Some discrepancy theorems in the theory of weighted polynomial approximation (Q1269663)

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scientific article; zbMATH DE number 1215738
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Some discrepancy theorems in the theory of weighted polynomial approximation
scientific article; zbMATH DE number 1215738

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    Some discrepancy theorems in the theory of weighted polynomial approximation (English)
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    27 July 1999
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    The authors generalize discrepancy results in the theory of distribution of zeros of extremal polynomials appearing in the theory of weighted polynomial approximation on the real line. It is a very technical paper, making it practically impossible to give the main results explicitly in a review. They are concerned with bounds \[ \left| \nu(P)(I)-\lambda^{\ast}_n(I)\right| \leq c {\log C_n\over n}\log\left({n\over \log C_n}\right) \] and \[ \left| \nu({\mathcal T}_{n,p,Q})(I)-\lambda^{\ast}_n(I)\right| \leq c{(\log n)^2\over n}. \] Here \(\nu\) can be seen as the counting measure and \(\lambda^{\ast}\) plays the role of the equilibrium measure. The function \(Q\) satisfies several technical conditions and the polynomials \({\mathcal T}_{n,p,Q}\) (\(1<p\leq \infty)\) are a type of Chebyshev polynomials with respect to a weight function \(W_Q\).
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    weighted polynomial approximation
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    distribution of zeros
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    discrepancy
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