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On uniform approximation by \(n\)-analytic functions on closed sets in \(\mathbb C\). (English. Russian original) Zbl 1069.30076

Izv. Math. 68, No. 3, 447-459 (2004); translation from Izv. Ross. Akad. Nauk Ser. Mat. 68, No. 3, 15-28 (2004).
Let \(n\) be a positive integer. A function \(f\) is called \(n\)-analytic on an open set \(G\) in the complex plane if \(f\in C^n(G)\) and \(\bar{\partial}^nf=0\) in \(G\). Such a function has a unique representation \[ f(z)=f_0(z)+\bar{z}f_1(z)+\dots +\bar{z}^{n-1}f_{n-1}(z), \] where \(f_0,f_1,\dots f_{n-1}\) are holomorphic functions on \(G\). The authors provide necessary and/or sufficient conditions on a closed set \(F\) for any function \(f\) continuous on \(F\) and \(n\)-analytic in the interior of \(F\), to be the uniform limit on \(F\) of a sequence of \(n\)-analytic entire or meromorphic functions. The proofs involve the notions of Carathéodory and Nevanlinna domains, and the classical approximation theorems (Mergelyan, Arakelyan etc).

MSC:

30G30 Other generalizations of analytic functions (including abstract-valued functions)
30E10 Approximation in the complex plane
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