Cauchy transform and uniform approximation by polynomial modules

被引:0
|
作者
Yang, Liming [1 ]
机构
[1] Virginia Polytech Inst & State Univ, Dept Math, Blacksburg, VA 24061 USA
关键词
Analytic capacity; Cauchy transform; Polynomial modulus; ANALYTIC CAPACITY; SEMIADDITIVITY;
D O I
10.1016/j.jmaa.2023.127004
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
For a compact subset K of the complex plane C, let C(K) denote the algebra of continuous functions on K. For an open subset U C K, let A(K, U) C C(K) be the algebra of functions that are analytic in U. We show that there exists phi E A(K, U) so that each f E A(K, U) can uniformly be approximated by {pn + qn phi} on K, where pn and qn are analytic polynomials in z. In particular, phi can be chosen as a Cauchy transform of a finite positive measure eta compactly supported in C \ U. Recent developments of analytic capacity and Cauchy transform provide us useful tools in our proofs.
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页数:21
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