Extreme points of numerical ranges of quasihyponormal operators

It is shown that a quasihypnormal operator on a Hilbert space having 0 as a boundary point of its numerical range is hyponormal. A necessary and sufficient condition is given for the extreme points of the numerical range of a quasihyponormal operator to be eigenvalues. It is also established that if...

Full description

Autores:
Rodríguez Montes, Jaime
Tipo de recurso:
Article of journal
Fecha de publicación:
1993
Institución:
Universidad Nacional de Colombia
Repositorio:
Universidad Nacional de Colombia
Idioma:
spa
OAI Identifier:
oai:repositorio.unal.edu.co:unal/43617
Acceso en línea:
https://repositorio.unal.edu.co/handle/unal/43617
http://bdigital.unal.edu.co/33715/
Palabra clave:
Operator quasihypnormal
Hilbert space
breakpoint
numerical range is hyponormal
Rights
openAccess
License
Atribución-NoComercial 4.0 Internacional
id UNACIONAL2_b81d9c5df74de9df9bda425e85156718
oai_identifier_str oai:repositorio.unal.edu.co:unal/43617
network_acronym_str UNACIONAL2
network_name_str Universidad Nacional de Colombia
repository_id_str
spelling Atribución-NoComercial 4.0 InternacionalDerechos reservados - Universidad Nacional de Colombiahttp://creativecommons.org/licenses/by-nc/4.0/info:eu-repo/semantics/openAccesshttp://purl.org/coar/access_right/c_abf2Rodríguez Montes, Jaime1c6247a1-0750-4b1c-ba45-fb63828bdf1e3002019-06-28T12:12:47Z2019-06-28T12:12:47Z1993https://repositorio.unal.edu.co/handle/unal/43617http://bdigital.unal.edu.co/33715/It is shown that a quasihypnormal operator on a Hilbert space having 0 as a boundary point of its numerical range is hyponormal. A necessary and sufficient condition is given for the extreme points of the numerical range of a quasihyponormal operator to be eigenvalues. It is also established that if T is bounded and there is IIxll = 1 such that IITxll = IITII and that and lt; Tx, x and gt; is a boundary point of the numerical range of T. then T has eigenvalues. Finally, an example is included of a paranormal operator which is not convexoid and such that T -∝ I is not paranormal for certain values of ∝.application/pdfspaUniversidad Nacuional de Colombia; Sociedad Colombiana de matemáticashttp://revistas.unal.edu.co/index.php/recolma/article/view/33605Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de MatemáticasRevista Colombiana de MatemáticasRevista Colombiana de Matemáticas; Vol. 27, núm. 3-4 (1993); 223-230 0034-7426Rodríguez Montes, Jaime (1993) Extreme points of numerical ranges of quasihyponormal operators. Revista Colombiana de Matemáticas; Vol. 27, núm. 3-4 (1993); 223-230 0034-7426 .Extreme points of numerical ranges of quasihyponormal operatorsArtículo de revistainfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501http://purl.org/coar/resource_type/c_2df8fbb1http://purl.org/coar/version/c_970fb48d4fbd8a85Texthttp://purl.org/redcol/resource_type/ARTOperator quasihypnormalHilbert spacebreakpointnumerical range is hyponormalORIGINAL33605-124865-1-PB.pdfapplication/pdf2786710https://repositorio.unal.edu.co/bitstream/unal/43617/1/33605-124865-1-PB.pdfa0bc2fa86d2020857421f2e3949b2628MD51THUMBNAIL33605-124865-1-PB.pdf.jpg33605-124865-1-PB.pdf.jpgGenerated Thumbnailimage/jpeg7434https://repositorio.unal.edu.co/bitstream/unal/43617/2/33605-124865-1-PB.pdf.jpg92922cf3d237773186720ceb94a00366MD52unal/43617oai:repositorio.unal.edu.co:unal/436172023-02-13 23:04:28.897Repositorio Institucional Universidad Nacional de Colombiarepositorio_nal@unal.edu.co
dc.title.spa.fl_str_mv Extreme points of numerical ranges of quasihyponormal operators
title Extreme points of numerical ranges of quasihyponormal operators
spellingShingle Extreme points of numerical ranges of quasihyponormal operators
Operator quasihypnormal
Hilbert space
breakpoint
numerical range is hyponormal
title_short Extreme points of numerical ranges of quasihyponormal operators
title_full Extreme points of numerical ranges of quasihyponormal operators
title_fullStr Extreme points of numerical ranges of quasihyponormal operators
title_full_unstemmed Extreme points of numerical ranges of quasihyponormal operators
title_sort Extreme points of numerical ranges of quasihyponormal operators
dc.creator.fl_str_mv Rodríguez Montes, Jaime
dc.contributor.author.spa.fl_str_mv Rodríguez Montes, Jaime
dc.subject.proposal.spa.fl_str_mv Operator quasihypnormal
Hilbert space
breakpoint
numerical range is hyponormal
topic Operator quasihypnormal
Hilbert space
breakpoint
numerical range is hyponormal
description It is shown that a quasihypnormal operator on a Hilbert space having 0 as a boundary point of its numerical range is hyponormal. A necessary and sufficient condition is given for the extreme points of the numerical range of a quasihyponormal operator to be eigenvalues. It is also established that if T is bounded and there is IIxll = 1 such that IITxll = IITII and that and lt; Tx, x and gt; is a boundary point of the numerical range of T. then T has eigenvalues. Finally, an example is included of a paranormal operator which is not convexoid and such that T -∝ I is not paranormal for certain values of ∝.
publishDate 1993
dc.date.issued.spa.fl_str_mv 1993
dc.date.accessioned.spa.fl_str_mv 2019-06-28T12:12:47Z
dc.date.available.spa.fl_str_mv 2019-06-28T12:12:47Z
dc.type.spa.fl_str_mv Artículo de revista
dc.type.coar.fl_str_mv http://purl.org/coar/resource_type/c_2df8fbb1
dc.type.driver.spa.fl_str_mv info:eu-repo/semantics/article
dc.type.version.spa.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.coar.spa.fl_str_mv http://purl.org/coar/resource_type/c_6501
dc.type.coarversion.spa.fl_str_mv http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.content.spa.fl_str_mv Text
dc.type.redcol.spa.fl_str_mv http://purl.org/redcol/resource_type/ART
format http://purl.org/coar/resource_type/c_6501
status_str publishedVersion
dc.identifier.uri.none.fl_str_mv https://repositorio.unal.edu.co/handle/unal/43617
dc.identifier.eprints.spa.fl_str_mv http://bdigital.unal.edu.co/33715/
url https://repositorio.unal.edu.co/handle/unal/43617
http://bdigital.unal.edu.co/33715/
dc.language.iso.spa.fl_str_mv spa
language spa
dc.relation.spa.fl_str_mv http://revistas.unal.edu.co/index.php/recolma/article/view/33605
dc.relation.ispartof.spa.fl_str_mv Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas
Revista Colombiana de Matemáticas
dc.relation.ispartofseries.none.fl_str_mv Revista Colombiana de Matemáticas; Vol. 27, núm. 3-4 (1993); 223-230 0034-7426
dc.relation.references.spa.fl_str_mv Rodríguez Montes, Jaime (1993) Extreme points of numerical ranges of quasihyponormal operators. Revista Colombiana de Matemáticas; Vol. 27, núm. 3-4 (1993); 223-230 0034-7426 .
dc.rights.spa.fl_str_mv Derechos reservados - Universidad Nacional de Colombia
dc.rights.coar.fl_str_mv http://purl.org/coar/access_right/c_abf2
dc.rights.license.spa.fl_str_mv Atribución-NoComercial 4.0 Internacional
dc.rights.uri.spa.fl_str_mv http://creativecommons.org/licenses/by-nc/4.0/
dc.rights.accessrights.spa.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv Atribución-NoComercial 4.0 Internacional
Derechos reservados - Universidad Nacional de Colombia
http://creativecommons.org/licenses/by-nc/4.0/
http://purl.org/coar/access_right/c_abf2
eu_rights_str_mv openAccess
dc.format.mimetype.spa.fl_str_mv application/pdf
dc.publisher.spa.fl_str_mv Universidad Nacuional de Colombia; Sociedad Colombiana de matemáticas
institution Universidad Nacional de Colombia
bitstream.url.fl_str_mv https://repositorio.unal.edu.co/bitstream/unal/43617/1/33605-124865-1-PB.pdf
https://repositorio.unal.edu.co/bitstream/unal/43617/2/33605-124865-1-PB.pdf.jpg
bitstream.checksum.fl_str_mv a0bc2fa86d2020857421f2e3949b2628
92922cf3d237773186720ceb94a00366
bitstream.checksumAlgorithm.fl_str_mv MD5
MD5
repository.name.fl_str_mv Repositorio Institucional Universidad Nacional de Colombia
repository.mail.fl_str_mv repositorio_nal@unal.edu.co
_version_ 1814089903032500224

Publicaciones similares