A note about the norm of the sum and the anticommutator of two orthogonal projections

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Autor principal: Conde, Cristian Marcelo
Formato: Artículo publishedVersion
Lenguaje:Inglés
Publicado: Elsevier Science 2025
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Acceso en línea:http://repositorio.ungs.edu.ar:8080/xmlui/handle/UNGS/2328
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spelling I71-R177-UNGS-23282025-07-24T18:00:32Z A note about the norm of the sum and the anticommutator of two orthogonal projections Conde, Cristian Marcelo Orthogonal Projection Norm Inequalities Commutator Anticommutator Proyección ortogonal Desigualdades normativas Matemáticas Matemática Pura Revista con referato Fil: Conde, Cristian Marcelo. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Fil: Conde, Cristian Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Matemática Alberto Calderón; Argentina. En esta nota, demostramos que, para dos proyecciones ortogonales cualesquiera PT,PS sobre un Hilbert, las conocidas fórmulas normativas ?PT+PS?=1+?PTPS?, a menos que PT=PS=0 y ?PTPS+PSPT?=?PTPS?2+?PTPS?, pueden derivarse entre sí. Este resultado se obtiene a partir de la relación entre los espectros de la suma y el producto de dos idempotentes cualesquiera en un álgebra de Banach. Se presentan aplicaciones de nuestros resultados. In this note, we prove that for any two orthogonal projections PT,PS on a Hilbert the well-known norm formulas ?PT+PS?=1+?PTPS?, unless PT=PS=0 and ?PTPS+PSPT?=?PTPS?2+?PTPS?, can be derived from each other. Such result is obtained from the relation between the spectra of the sum and product of any two idempotents in a Banach algebra. Applications of our results are given. 2025-07-24T18:00:32Z 2025-07-24T18:00:32Z 2022 info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion Conde, C. M. (2022). A note about the norm of the sum and the anticommutator of two orthogonal projections. Journal of Mathematical Analysis and Applications, 505(2), 1-11. 0022-247X http://repositorio.ungs.edu.ar:8080/xmlui/handle/UNGS/2328 eng http://dx.doi.org/10.1016/j.jmaa.2021.125650 info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf application/pdf Elsevier Science Journal of Mathematical Analysis and Applications. Ene-2022; 505(2): 1-11 https://www.sciencedirect.com/journal/journal-of-mathematical-analysis-and-applications/vol/505/issue/2
institution Universidad Nacional de General Sarmiento
institution_str I-71
repository_str R-177
collection Repositorio Institucional Digital de Acceso Abierto (UNGS)
language Inglés
orig_language_str_mv eng
topic Orthogonal Projection
Norm Inequalities
Commutator
Anticommutator
Proyección ortogonal
Desigualdades normativas
Matemáticas
Matemática Pura
spellingShingle Orthogonal Projection
Norm Inequalities
Commutator
Anticommutator
Proyección ortogonal
Desigualdades normativas
Matemáticas
Matemática Pura
Conde, Cristian Marcelo
A note about the norm of the sum and the anticommutator of two orthogonal projections
topic_facet Orthogonal Projection
Norm Inequalities
Commutator
Anticommutator
Proyección ortogonal
Desigualdades normativas
Matemáticas
Matemática Pura
description Revista con referato
format Artículo
Artículo
publishedVersion
author Conde, Cristian Marcelo
author_facet Conde, Cristian Marcelo
author_sort Conde, Cristian Marcelo
title A note about the norm of the sum and the anticommutator of two orthogonal projections
title_short A note about the norm of the sum and the anticommutator of two orthogonal projections
title_full A note about the norm of the sum and the anticommutator of two orthogonal projections
title_fullStr A note about the norm of the sum and the anticommutator of two orthogonal projections
title_full_unstemmed A note about the norm of the sum and the anticommutator of two orthogonal projections
title_sort note about the norm of the sum and the anticommutator of two orthogonal projections
publisher Elsevier Science
publishDate 2025
url http://repositorio.ungs.edu.ar:8080/xmlui/handle/UNGS/2328
work_keys_str_mv AT condecristianmarcelo anoteaboutthenormofthesumandtheanticommutatoroftwoorthogonalprojections
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