单位球内整体函数和解析函数的组成

IF 1 Q1 MATHEMATICS
Andriy Ivanovych Bandura, O. Skaskiv, I. Tymkiv
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引用次数: 1

摘要

本文研究了单位球中若干复变量全函数与解析函数的组合。我们对早期已知的结果进行了修正,给出了这种组合在一个方向上$L$ -index的有界性和一元初始函数$l$ -index的有界性的等价条件,其中连续函数$L:\mathbb{B}^n\to \mathbb{R}_+$由连续函数$l: \mathbb{C}^m\to \mathbb{R}_+.$构造,考虑到最近关于整个函数组合的结果的新思想,我们去掉了复合函数中内部函数$\Phi$的方向导数不等于零的条件。与此条件不同,我们构造了一个更大的函数$L(z)$,其中$F(z)=f(\underbrace{\Phi(z),\ldots,\Phi(z)}_{m\text{ times}})$在一个方向上具有有界的$L$ -索引,其中$f\colon \mathbb{C}^m\to \mathbb{C}$是在$(1,\ldots,1)$方向上有界的$l$ -索引的完整函数,$\Phi\colon \mathbb{B}^n\to \mathbb{C}$是单位球中的解析函数。我们对所有的$z\in\mathbb{B}^n$弱化条件$|\partial_{\mathbf{b}}^k\Phi(z)|\le K|\partial_{\mathbf{b}}\Phi(z)|^k$,其中$K\geq 1$是一个常数,$\mathbf{b}\in\mathbb{C}^n\setminus\{0\}$是一个给定的方向,$${\partial_{\mathbf{b}} F(z)}:=\sum\limits_{j=1}^{n}\!\frac{\partial F(z)}{\partial z_{j}}{b_{j}}, \ \partial_{\mathbf{b}}^k F(z):=\partial_{\mathbf{b}}\big(\partial_{\mathbf{b}}^{k-1} F(z)\big).$$被条件$|\partial_{\mathbf{b}}^k\Phi(z)|\le K(l(\Phi(z)))^{1/(N_{\mathbf{1}}(f,l)+1)}|\partial_{\mathbf{b}}\Phi(z)|^k$所取代,其中$N_{\mathbf{1}}(f,l)$是$f$函数在$\mathbf{1}=(1,\ldots,1).$方向上的$l$索引。对于一维情况$n=1,$$m=1$,即单位圆盘中的解析函数$\Phi$和有界$l$ -索引的整个函数$f: \mathbb{C}\to\mathbb{C}$,也是一个新的结果。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Composition of entire and analytic functions in the unit ball
In this paper, we investigate a composition of entire function of several complex variables and analytic function in the unit ball. We modified early known results with conditions providing equivalence of boundedness of $L$-index in a direction for such a composition and boundedness of $l$-index of initial function of one variable, where the continuous function $L:\mathbb{B}^n\to \mathbb{R}_+$ is constructed by the continuous function $l: \mathbb{C}^m\to \mathbb{R}_+.$ Taking into account new ideas from recent results on composition of entire functions, we remove a condition that a directional derivative of the inner function $\Phi$ in the composition does not equal to zero. Instead of the condition we construct a greater function $L(z)$ for which $F(z)=f(\underbrace{\Phi(z),\ldots,\Phi(z)}_{m\text{ times}})$ has bounded $L$-index in a direction, where $f\colon \mathbb{C}^m\to \mathbb{C}$ is an entire function of bounded $l$-index in the direction $(1,\ldots,1)$, $\Phi\colon \mathbb{B}^n\to \mathbb{C}$ is an analytic function in the unit ball. We weaken the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K|\partial_{\mathbf{b}}\Phi(z)|^k$ for all $z\in\mathbb{B}^n$, where $K\geq 1$ is a constant, $\mathbf{b}\in\mathbb{C}^n\setminus\{0\}$ is a given direction and $${\partial_{\mathbf{b}} F(z)}:=\sum\limits_{j=1}^{n}\!\frac{\partial F(z)}{\partial z_{j}}{b_{j}}, \ \partial_{\mathbf{b}}^k F(z):=\partial_{\mathbf{b}}\big(\partial_{\mathbf{b}}^{k-1} F(z)\big).$$ It is replaced by the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K(l(\Phi(z)))^{1/(N_{\mathbf{1}}(f,l)+1)}|\partial_{\mathbf{b}}\Phi(z)|^k$, where $N_{\mathbf{1}}(f,l)$ is the $l$-index of the function $f$ in the direction $\mathbf{1}=(1,\ldots,1).$ The described result is an improvement of previous one. It is also a new result for the one-dimensional case $n=1,$ $m=1$, i.e. for an analytic function $\Phi$ in the unit disc and for an entire function $f: \mathbb{C}\to\mathbb{C}$ of bounded $l$-index.
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来源期刊
CiteScore
1.90
自引率
12.50%
发文量
31
审稿时长
25 weeks
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