On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras

In this paper, we investigate the existence of an ultra central approximate identity for a Banach algebra A and its second dual A∗∗. Also, we prove that for a left cancellative regular semigroup S, ℓ1S∗∗ has an ultra central approximate identity if and only if S is a group. As an application, we sho...

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Main Authors: Amir Sahami, Seyedeh Fatemeh Shariati
Format: Article
Language:English
Published: Wiley 2022-01-01
Series:Journal of Mathematics
Online Access:http://dx.doi.org/10.1155/2022/9527678
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author Amir Sahami
Seyedeh Fatemeh Shariati
author_facet Amir Sahami
Seyedeh Fatemeh Shariati
author_sort Amir Sahami
collection DOAJ
description In this paper, we investigate the existence of an ultra central approximate identity for a Banach algebra A and its second dual A∗∗. Also, we prove that for a left cancellative regular semigroup S, ℓ1S∗∗ has an ultra central approximate identity if and only if S is a group. As an application, we show that for a left cancellative semigroup S, ℓ1S∗∗ is pseudo-contractible if and only if S is a finite group. We also study this property for φ-Lau product Banach algebras and the module extension Banach algebras.
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spelling doaj-art-9c18e86a88c84ec38fe12c7017ce98e32025-02-03T06:12:24ZengWileyJournal of Mathematics2314-47852022-01-01202210.1155/2022/9527678On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup AlgebrasAmir Sahami0Seyedeh Fatemeh Shariati1Department of Mathematics Faculty of Basic ScienceDepartment of Mathematics and Computer ScienceIn this paper, we investigate the existence of an ultra central approximate identity for a Banach algebra A and its second dual A∗∗. Also, we prove that for a left cancellative regular semigroup S, ℓ1S∗∗ has an ultra central approximate identity if and only if S is a group. As an application, we show that for a left cancellative semigroup S, ℓ1S∗∗ is pseudo-contractible if and only if S is a finite group. We also study this property for φ-Lau product Banach algebras and the module extension Banach algebras.http://dx.doi.org/10.1155/2022/9527678
spellingShingle Amir Sahami
Seyedeh Fatemeh Shariati
On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
Journal of Mathematics
title On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
title_full On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
title_fullStr On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
title_full_unstemmed On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
title_short On Pseudo-contractibility and Ultra Central Approximate Identity of Some Semigroup Algebras
title_sort on pseudo contractibility and ultra central approximate identity of some semigroup algebras
url http://dx.doi.org/10.1155/2022/9527678
work_keys_str_mv AT amirsahami onpseudocontractibilityandultracentralapproximateidentityofsomesemigroupalgebras
AT seyedehfatemehshariati onpseudocontractibilityandultracentralapproximateidentityofsomesemigroupalgebras