Constrained von Neumann inequalities
Type de document :
Compte-rendu et recension critique d'ouvrage
Titre :
Constrained von Neumann inequalities
Auteur(s) :
Badea, Catalin [Auteur]
Laboratoire Paul Painlevé - UMR 8524 [LPP]
Cassier, Gilles [Auteur]
Institut Girard Desargues [IGD]
Laboratoire Paul Painlevé - UMR 8524 [LPP]
Cassier, Gilles [Auteur]
Institut Girard Desargues [IGD]
Titre de la revue :
Advances in Mathematics
Pagination :
260-297
Éditeur :
Elsevier
Date de publication :
2002
ISSN :
0001-8708
Discipline(s) HAL :
Mathématiques [math]/Analyse fonctionnelle [math.FA]
Résumé en anglais : [en]
An equivalent formulation of the von Neumann inequality states that the backward shift $S^*$ on $\\ell_{2}$ is extremal, in the sense that if $T$ is a Hilbert space contraction, then $\\|p(T)\\| \\leq \\|p(S^*)\\|$ for ...
Lire la suite >An equivalent formulation of the von Neumann inequality states that the backward shift $S^*$ on $\\ell_{2}$ is extremal, in the sense that if $T$ is a Hilbert space contraction, then $\\|p(T)\\| \\leq \\|p(S^*)\\|$ for each polynomial $p$. We discuss several results of the following type : if $T$ is a Hilbert space contraction satisfying some constraints, then $S^*$ restricted to a suitable invariant subspace is an extremal operator. Several operator radii are used instead of the operator norm. Applications to inequalities of coefficients of rational functions positive on the torus are given.Lire moins >
Lire la suite >An equivalent formulation of the von Neumann inequality states that the backward shift $S^*$ on $\\ell_{2}$ is extremal, in the sense that if $T$ is a Hilbert space contraction, then $\\|p(T)\\| \\leq \\|p(S^*)\\|$ for each polynomial $p$. We discuss several results of the following type : if $T$ is a Hilbert space contraction satisfying some constraints, then $S^*$ restricted to a suitable invariant subspace is an extremal operator. Several operator radii are used instead of the operator norm. Applications to inequalities of coefficients of rational functions positive on the torus are given.Lire moins >
Langue :
Anglais
Vulgarisation :
Non
Commentaire :
Preprint version
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