论文标题

在选举中的多项式上

On Suffridge polynomials

论文作者

Dillies, Jimmy, Dmitrishin, Dmitriy, Stokolos, Alex

论文摘要

我们考虑了Ted Suffridge于1969年引入的多项式家族的一些已知和一些新属性。首先,我们简要概述了它们在经典和最新工作中的极端特性。我们还为Sublidge多项式提供了一个紧凑的形式,该表格与Brandt发现的一般模式相匹配。我们的方法使我们能够找到Brandt结果没有明确给出的系数。这种新的演讲为我们提供了通过单价多项式估算广义KOEBE函数近似速率的工具。此外,我们考虑了罗伯逊(Robertson)形式的裁定多项式的介绍,并找到了适合的罗伯逊措施。这提出了一种通过连续单调的近似步骤函数的新方法。然后,我们研究了这些多项式的无关性的鲁棒性,并提出了一个新的多项式家庭,我们猜测了子类的无关。也就是说,我们证明了一个非常令人惊讶的事实,即通过扩展家庭,通过让多项式系数中的离散论点扩展成为连续的,这不会增加一组单价多项式。只有初始多项式保持单位。在这个新的一个参数家族中,概括了多项式,值得注意的是,参考式多项式已经是极端的,因为它们对应于选择的参数设置为1;此外,复杂的fejér多项式对应于参数设置为0的选择,而参数设置为-1的选择对应于多项式$ z+(z^n/n)$。值得注意的是,计算机模拟似乎清楚地表明,这些新的多项式映射下的单位光盘的图像是一个简单连接的区域,该区域由简单的曲线界定。这证明了这些多项式对整个参数范围的猜想。

We consider some known and some new properties of the family of polynomials introduced by Ted Suffridge in 1969. We begin by giving a brief overview of their extremal properties in classic and more recent work. We also give a compact form for Suffridge polynomials which matches a general pattern discovered by Brandt. Our approach allows us to find the coefficients which Brandt's result was not giving explicitly. This new presentation provides us the tools to obtain an estimate of the rate of approximation of the generalized Koebe functions by univalent polynomials. Furthermore, we consider the presentation of Suffridge polynomials in Robertson's form and find the suiting Robertson measure. This suggests a new way to approximate step functions by continuous monotonic ones. We then study the lack of robustness of the univalency of these polynomials and suggest a new family of polynomials for which we conjecture the univalency of a subclass. Namely, we prove the quite surprising fact that by extending the family by letting the discrete argument in the polynomial coefficients become continuous one does not increase the set of univalent polynomials. Only the initial polynomials remain univalent. In this new one parameter family generalizing the Suffridge polynomials, it is remarkable that the Suffridge polynomials are already extremal as they correspond to the choice of the parameter set to 1; moreover the complex Fejér polynomials correspond the choice of the parameter set to 0, and the choice of the parameter set to -1 corresponds the polynomials $z+(z^N/N)$. Remarkably, computer simulations seem to clearly indicate that the image of the unit disc under these new polynomial mapping is a simply-connected region bounded by a simple curve. This justifies the conjectural univalency of these polynomials for the whole range of the parameters.

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