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On the Extreme Points of Quotients of L∞ by Douglas Algebras

Published online by Cambridge University Press:  20 November 2018

Waleed Deeb  and
Rahman Younis
Waleed Deeb
Affiliation:
Kuwait University, Kuwait
Rahman Younis
Affiliation:
Kuwait University, Kuwait
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Abstract

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Let B be a Douglas algebra which admits best approximation. It will be shown that the following are equivalent: (1) The unit ball of (L∞/B) has no extreme points; (2) For any Blaschke product b with , there exists h ∈ B such that = 1 and h|E≢0, where E is the essential set of B.

It will also be proven that if B⊇H∞+C and its essential set E contains a closed Gδ set, then the unit ball of (L∞/B) has no extreme points. Many known results concerning this subject will follow from these results.

Keywords

30H0546E1541A50

Information

Type
Research Article
Information
Canadian Mathematical Bulletin , Volume 27 , Issue 4 , 01 December 1984 , pp. 517 - 522
Copyright
Copyright © Canadian Mathematical Society 1984

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