Value Sharing and Stirling Numbers

被引:0
作者
Hinkkanen, Aimo [1 ]
Laine, Ilpo [2 ]
机构
[1] Univ Illinois, Dept Math, Urbana, IL 61801 USA
[2] Univ Eastern Finland, Dept Phys & Math, Joensuu 80100, Finland
关键词
Uniqueness theory; Linear differential polynomials; Stirling numbers;
D O I
10.1007/s40315-024-00552-5
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Let f be an entire function and L(f) a linear differential polynomial in f with constant coefficients. Suppose that f, f '\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$f'$$\end{document}, and L(f) share a meromorphic function alpha(z)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha (z)$$\end{document} that is a small function with respect to f. A characterization of the possibilities that may arise was recently obtained by Lahiri. However, one case leaves open many possibilities. We show that this case has more structure than might have been expected, and that a more detailed study of this case involves, among other things, Stirling numbers of the first and second kinds. We prove that the function alpha\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha $$\end{document} must satisfy a linear homogeneous differential equation with specific coefficients involving only three free parameters, and then f can be obtained from each solution. Examples suggest that only rarely do single-valued solutions alpha(z)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha (z)$$\end{document} exist, and even then they are not always small functions for f.
引用
收藏
页码:631 / 660
页数:30
相关论文
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