The Numerical Ranges of Automorphic Comp
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Paul S. Bourdon; Joel H. Shapiro
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Article
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2000
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Elsevier Science
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English
β 136 KB
We investigate the shape of the numerical range for composition operators induced on the Hardy space H 2 by conformal automorphisms of the unit disc. We show that usually, but not always, such operators have numerical ranges whose closures are discs centered at the origin. Surprising open questions