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hal.structure.identifierInstitut de Mathématiques de Bordeaux [IMB]
dc.contributor.authorZARRABI, Mohamed
dc.date.accessioned2024-04-04T02:19:10Z
dc.date.available2024-04-04T02:19:10Z
dc.date.created2009-03-05
dc.date.issued2013
dc.identifier.issn0022-247X
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/189378
dc.description.abstractEnFor semigroups $S=\R_+, \ \Z_+$ and $\Z_+^k$, we show that if $T$ is a representation of $S$ by contractions on a {\it Hilbert space} then \\ $\inf_{t\in S}\Vert T(t)\widehat f (T)\Vert=\sup\left\{|f(\lambda)|,\ \lambda\in \textrm{Sp}_u (T,S)\right\}$, where $f\in L^1(S)$ and $\text{Sp}_u (T,S)$ is the unitary spectrum of $T$ with respect to $S$. When $T$ is a representation of a suitable semigroup $S$ by contractions on a {\it Banach space}, we give sharp conditions on $\textrm{Sp}_u (T,S)$ which guarantee that the equality above holds. These conditions concern the thinness of $\textrm{Sp}_u (T,S)$ in the harmonic analysis sense. These results are related to theorems of Katzelson-Tzafriri type, which give conditions guaranteeing that $\inf_{t\in S}\Vert T(t)\widehat f (T)\Vert$ vanishes.
dc.description.sponsorship/ - ANR-09-BLAN-0058
dc.language.isoen
dc.publisherElsevier
dc.subject.enRepresentations
dc.subject.enLocally compact abelian group
dc.subject.ensemigroup
dc.subject.encontractions
dc.subject.enspectral synthesis
dc.subject.enHelson set.
dc.subject.enHelson set
dc.title.enSome results of Katznelson-Tzafriri type
dc.typeArticle de revue
dc.identifier.doi10.1016/j.jmaa.2012.07.024
dc.subject.halMathématiques [math]/Analyse fonctionnelle [math.FA]
bordeaux.journalJournal of Mathematical Analysis and Applications
bordeaux.page109-118
bordeaux.volume397
bordeaux.hal.laboratoriesInstitut de Mathématiques de Bordeaux (IMB) - UMR 5251*
bordeaux.issue1
bordeaux.institutionUniversité de Bordeaux
bordeaux.institutionBordeaux INP
bordeaux.institutionCNRS
bordeaux.peerReviewedoui
hal.identifierhal-00461677
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00461677v1
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