Results 11 to 20 of about 92 (86)
A Note on Hyponormal Operators [PDF]
Proceedings of the American Mathematical Society, 1975 A short, elementary proof that a hyponormal operator with a compact imaginary part is normal.
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Commuting hyponormal operators [PDF]
Pacific Journal of Mathematics, 1980 Introduction* Let T be a completely nonunitary contraction on Hubert space such that 1 — T*T has closed range. There exists a power series B(z) = ΣBnzn with operator coefficients which converges and is bounded by one in the unit disk such that T is unitarily equivalent to the difference-quotient transformation in the de Branges-Rovnyak space 3f(B) [1 ...
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A note on 𝑝-hyponormal operators [PDF]
Proceedings of the American Mathematical Society, 1997 Let T T be a p
Cao, Xiaohong, Guo, Maozheng, Meng, Bin
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Boundedly Spaced Subsequences and Weak Dynamics
Journal of Function Spaces, Volume 2018, Issue 1, 2018., 2018 Weak supercyclicity is related to weak stability, which leads to the question that asks whether every weakly supercyclic power bounded operator is weakly stable. This is approached here by investigating weak l‐sequential supercyclicity for Hilbert‐space contractions through Nagy–Foliaş–Langer decomposition, thus reducing the problem to the quest of ...
C. S. Kubrusly +2 more
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On Certain Aspects of the Multidimensional S‐Spectral Theory
Mathematical Problems in Engineering, Volume 2014, Issue 1, 2014., 2014 This paper has two parts. The first one provides the preliminary notions introducing certain general concepts, in order to study, in the second part, the properties of some operator systems which admit spectral residual decompositions, S‐decomposable, S‐spectral, and AS‐scalar systems, and so forth. The results obtained by Frunză, 1975, are generalized,
Cristina Serbanescu +2 more
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Isomorphic Operators and Functional Equations for the Skew‐Circulant Algebra
Abstract and Applied Analysis, Volume 2014, Issue 1, 2014., 2014 The skew‐circulant matrix has been used in solving ordinary differential equations. We prove that the set of skew‐circulants with complex entries has an idempotent basis. On that basis, a skew‐cyclic group of automorphisms and functional equations on the skew‐circulant algebra is introduced.
Zhaolin Jiang +3 more
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On Properties of Class A(n) and n‐Paranormal Operators
Abstract and Applied Analysis, Volume 2014, Issue 1, 2014., 2014 Let n be a positive integer, and an operator T ∈ B(ℋ) is called a class A(n) operator if T1+n2/1+n≥|T|2 and n‐paranormal operator if T1+nx1/1+n≥||Tx|| for every unit vector x ∈ ℋ, which are common generalizations of class A and paranormal, respectively.
Xiaochun Li, Fugen Gao, Changsen Yang
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Cohyponormality of Unbounded Product of Composition Operators in L2 Spaces
Journal of Function Spaces, Volume 2025, Issue 1, 2025.Let X,A,μ be a σ‐finite measure space. The composition operators Cϕ:DCϕ⟶L2μ are defined by Cϕf=f∘ϕ,f∈DCϕ, where ϕ are nonsingular transformations and DCϕ=f∈L2μ: f∘ϕ∈L2μ. Suppose that ϕ1, ϕ2, ⋯, ϕn are nonsingular transformations of X, where n ∈ ℕ and n ≥ 2.
Hang Zhou, Qing Su, Nikhil Khanna
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Hyponormal Toeplitz Operators on the Dirichlet Spaces
Abstract and Applied Analysis, Volume 2013, Issue 1, 2013., 2013 We completely characterize the hyponormality of bounded Toeplitz operators with Sobolev symbols on the Dirichlet space and the harmonic Dirichlet space.
Puyu Cui +2 more
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Quality and Reliability Engineering International, Volume 40, Issue 1, Page 202-219, February 2024.Abstract Laser welding is particularly relevant in the industry thanks to its simplicity, flexibility and final quality. The industry 4.0 and sustainable manufacturing framework gives massive attention to in situ and non‐destructive inspection methods to predict laser weld final quality.
Giacomo Maculotti +2 more
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