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Pointwise bounded approximation by polynomials. (English) Zbl 0768.30024

Let \(U\) be a bounded open set, and let \(F\) be a closed subset of \(\overline U\). If for each function \(f\), analytic and bounded in \(U\), and each \(\varepsilon>0\) there exists a sequence of polynomials \(p_ m\) such that \(p_ m(z)\to f(z)\) for \(z\in U\), \[ \sup_{z\in U} | p_ m(z)| \leq \sup_{z\in U}| f(z)|, \qquad \sup_{z\in F} | p_ m(z)|\leq \sup_{z\in F\cap U} | f(z)|+ \varepsilon, \] then the authors call \((U,F)\) a Farrell pair. They characterize Farrell pairs and extend a result of A. Stray [Pac. J. Math. 51, 301-305 (1974; Zbl 0288.30035)].
Reviewer: K.Menke (Dortmund)

MSC:

30E10 Approximation in the complex plane

Keywords:

Farrell pairs

Citations:

Zbl 0288.30035
Full Text: DOI

References:

[1] Stray, Pacific J. Math. 51 pp 301– (1974) · Zbl 0288.30035 · doi:10.2140/pjm.1974.51.301
[2] Fisher, Function Theory on Planar Domains (1983) · Zbl 0511.30022
[3] Gamelin, Uniform Algebras (1969)
[4] DOI: 10.1112/plms/s3-51.2.369 · Zbl 0573.30029 · doi:10.1112/plms/s3-51.2.369
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