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This article is cited in 4 scientific papers (total in 4 papers)
Haar problem for sign-sensitive approximations
E. A. Sevast'yanov Moscow Institute of Municipal Economy and Construction
Abstract:
The Haar problem for sign-sensitive approximations consists in finding necessary and sufficient conditions for a finite-dimensional subspace $L$ of the space $C(E)$ of continuous functions on a compact subset $E$ of $\mathbb R$ and a sign-sensitive weight $p(x)=\bigl (p_-(x),p_+(x)\bigr )$, $x \in E$, ensuring that for each function $f$ in $L$ there exists a unique element of best approximation with weight $p$. Several conditions of this kind are established. These conditions are shown to be closely connected with the topological properties of the annihilators of the functions $p_-(x)$ and $p_+(x)$. In particular, the sign-sensitive weights $p=(p_-,p_+)$ are described such that the same condition as the one introduced by Haar for uniform approximations (that is, for $p(x) \equiv (1,1)$) serves the corresponding Haar problem.
Received: 13.09.1995
Citation:
E. A. Sevast'yanov, “Haar problem for sign-sensitive approximations”, Mat. Sb., 188:2 (1997), 95–128; Sb. Math., 188:2 (1997), 265–297
Linking options:
https://www.mathnet.ru/eng/sm203https://doi.org/10.1070/sm1997v188n02ABEH000203 https://www.mathnet.ru/eng/sm/v188/i2/p95
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Abstract page: | 507 | Russian version PDF: | 219 | English version PDF: | 22 | References: | 91 | First page: | 1 |
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