On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras

Axiomatic Fredholm theory in unital C*-algebras was established in [D. Kečkić, Z. Lazović, Acta Sci. Math., 83(3-4):629--655, 2017]. Following the pure algebraic approach by Kečkić and Lazović, in the author's paper [S. Ivković, Banach J. Math. Anal., 17:51, 2023] we extended further this theor...

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Main Author: Stefan Ivkovic
Format: Article
Language:English
Published: Odesa National University of Technology 2024-02-01
Series:Pracì Mìžnarodnogo Geometričnogo Centru
Subjects:
Online Access:https://journals.ontu.edu.ua/index.php/geometry/article/view/2594
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author Stefan Ivkovic
author_facet Stefan Ivkovic
author_sort Stefan Ivkovic
collection DOAJ
description Axiomatic Fredholm theory in unital C*-algebras was established in [D. Kečkić, Z. Lazović, Acta Sci. Math., 83(3-4):629--655, 2017]. Following the pure algebraic approach by Kečkić and Lazović, in the author's paper [S. Ivković, Banach J. Math. Anal., 17:51, 2023] we extended further this theory to axiomatic semi-Fredholm and semi-Weyl theory in unital C*-algebras. However, recently, in [S. Ivković, arXiv:2306.01133] we developed another approach to axiomatic Fredholm theory in unital C*-algebras which is based on the theory of Hilbert modules and is equivalent to the algebraic approach by Kečkić and Lazović. In this paper, we extend further that new Hilbert-module approach from Fredholm theory to semi-Fredholm and semi-Weyl theory in unital C*-algebras. Hence, we provide new proofs to the results in [S. Ivković, Banach J. Math. Anal., 17:51, 2023].
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spelling doaj.art-6e564b6fc3f444e0b83f5e26188cdc322024-02-19T08:47:40ZengOdesa National University of TechnologyPracì Mìžnarodnogo Geometričnogo Centru2072-98122409-89062024-02-0117111710.15673/pigc.v17i1.25942594On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebrasStefan Ivkovic0Mathematical Institute of the Serbian Academy of Sciences and ArtsAxiomatic Fredholm theory in unital C*-algebras was established in [D. Kečkić, Z. Lazović, Acta Sci. Math., 83(3-4):629--655, 2017]. Following the pure algebraic approach by Kečkić and Lazović, in the author's paper [S. Ivković, Banach J. Math. Anal., 17:51, 2023] we extended further this theory to axiomatic semi-Fredholm and semi-Weyl theory in unital C*-algebras. However, recently, in [S. Ivković, arXiv:2306.01133] we developed another approach to axiomatic Fredholm theory in unital C*-algebras which is based on the theory of Hilbert modules and is equivalent to the algebraic approach by Kečkić and Lazović. In this paper, we extend further that new Hilbert-module approach from Fredholm theory to semi-Fredholm and semi-Weyl theory in unital C*-algebras. Hence, we provide new proofs to the results in [S. Ivković, Banach J. Math. Anal., 17:51, 2023].https://journals.ontu.edu.ua/index.php/geometry/article/view/2594semi-fredholm operatorsemi-weyl operatorindexk-grouphilbert module
spellingShingle Stefan Ivkovic
On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
Pracì Mìžnarodnogo Geometričnogo Centru
semi-fredholm operator
semi-weyl operator
index
k-group
hilbert module
title On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
title_full On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
title_fullStr On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
title_full_unstemmed On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
title_short On new approach to semi-Fredholm theory in unital C<sup>*</sup>-algebras
title_sort on new approach to semi fredholm theory in unital c sup sup algebras
topic semi-fredholm operator
semi-weyl operator
index
k-group
hilbert module
url https://journals.ontu.edu.ua/index.php/geometry/article/view/2594
work_keys_str_mv AT stefanivkovic onnewapproachtosemifredholmtheoryinunitalcsupsupalgebras