On some properties of Banach operators

A mapping α from a normed space X into itself is called a Banach operator if there is a constant k such that 0≤k<1 and ‖α2(x)−α(x)‖≤k‖α(x)−x‖ for all x∈X. In this note we study some properties of Banach operators. Among other results we show that if α is a linear Banach operator on a normed spac...

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Main Authors: A. B. Thaheem, AbdulRahim Khan
Format: Article
Language:English
Published: Wiley 2001-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S0161171201006251
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author A. B. Thaheem
AbdulRahim Khan
author_facet A. B. Thaheem
AbdulRahim Khan
author_sort A. B. Thaheem
collection DOAJ
description A mapping α from a normed space X into itself is called a Banach operator if there is a constant k such that 0≤k<1 and ‖α2(x)−α(x)‖≤k‖α(x)−x‖ for all x∈X. In this note we study some properties of Banach operators. Among other results we show that if α is a linear Banach operator on a normed space X, then N(α−1)=N((α−1)2), N(α−1)∩R(α−1)=(0) and if X is finite dimensional then X=N(α−1)⊕R(α−1), where N(α−1) and R(α−1) denote the null space and the range space of (α−1), respectively and 1 is the identity mapping on X. We also obtain some commutativity results for a pair of bounded linear multiplicative Banach operators on normed algebras.
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spelling doaj-art-94034e637a5d434588c9a30f5f69dd232025-02-03T05:44:16ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04252001-01-0127314915310.1155/S0161171201006251On some properties of Banach operatorsA. B. Thaheem0AbdulRahim Khan1Department of Mathematical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi ArabiaDepartment of Mathematical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi ArabiaA mapping α from a normed space X into itself is called a Banach operator if there is a constant k such that 0≤k<1 and ‖α2(x)−α(x)‖≤k‖α(x)−x‖ for all x∈X. In this note we study some properties of Banach operators. Among other results we show that if α is a linear Banach operator on a normed space X, then N(α−1)=N((α−1)2), N(α−1)∩R(α−1)=(0) and if X is finite dimensional then X=N(α−1)⊕R(α−1), where N(α−1) and R(α−1) denote the null space and the range space of (α−1), respectively and 1 is the identity mapping on X. We also obtain some commutativity results for a pair of bounded linear multiplicative Banach operators on normed algebras.http://dx.doi.org/10.1155/S0161171201006251
spellingShingle A. B. Thaheem
AbdulRahim Khan
On some properties of Banach operators
International Journal of Mathematics and Mathematical Sciences
title On some properties of Banach operators
title_full On some properties of Banach operators
title_fullStr On some properties of Banach operators
title_full_unstemmed On some properties of Banach operators
title_short On some properties of Banach operators
title_sort on some properties of banach operators
url http://dx.doi.org/10.1155/S0161171201006251
work_keys_str_mv AT abthaheem onsomepropertiesofbanachoperators
AT abdulrahimkhan onsomepropertiesofbanachoperators