Results 1 to 10 of about 25 (25)
On hyponormality on a weighted annulus
Open Mathematics, 2021 In this work, we consider the hyponormality of Toeplitz operators on the Bergman space of the annulus with a logarithmic weight. We give necessary conditions when the symbol is of the form φ+ψ¯\varphi +\overline{\psi }, where φ\varphi and ψ\psi are ...
Sadraoui Houcine +2 more
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The Totally Positive Completion Problem: The 3-by-n Case
Special Matrices, 2021 The 3-by-n TP-completable patterns are characterized by identifying the minimal obstructions up to natural symmetries. They are finite in number.
Carter D. +4 more
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Doubly constrained totally positive line insertion
Special Matrices, 2020 It is shown that in any TP matrix, a line (row or column) with two speci˝ed entries in any positions (and the others appropriately chosen) may be inserted in any position, as long as the two entries are consistent with total positivity.
Johnson Charles R., Allen David W.
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A trace bound for integer-diagonal positive semidefinite matrices
Special Matrices, 2020 We prove that an n-by-n complex positive semidefinite matrix of rank r whose graph is connected, whose diagonal entries are integers, and whose non-zero off-diagonal entries have modulus at least one, has trace at least n + r − 1.
Mitchell Lon
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An elementary proof of Chollet’s permanent conjecture for 4 × 4 real matrices
Special Matrices, 2021 A proof of the statement per(A ∘ B) ≤ per(A)per(B) is given for 4 × 4 positive semidefinite real matrices. The proof uses only elementary linear algebra and a rather lengthy series of simple inequalities.
Hutchinson George
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On the similarity to nonnegative and Metzler Hessenberg forms
Special Matrices, 2021 We address the issue of establishing standard forms for nonnegative and Metzler matrices by considering their similarity to nonnegative and Metzler Hessenberg matrices.
Grussler Christian, Rantzer Anders
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Full column rank preservers that preserve semipositivity of matrices
Special Matrices, 2018 Left invertibility preservers on Mm,n(ℝ), m ≥ n, that preserve either semipositivity of matrices or the subset of minimally semipositive matrices are studied. We prove that such maps cannot be degenerate.
Arumugasamy Chandrashekaran +1 more
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Extensions of pseudo-Perron-Frobenius splitting related to generalized inverse AT,S(2)
Special Matrices, 2018 We in this paper define the outer-Perron-Frobenius splitting, which is an extension of the pseudo- Perron-Frobenius splitting defined in [A.N. Sushama, K. Premakumari, K.C.
Huang Shaowu +3 more
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A Hadamard product involving inverse-positive matrices
Special Matrices, 2015 In this paperwe study the Hadamard product of inverse-positive matrices.We observe that this class of matrices is not closed under the Hadamard product, but we show that for a particular sign pattern of the inverse-positive matrices A and B, the Hadamard
Gassó Maria T. +2 more
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A counterexample to the Drury permanent conjecture
Special Matrices, 2017 We offer a counterexample to a conjecture concerning the permanent of positive semidefinite matrices. The counterexample is a 4 × 4 complex correlation matrix.
Hutchinson George
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