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arXiv · 2007.01607

Pointwise Remez inequality

B. Eichinger·P. Yuditskii
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Abstract

The standard well-known Remez inequality gives an upper estimate of the values of polynomials on $[-1,1]$ if they are bounded by $1$ on a subset of $[-1,1]$ of fixed Lebesgue measure. The extremal solution is given by the rescaled Chebyshev polynomials for one interval. Andrievskii asked about the maximal value of polynomials at a fixed point, if they are again bounded $1$ on a set of fixed size. We show that the extremal polynomials are either Chebyshev (one interval) or Akhiezer polynomials (two intervals) and prove Totik-Widom bounds for the extremal value, thereby providing a complete asymptotic solution to the Andrievskii problem.

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B. Eichinger, P. Yuditskii. 2020-07-03. Pointwise Remez inequality. https://arxiv.org/abs/2007.01607

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