Results 1 to 10 of about 100 (42)
REMARKS ON EMBEDDABLE SEMIGROUPS IN GROUPS AND A GENERALIZATION OF SOME CUTHBERT'S RESULTS
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 22, Page 1421-1431, 2003., 2003 Let (U(t))t≥0 be a C0-semigroup of bounded linear operators on a Banach space X. In this paper, we establish that if, for some t0 > 0, U(t0) is a Fredholm (resp., semiFredholm) operator, then (U(t))t≥0 is a Fredholm (resp., semi-Fredholm) semigroup ...
K. Latrach, Abdelkader Dehici
semanticscholar +2 more sources
On a conjecture by Mbekhta about best approximation by polar factors [PDF]
, 2021 The polar factor of a bounded operator acting on a Hilbert space is the unique partial isometry arising in the polar decomposition. It is well known that the polar factor might not be a best approximant to its associated operator in the set of all ...
E. Chiumiento
semanticscholar +1 more source
The g-Drazin inverses of special operator matrices
Operators and Matrices, 2021 An element a in a Banach algebra A has g-Drazin inverse provided that there exists b ∈ A such that b = bab , ab = ba , a− a2b ∈ A qnil . In this paper we give a computational formula for the g-Drazin inverse of operator matrix ( E I F 0 ) which was posed
Hua Chen, M. Abdolyousefi
semanticscholar +1 more source
Generalized lower characteristic involving measures of non-strict singularity
Topological Algebra and its Applications, 2023 This work establishes a connection between the class of generalized lower characteristic operators and [⋅]a{\left[\cdot ]}_{a} acting on a Banach space involving measures of non-strict singularity.
Baraket Sami +2 more
doaj +1 more source
B-Fredholm elements in primitive C*-algebras
Open Mathematics, 2022 Let A{\mathcal{A}} be a unital primitive C∗\ast -algebra. This article studies the properties of the B-Fredholm elements, the B-Weyl elements and the B-Browder elements in A{\mathcal{A}}. Particularly, this article describes the B-Fredholm element as the
Kong Yingying, Jiang Lining
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Syrian crisis repercussions on the agricultural sector: Case study of wheat, cotton and olives
Regional Science Policy &Practice, Volume 12, Issue 3, Page 519-537, June 2020., 2020 Abstract This paper aims to outline the consequences of the Syrian conflict on the land use/cultivated area, yield and production of the main crops: wheat, cotton, and olives. To achieve the study goal secondary data were collected from FAO website. After that the autoregressive integrated moving average (ARIMA) model was applied for the time series ...
Safwan A. Mohammed +3 more
wiley +1 more source
On new strong versions of Browder type theorems
Open Mathematics, 2018 An operator T acting on a Banach space X satisfies the property (UWΠ) if σa(T)∖ σSF+−$\begin{array}{} \sigma_{SF_{+}^{-}} \end{array} $(T) = Π(T), where σa(T) is the approximate point spectrum of T, σSF+−$\begin{array}{} \sigma_{SF_{+}^{-}} \end{array} $
Sanabria José +4 more
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On the essential spectra of unbounded operator matrices with non diagonal domain and an application
Operators and Matrices, 2019 This paper is devoted to the investigation of the spectral stability of unbounded operator matrices with non diagonal domain in product of Banach spaces.
Marwa Belghith, N. Moalla, I. Walha
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Parity as Z2‐valued spectral flow
Bulletin of the London Mathematical Society, Volume 51, Issue 5, Page 836-852, October 2019., 2019 Abstract This note is about the topology of the path space of linear Fredholm operators on a real Hilbert space. Fitzpatrick and Pejsachowicz introduced the parity of such a path, based on the Leray–Schauder degree of a path of parametrices. Here an alternative analytic approach is presented which reduces the parity to the Z2‐valued spectral flow of an
Nora Doll +2 more
wiley +1 more source
On the closed range problem for composition operators on the Dirichlet space
Concrete Operators, 2019 We characterize closed range composition operators on the Dirichlet space for a particular class of composition symbols. The characterization relies on a result about Fredholm Toeplitz operators with BMO1 symbols, and with Berezin transforms of vanishing
Zorboska Nina
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