On Eigenvalues and Boundary Curvature of the Numerical Rang of Composition Operators on Hardy Space
نویسندگان
چکیده
For a bounded linear operator A on a Hilbert space , let ( ) M A be the smallest possible constant in the inequality ( ) ( ) ( ) p p D A M A R A ≤ . Here, p is a point on the smooth portion of the boundary ( ) W A ∂ of the numerical range of A. ( ) p R A is the radius of curvature of ( ) W A ∂ at this point and ( ) p D A 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 .
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