Inner Functions in Lipschitz, Besov, and Sobolev Spaces

We study the membership of inner functions in Besov, Lipschitz, and Hardy-Sobolev spaces, finding conditions that enable an inner function to be in one of these spaces. Several results in this direction are given that complement or extend previous works on the subject from different authors. In part...

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Main Authors: Daniel Girela, Cristóbal González, Miroljub Jevtić
Format: Article
Language:English
Published: Wiley 2011-01-01
Series:Abstract and Applied Analysis
Online Access:http://dx.doi.org/10.1155/2011/626254
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author Daniel Girela
Cristóbal González
Miroljub Jevtić
author_facet Daniel Girela
Cristóbal González
Miroljub Jevtić
author_sort Daniel Girela
collection DOAJ
description We study the membership of inner functions in Besov, Lipschitz, and Hardy-Sobolev spaces, finding conditions that enable an inner function to be in one of these spaces. Several results in this direction are given that complement or extend previous works on the subject from different authors. In particular, we prove that the only inner functions in either any of the Hardy-Sobolev spaces Hαp with 1/p≤α<∞ or any of the Besov spaces Bαp,  q with 0<p,q≤∞ and α≥1/p, except when p=∞, α=0, and 2<q≤∞ or when 0<p<∞, q=∞, and α=1/p are finite Blaschke products. Our assertion for the spaces B0∞,q, 0<q≤2, follows from the fact that they are included in the space VMOA. We prove also that for 2<q<∞, VMOA is not contained in B0∞,q and that this space contains infinite Blaschke products. Furthermore, we obtain distinct results for other values of α relating the membership of an inner function I in the spaces under consideration with the distribution of the sequences of preimages {I-1(a)}, |a|<1. In addition, we include a section devoted to Blaschke products with zeros in a Stolz angle.
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spelling doaj-art-b85295d8f8b04936a31a9dd18e291c932025-02-03T07:24:38ZengWileyAbstract and Applied Analysis1085-33751687-04092011-01-01201110.1155/2011/626254626254Inner Functions in Lipschitz, Besov, and Sobolev SpacesDaniel Girela0Cristóbal González1Miroljub Jevtić2Departamento de Análisis Matemático, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, SpainDepartamento de Análisis Matemático, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, SpainMatematički Fakultet, University of Belgrade, PP. 550, 11000 Belgrade, SerbiaWe study the membership of inner functions in Besov, Lipschitz, and Hardy-Sobolev spaces, finding conditions that enable an inner function to be in one of these spaces. Several results in this direction are given that complement or extend previous works on the subject from different authors. In particular, we prove that the only inner functions in either any of the Hardy-Sobolev spaces Hαp with 1/p≤α<∞ or any of the Besov spaces Bαp,  q with 0<p,q≤∞ and α≥1/p, except when p=∞, α=0, and 2<q≤∞ or when 0<p<∞, q=∞, and α=1/p are finite Blaschke products. Our assertion for the spaces B0∞,q, 0<q≤2, follows from the fact that they are included in the space VMOA. We prove also that for 2<q<∞, VMOA is not contained in B0∞,q and that this space contains infinite Blaschke products. Furthermore, we obtain distinct results for other values of α relating the membership of an inner function I in the spaces under consideration with the distribution of the sequences of preimages {I-1(a)}, |a|<1. In addition, we include a section devoted to Blaschke products with zeros in a Stolz angle.http://dx.doi.org/10.1155/2011/626254
spellingShingle Daniel Girela
Cristóbal González
Miroljub Jevtić
Inner Functions in Lipschitz, Besov, and Sobolev Spaces
Abstract and Applied Analysis
title Inner Functions in Lipschitz, Besov, and Sobolev Spaces
title_full Inner Functions in Lipschitz, Besov, and Sobolev Spaces
title_fullStr Inner Functions in Lipschitz, Besov, and Sobolev Spaces
title_full_unstemmed Inner Functions in Lipschitz, Besov, and Sobolev Spaces
title_short Inner Functions in Lipschitz, Besov, and Sobolev Spaces
title_sort inner functions in lipschitz besov and sobolev spaces
url http://dx.doi.org/10.1155/2011/626254
work_keys_str_mv AT danielgirela innerfunctionsinlipschitzbesovandsobolevspaces
AT cristobalgonzalez innerfunctionsinlipschitzbesovandsobolevspaces
AT miroljubjevtic innerfunctionsinlipschitzbesovandsobolevspaces