The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra

UDC 517.5 We establish the relationship between the S-spectrum of $fg$ and the S-spectrum of $\alpha f+\beta g,$ where $f$ and $g$ are two idempotents on a two-sided quaternionic Banach algebra $\mathcal{A}$ and $\alpha, \beta\in\mathbb{R}.$ We  also study the invertibility of linear combinations of...

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Дата:2026
Автори: Moulaharabbi, Somayya, Barraa, Mohamed
Формат: Стаття
Мова:Англійська
Опубліковано: Institute of Mathematics, NAS of Ukraine 2026
Онлайн доступ:https://umj.imath.kiev.ua/index.php/umj/article/view/8410
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Назва журналу:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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author Moulaharabbi, Somayya
Barraa, Mohamed
Moulaharabbi, Somayya
Barraa, Mohamed
author_facet Moulaharabbi, Somayya
Barraa, Mohamed
Moulaharabbi, Somayya
Barraa, Mohamed
author_sort Moulaharabbi, Somayya
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datestamp_date 2026-03-21T13:35:54Z
description UDC 517.5 We establish the relationship between the S-spectrum of $fg$ and the S-spectrum of $\alpha f+\beta g,$ where $f$ and $g$ are two idempotents on a two-sided quaternionic Banach algebra $\mathcal{A}$ and $\alpha, \beta\in\mathbb{R}.$ We  also study the invertibility of linear combinations of idempotents on $\mathcal{A}.$ To do this, we define the complexification $\mathcal{A}_c$ of $\mathcal{A},$ which is regarded as a real Banach algebra, and establish the relationship between the S-spectrum of $a \in \mathcal{A}$ and the spectrum of $a$ as an element of the complexification $\mathcal{A}_c.$
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spelling umjimathkievua-article-84102026-03-21T13:35:54Z The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra Moulaharabbi, Somayya Barraa, Mohamed Moulaharabbi, Somayya Barraa, Mohamed two-sided quaternionic Banach algebra; Idempotents; S-spectrum UDC 517.5 We establish the relationship between the S-spectrum of $fg$ and the S-spectrum of $\alpha f+\beta g,$ where $f$ and $g$ are two idempotents on a two-sided quaternionic Banach algebra $\mathcal{A}$ and $\alpha, \beta\in\mathbb{R}.$ We  also study the invertibility of linear combinations of idempotents on $\mathcal{A}.$ To do this, we define the complexification $\mathcal{A}_c$ of $\mathcal{A},$ which is regarded as a real Banach algebra, and establish the relationship between the S-spectrum of $a \in \mathcal{A}$ and the spectrum of $a$ as an element of the complexification $\mathcal{A}_c.$ УДК 517.5 S-спектр комбінацій ідемпотентів у двобічній кватерніонній банаховій алгебрі Встановлено зв'язок між S-спектром $fg$ і S-спектром $\alpha f+\beta g,$ де $fg$ – два ідемпотенти з двобічної кватерніонної банахової алгебри $\mathcal{A}$ та $\alpha, \beta \in \mathbb{R}.$  Досліджено також можливість обернення лінійних комбінацій ідемпотентів на $\mathcal{A}.$  З цією метою введено комплексифікацію $\mathcal{A}_c$ алгебри $\mathcal{A},$ яку можна розглядати як дійсну банахову алгебру, та встановлено зв'язок між S-спектром $a \in \mathcal{A}$ і спектром $a$ як елемент комплексифікації $\mathcal{A}_c.$ Institute of Mathematics, NAS of Ukraine 2026-03-21 Article Article https://umj.imath.kiev.ua/index.php/umj/article/view/8410 10.3842/umzh.v77i11.8410 Ukrains’kyi Matematychnyi Zhurnal; Vol. 77 No. 11 (2025); 699–700 Український математичний журнал; Том 77 № 11 (2025); 699–700 1027-3190 en https://umj.imath.kiev.ua/index.php/umj/article/view/8410/10604 Copyright (c) 2025 Somayya Moulaharabbi, Mohamed Barraa
spellingShingle Moulaharabbi, Somayya
Barraa, Mohamed
Moulaharabbi, Somayya
Barraa, Mohamed
The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_alt The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_full The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_fullStr The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_full_unstemmed The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_short The S-spectrum of combinations of idempotents on two-sided quaternionic Banach algebra
title_sort s-spectrum of combinations of idempotents on two-sided quaternionic banach algebra
topic_facet two-sided quaternionic Banach algebra
Idempotents
S-spectrum
url https://umj.imath.kiev.ua/index.php/umj/article/view/8410
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