Maximal subalgebra of Douglas algebra

When q is an interpolating Blaschke product, we find necessary and sufficient conditions for a subalgebra B of H∞[q¯] to be a maximal subalgebra in terms of the nonanalytic points of the noninvertible interpolating Blaschke products in B. If the set M(B)⋂Z(q) is not open in Z(q), we also find a cond...

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Main Author: Carroll J. Gullory
Format: Article
Language:English
Published: Wiley 1988-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Subjects:
Online Access:http://dx.doi.org/10.1155/S0161171288000894
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author Carroll J. Gullory
author_facet Carroll J. Gullory
author_sort Carroll J. Gullory
collection DOAJ
description When q is an interpolating Blaschke product, we find necessary and sufficient conditions for a subalgebra B of H∞[q¯] to be a maximal subalgebra in terms of the nonanalytic points of the noninvertible interpolating Blaschke products in B. If the set M(B)⋂Z(q) is not open in Z(q), we also find a condition that guarantees the existence of a factor q0 of q in H∞ such that B is maximal in H∞[q¯]. We also give conditions that show when two arbitrary Douglas algebras A and B, with A⫅B have property that A is maximal in B.
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spelling doaj-art-61ec6336ce9b4fc38ea8f55c94677a822025-02-03T01:02:09ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251988-01-0111473574110.1155/S0161171288000894Maximal subalgebra of Douglas algebraCarroll J. Gullory0Department of Mathematics, University of Southwestern Louisiana, Lafayette 70504, Louisiana, USAWhen q is an interpolating Blaschke product, we find necessary and sufficient conditions for a subalgebra B of H∞[q¯] to be a maximal subalgebra in terms of the nonanalytic points of the noninvertible interpolating Blaschke products in B. If the set M(B)⋂Z(q) is not open in Z(q), we also find a condition that guarantees the existence of a factor q0 of q in H∞ such that B is maximal in H∞[q¯]. We also give conditions that show when two arbitrary Douglas algebras A and B, with A⫅B have property that A is maximal in B.http://dx.doi.org/10.1155/S0161171288000894maximal subalgebraDouglas algebrainterpolating sequencesparse sequenceBlaschke productinner functionsopen and closed subsetnonanalytic pointssupport setQ−C level sets.
spellingShingle Carroll J. Gullory
Maximal subalgebra of Douglas algebra
International Journal of Mathematics and Mathematical Sciences
maximal subalgebra
Douglas algebra
interpolating sequence
sparse sequence
Blaschke product
inner functions
open and closed subset
nonanalytic points
support set
Q−C level sets.
title Maximal subalgebra of Douglas algebra
title_full Maximal subalgebra of Douglas algebra
title_fullStr Maximal subalgebra of Douglas algebra
title_full_unstemmed Maximal subalgebra of Douglas algebra
title_short Maximal subalgebra of Douglas algebra
title_sort maximal subalgebra of douglas algebra
topic maximal subalgebra
Douglas algebra
interpolating sequence
sparse sequence
Blaschke product
inner functions
open and closed subset
nonanalytic points
support set
Q−C level sets.
url http://dx.doi.org/10.1155/S0161171288000894
work_keys_str_mv AT carrolljgullory maximalsubalgebraofdouglasalgebra