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On Eigenvalues and Boundary Curvature of the Numerical Rang of Composition Operators on Hardy Space
Department of Mathematics, College of Sciences, Yasouj University, Yasouj, Iran
- 1 Department of Mathematics, College of Sciences, Yasouj University, Yasouj, Iran
Advances in Pure Mathematics·Volume 05 (2015)·Pages 333–337·Published 5 May 2015·DOI10.4236/apm.2015.56032
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Abstract
For a bounded linear operator A on a Hilbert spac e H , let M(A) be the smallest possible constant in the inequality . Here , p is a point on the smooth portion of the boundary of the numerical range of A . is the radius of curvature of at this point and is the distance from p to the spectrum of A . In this paper , we compute the M(A) for composition operators on Hardy space H 2.
KeywordsComposition OperatorNumerical RangeEigenvaluesCurvature
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