关于加权三角波雅诺夫-切比雪夫极值问题

IF 0.4 Q4 MATHEMATICS, APPLIED
B'ela Nagy, S. R'ev'esz
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引用次数: 0

摘要

我们研究了三角多项式的加权波雅诺夫-切比雪夫极值问题,即最小化 $\|T\|_{w,C({\mathbb T})}$ 的 minimax 问题,其中 $w$ 是一个充分非消失的、有上界的非负权重函数,规范是环 ${\mathbb T}$ 上相应的加权最大规范,而 $T$ 是具有规定乘数 $\\mathbb T} 的三角多项式、T$ 是三角多项式,根因子 $|\sin(\pi(t-z_j))|^{\nu_j}$ 的规定乘数为 $\nu_1,\ldots,\nu_n$。如果 $\nu_j$ 是自然数,并且它们的和是偶数,那么 $T$ 确实是一个三角多项式,而当所有 $\nu_j$ 都是 1 时,就涉及到了切比雪夫极值问题。我们的结果将更为宽泛,特别是允许所谓的广义三角多项式。为了达到我们的目标,我们引用了芬顿的平移和方法。然而,与前面描述的无权重或在区间上的情况不同,我们在这里发现了不同的情况,并且可以较少地说明解。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
On the weighted trigonometric Bojanov - Chebyshev extremal problem
We investigate the weighted Bojanov-Chebyshev extremal problem for trigonometric polynomials, that is, the minimax problem of minimizing $\|T\|_{w,C({\mathbb T})}$, where $w$ is a sufficiently nonvanishing, upper bounded, nonnegative weight function, the norm is the corresponding weighted maximum norm on the torus ${\mathbb T}$, and $T$ is a trigonometric polynomial with prescribed multiplicities $\nu_1,\ldots,\nu_n$ of root factors $|\sin(\pi(t-z_j))|^{\nu_j}$. If the $\nu_j$ are natural numbers and their sum is even, then $T$ is indeed a trigonometric polynomial and the case when all the $\nu_j$ are 1 covers the Chebyshev extremal problem. Our result will be more general, allowing, in particular, so-called generalized trigonometric polynomials. To reach our goal, we invoke Fenton's sum of translates method. However, altering from the earlier described cases without weight or on the interval, here we find different situations, and can state less about the solutions.
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来源期刊
CiteScore
0.80
自引率
20.00%
发文量
67
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