期刊论文详细信息
Concrete Operators
The Numerical Range of C*ψ Cφ and Cφ C*ψ
Wiggins Alan1  Dabkowski Michael1  Clifford John1 
[1] Department of Mathematics and Statistics, University of Michigan-Dearborn, Dearborn, MI, 48128, USA;
关键词: composition operator;    numerical range;    inner function;    weighted shift;    47b33;    47a12;    15a60;   
DOI  :  10.1515/conop-2020-0108
来源: DOAJ
【 摘 要 】

In this paper we investigate the numerical range of C*bφm Caφn and Caφn C*bφm on the Hardy space where φ is an inner function fixing the origin and a and b are points in the open unit disc. In the case when |a| = |b| = 1 we characterize the numerical range of these operators by constructing lacunary polynomials of unit norm whose image under the quadratic form incrementally foliate the numerical range. In the case when a and b are small we show numerical range of both operators is equal to the numerical range of the operator restricted to a 3-dimensional subspace.

【 授权许可】

Unknown   

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