502.2021.1930658
Abstract: Abstract Let T be a normal bounded operator on a Hilbert space and let ω(T) denote the numerical radius of T. In this paper, we give new inequalities numerical radius of normal operatos on a… read more here.
Keywords: normal operators; numerical radius; radius inequalities; operators hilbert ... See more keywords
Refinements of norm and numerical radius inequalities
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DOI: 10.1216/rmj.2021.51.1953
Abstract: Several refinements of norm and numerical radius inequalities of bounded linear operators on a complex Hilbert space are given. In particular, we show that if $A$ is a bounded linear operator on a complex Hilbert… read more here.
Keywords: numerical radius; leq; frac; bigg ... See more keywords
Generalizations of numerical radius inequalities related to block matrices
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DOI: 10.2298/fil1915981b
Abstract: We establish several numerical radius inequalities related to 2x2 positive semidefinite block matrices. It is shown that if A,B,C ? Mn(C) are such that [A B* B C] ? 0, then wr(B)? 1/2 ||Ar +… read more here.
Keywords: block matrices; inequalities related; numerical radius; radius inequalities ... See more keywords
Some inequalities involving Hilbert-Schmidt numerical radius on 2 x 2 operator matrices
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DOI: 10.2298/fil2014649h
Abstract: We present some inequalities related to the Hilbert-Schmidt numerical radius of 2 x 2 operator matrices. More precisely, we present a formula for the Hilbert-Schmidt numerical radius of an operator as follows: w2(T) = sup… read more here.
Keywords: radius operator; hilbert schmidt; schmidt numerical; numerical radius ... See more keywords