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Krzysztof Rudol

Publications and source records attributed to Krzysztof Rudol.

5 recordsLinked to original sources

General solution of corona problem

Using a description of the spectrum of bidual algebra $A^{**}$ of a uniform algebra $A$ we obtain abstract corona theorem for certain uniform algebras. It asserts the density of a specific Gleason part in the spectrum of an $H^\infty$ -- type subalgebra of $A^{**}$. There is an isometric isomorphism of the latter subalgebra with $H^\infty(G)$ for a wide class of domains $G\subset\mathbb C^d$. Using abstract corona theorem we show the density of the canonical image of $G$ in the spectrum of $H^\infty(G)$, solving positively corona problem for such domains. In particular, we obtain positive solution for balls and polydisks.

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Spectrum of bidual uniform algebras

We obtain a description of the spectrum of bidual algebra $A^{**}$ of a uniform algebra $A$. This spectrum turns out to be a quotient space of the hyper-Stonean envelope of the spectrum of $A$.

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Corona Theorem

For a wide class of domains $G\subset\mathbb C^d$ including balls and polydisks we prove the density of their canonical image in the spectrum of $H^\infty(G)$. This Corona Theorem is proved first in its abstract version for certain uniform algebras. We use properties of bands of measures and idempotents corresponding to Gleason parts. The essential tools are properties of hyper-Stonean spaces, normal and Henkin measures and some ideas based on Hoffman - Rossi theorem. We also use our previous results on weak-star closures of reducing bands of measures. Uniform bounds for operators used to solve the Gleason problem concerning ideals of analytic functions vanishing at given points are applied for bidual algebras.

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A disintegration theorem

A new approach to disintegration of measures is presented, allowing one to drop the usually taken separability assumption. The main tool is a result on fibers in the spectrum of algebra of essentially bounded functions established recently by the first-named author.

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Gleason parts of bidual algebras

It is shown that the embeding of any Gleason part of a uniform algebra into the spectrum of its second dual is an entire Gleason part. This result is based on the equality of weak-star and norm topologies on the Bear-Gleason part.

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