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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Mathematische Annale...arrow_drop_down
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
Mathematische Annalen
Article . 1995 . Peer-reviewed
License: Springer TDM
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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
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The generalized corona theorem

Authors: Gorkin, P.; Mortini, R.; Nicolau, A.;

The generalized corona theorem

Abstract

This is another beautiful paper on the ideal theory of \(H^\infty\) by one of the leading experts (R.M.) and colleagues. \(H^\infty\) is the ring of bounded holomorphic functions in the open unit disk \(\mathbb{D}\). For \(f_1,\dots, f_N\in H^\infty\), \(J:= \{f\in H^\infty: |f|\leq C_f \sum^N_{j= 1} |f_j|\), for some finite constant \(C_f\}\) is an ideal that contains the ideal \(I\) generated by \(f_1,\dots, f_N\), and simple examples show that proper containment can occur. L. Carleson's famous Corona Theorem asserts that equality occurs if \(J= H^\infty\). It is proved that if \(N= 2\) and \(f_1\), \(f_2\) have no common non-invertible \(H^\infty\)-factor, then \(I= J\) if and only if either \(I\) or \(J\) contains an interpolating Blaschke product. [Earlier work of \textit{V. Tolokonnikov} is relevant, especially J. Soc. Math. 27, 2549-2553 (1984; Zbl 0546.46046).] But for \(N= 3\) an (easy) example is constructed of \(I= J\) without this ideal containing an interpolating Blaschke product. Denote by \(M\) the maximal ideal space of \(H^\infty\), and by \(\widehat f: M\to \mathbb{C}\) the Gelfand transform of \(f\in H^\infty\). The order of \(m\in M\) as a zero of \(\widehat f\) is defined in a natural way and the minimum of these over \(f\in I\), denoted \(\text{ord}(I, m)\), plays a significant role. Use is made of an earlier result of the second author's [Analysis 14, No. 1, 67-73 (1984; Zbl 0810.46055)]that an ideal \(I\subsetneqq H^\infty\) is generated by interpolating Blaschke products if and only if \(\text{ord}(I, m)\in \{0, 1\}\) for every \(m\in M\). Thomas Wolff showed some time ago that \(f\in J\) implies \(f^3\in I\) always holds, and he posed the problem [cf. Lect. Notes Math. 1043 (1984; Zbl 0545.30038)] whether the stronger conclusion \(f^2\in I\) always holds as well. In the second part of this paper, the authors provide an affirmative answer under the additional assumption that at every \(m\in M\), \(\text{ord}(\widehat f_j, m)\) is finite for at least one \(j\in \{1,\dots, N\}\); this hypothesis is (nontrivially) equivalent to the \(\widehat f_j\) not all vanishing at any one-point Gleason part in \(M\). The methods used are the standard ones developed by Wolff for proving the Corona theorem and involve Carleson measures, CN (= Carleson-Newman)- sequences and CN-Blaschke products.

Country
Germany
Keywords

finitely generated ideals, interpolating Blaschke product, Gelfand transform, Blaschke products, etc., Ideals, maximal ideals, boundaries, Article, \(H^p\)-classes, maximal ideal space, zero sets, 510.mathematics, Banach algebras of differentiable or analytic functions, \(H^p\)-spaces, ring of bounded holomorphic functions, Corona Theorem, ideal theory of \(H^ \infty\), Carleson measures, one-point Gleason part

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
7
Average
Top 10%
Average
Green