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Related papers: Widom Factors and Szeg\H{o}-Widom Asymptotics, a R…

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We study the behavior of weighted residual polynomials on circular arcs, including weighted Chebyshev polynomials. For weights given by reciprocals of polynomials, we establish Szeg\H{o}-Widom asymptotics. Extending our analysis to less…

Complex Variables · Mathematics 2026-02-06 Jacob S. Christiansen , Benjamin Eichinger , Olof Rubin , Maxim Zinchenko

We derive optimal asymptotic and non-asymptotic lower bounds on the Widom factors for weighted Chebyshev and orthogonal polynomials on compact subsets of the real line. In the Chebyshev case we extend the optimal non-asymptotic lower bound…

Classical Analysis and ODEs · Mathematics 2024-08-22 Gökalp Alpan , Maxim Zinchenko

We study weighted Chebyshev polynomials on compact subsets of the complex plane with respect to a bounded weight function. We establish existence and uniqueness of weighted Chebyshev polynomials and derive weighted analogs of Kolmogorov's…

Complex Variables · Mathematics 2025-08-13 Galen Novello , Klaus Schiefermayr , Maxim Zinchenko

We make a number of comments on Chebyshev polynomials for general compact subsets of the complex plane. We focus on two aspects: asymptotics of the zeros and explicit Totik--Widom upper bounds on their norms.

Classical Analysis and ODEs · Mathematics 2018-12-31 Jacob S. Christiansen , Barry Simon , Maxim Zinchenko

We prove Szeg\H{o}-Widom asymptotics for the Chebyshev polynomials of a compact subset of $\mathbb{R}$ which is regular for potential theory and obeys the Parreau-Widom and DCT conditions.

Classical Analysis and ODEs · Mathematics 2019-03-20 Jacob S. Christiansen , Barry Simon , Peter Yuditskii , Maxim Zinchenko

We determine which sets saturate the Szeg}o and Schiefermayr lower bounds on the norms of Chebyshev Polynomials. We also discuss sets that saturate the Totik--Widom upper bound.

Classical Analysis and ODEs · Mathematics 2017-12-12 Jacob S. Christiansen , Barry Simon , Maxim Zinchenko

We study residual polynomials, $R_{x_0,n}^{(\mathfrak{e})}$, $\mathfrak{e}\subset\mathbb{R}$, $x_0\in\mathbb{R}\setminus\mathfrak{e}$, which are the degree at most $n$ polynomials with $R(x_0)=1$ that minimize the $\sup$ norm on…

Classical Analysis and ODEs · Mathematics 2020-08-25 Jacob S. Christiansen , Barry Simon , Maxim Zinchenko

We consider Chebyshev polynomials, $T_n(z)$, for infinite, compact sets $\frak{e} \subset \mathbb{R}$ (that is, the monic polynomials minimizing the sup-norm, $\Vert T_n \Vert_{\frak{e}}$, on $\frak{e}$). We resolve a $45+$ year old…

Classical Analysis and ODEs · Mathematics 2019-11-06 Jacob S. Christiansen , Barry Simon , Maxim Zinchenko

We give upper and lower bounds for weighted Chebyshev and residual polynomials on subsets of the real line. As an application, we prove a Szeg\H{o}-type theorem in the setting of Parreau--Widom sets.

Classical Analysis and ODEs · Mathematics 2025-02-18 Jacob S. Christiansen , Barry Simon , Maxim Zinchenko

We investigate Chebyshev polynomials corresponding to Jacobi weights and determine monotonicity properties of their related Widom factors. This complements work by Bernstein from 1930-31 where the asymptotical behavior of the related…

Classical Analysis and ODEs · Mathematics 2024-09-05 Jacob S. Christiansen , Olof Rubin

There is a vast theory of Chebyshev and residual polynomials and their asymptotic behavior. The former ones maximize the leading coefficient and the latter ones maximize the point evaluation with respect to an $L^\infty$ norm. We study…

Classical Analysis and ODEs · Mathematics 2021-01-07 Benjamin Eichinger , Milivoje Lukić , Giorgio Young

Thiran and Detaille give an explicit formula for the asymptotics of the sup-norm of the Chebyshev polynomials on a circular arc. We give the so-called $\textrm{Szeg\H o}$-Widom asymptotics for this domain, i.e., explicit expressions for the…

Classical Analysis and ODEs · Mathematics 2016-07-26 Benjamin Eichinger

This article examines the asymptotic behavior of the Widom factors, denoted $\mathcal{W}_n$, for Chebyshev polynomials of finite unions of Jordan arcs. We prove that, in contrast to Widom's proposal, when dealing with a single smooth Jordan…

Classical Analysis and ODEs · Mathematics 2023-12-21 Jacob S. Christiansen , Benjamin Eichinger , Olof Rubin

In this paper we present a survey about analytic properties of polynomials orthogonal with respect to a weighted Sobolev inner product such that the vector of measures has an unbounded support. In particular, we are focused in the study of…

Classical Analysis and ODEs · Mathematics 2011-11-10 Francisco Marcellan , Juan Jose Moreno-Balcazar

In 1969 Harold Widom published his seminal paper, which gave a complete description of orthogonal and Chebyshev polynomials on a system of smooth Jordan curves. When there were Jordan arcs present the theory of orthogonal polynomials turned…

Classical Analysis and ODEs · Mathematics 2014-01-27 Vilmos Totik , Peter Yuditskii

We continue to investigate some classes of Szeg\"o type polynomials in several variables. We focus on asymptotic properties of these polynomials and we extend several classical results of G. Szeg\"o to this setting.

Functional Analysis · Mathematics 2007-05-23 M. Barakat , T. Constantinescu

We continue studying polynomials generated by the Szeg\H{o} recursion when a finite number of Verblunsky coefficients lie outside the closed unit disk. We prove some asymptotic results for the corresponding orthogonal polynomials and then…

Classical Analysis and ODEs · Mathematics 2017-06-29 Maxim Derevyagin , Brian Simanek

We generalize the theory of Widom factors to the $\mathbb C^n$ setting. We define Widom factors of compact subsets $K\subset \mathbb C^n$ associated with multivariate orthogonal polynomials and weighted Chebyshev polynomials. We show that…

Complex Variables · Mathematics 2025-12-19 Gökalp Alpan , Turgay Bayraktar , Norm Levenberg

We study optimal lower and upper bounds for Widom factors $W_{\infty,n}(K,w)$ associated with Chebyshev polynomials for the weights $w(x)=\sqrt{1+x}$ and $w(x)=\sqrt{1-x}$ on compact subsets of $[-1,1]$. We show which sets saturate these…

Classical Analysis and ODEs · Mathematics 2021-07-29 Gökalp Alpan

We continue our study of the Widom factors for $L_p(\mu)$ extremal polynomials initiated in [4]. In this work we characterize sets for which the lower bounds obtained in [4] are saturated, establish continuity of the Widom factors with…

Classical Analysis and ODEs · Mathematics 2020-05-20 Gökalp Alpan , Maxim Zinchenko
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