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arXiv 1505.02415math.CV
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有限Blaschke积与有理$Γ$ -内函数的构造

Finite Blaschke products and the construction of rational $Γ$-inner functions

Jim Agler, Zinaida A. Lykova, N. J. Young

摘要:

设\[ Γ= \{(z+w, zw): |z|\leq 1, |w|\leq 1\} \subset \mathbb{C}^2. \],定义$Γ$ -内函数为从单位圆$\mathbb{D}$到$Γ$的全纯映射$h$,其在单位圆$\mathbb{T}$上几乎所有点的边界值都属于$Γ$的区别边界$bΓ$.有理$Γ$ -内函数$h$导出从单位圆到$bΓ$的连续映射$h|_\mathbb{T}$.后一个集合在拓扑上是莫比乌斯带,因此具有基本群$\mathbb{Z}$。定义$h$的{ \em度}为$h|_\mathbb{T}$的拓扑度。在以前的论文中,作者表明,如果$h=(s,p)$是一个合理的$Γ$ -内部功能的程度$n$然后$s^2-4p$有正是$n$零在封闭的单位光盘$\mathbb{D}^-$,计数与适当的概念的多重性。本文借助于有限Blaschke积的一个插值问题的解,利用$s^2-4p$的$n$零点和$s$的相应值,明确地构造了有理$Γ$ -内函数$n$.

英文摘要:

Let \[ Γ= \{(z+w, zw): |z|\leq 1, |w|\leq 1\} \subset \mathbb{C}^2. \] A $Γ$-inner function is defined to be a holomorphic map $h$ from the unit disc $\mathbb{D}$ to $Γ$ whose boundary values at almost all points of the unit circle $\mathbb{T}$ belong to the distinguished boundary $bΓ$ of $Γ$. A rational $Γ$-inner function $h$ induces a continuous map $h|_\mathbb{T}$ from the unit circle to $bΓ$. The latter set is topologically a Möbius band and so has fundamental group $\mathbb{Z}$. The {\em degree} of $h$ is defined to be the topological degree of $h|_\mathbb{T}$. In a previous paper the authors showed that if $h=(s,p)$ is a rational $Γ$-inner function of degree $n$ then $s^2-4p$ has exactly $n$ zeros in the closed unit disc $\mathbb{D}^-$, counted with an appropriate notion of multiplicity. In this paper, with the aid of a solution of an interpolation problem for finite Blaschke products, we explicitly construct the rational $Γ$-inner functions of degree $n$ with the $n$ zeros of $s^2-4p$ and the corresponding values of $s$, prescribed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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