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JOURNALS // Problemy Analiza — Issues of Analysis // Archive

Probl. Anal. Issues Anal., 2021 Volume 10(28), Issue 3, Pages 71–90 (Mi pa332)

This article is cited in 2 papers

Smirnov's inequality for polynomials having zeros outside the unit disc

E. G. Kompaneets, V. V. Starkov

Petrozavodsk State University, 33 Lenina pr., Petrozavodsk 185910, Russia

Abstract: In 1887, the famous chemist D. I. Mendeleev posed the following problem: to estimate $|f'(x)|$ for a real polynomial $f(x)$, satisfying the condition $|f(x)|\leq M$ on $[a, b]$. This question arose when Mendeleev was studying aqueous solutions. The problem was solved by the famous mathematician A. A. Markov, and over the following 100 years was repeatedly modified and extended. For complex polynomials, important inequalities were obtained by S. N. Bernstein and V. I. Smirnov. Many other well-known mathematicians, such as Ch. Pommerenke, G. Szegö, Q. I. Rahman, G. Schmeisser, worked in this subject. Almost all results in this direction significantly use the following condition: all zeros of a majorizing polynomial belong to the closed unit disc. In this paper, we remove this condition. Here a majorizing polynomial may have zeros outside the unit disc. This allows to extend the inequalities of Bernstein and Smirnov.

Keywords: polynomial, the Smirnov inequality, the Bernstein inequality.

UDC: 517.53

MSC: 30C10, 30A10

Received: 11.09.2021
Revised: 28.09.2021
Accepted: 23.10.2021

Language: English

DOI: 10.15393/j3.art.2021.10970



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