A Solution to a Problem of Rubel on Two-Parameter Normal Families of Entire Functions

Fuente: arXiv
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Auteurs principaux: He, Yixin, Tang, Quanyu, Zhang, Teng
Format: Preprint
Publié: 2026
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author He, Yixin
Tang, Quanyu
Zhang, Teng
author_facet He, Yixin
Tang, Quanyu
Zhang, Teng
contents We construct an entire function $ F(z,a,b)\in \mathcal{O}(\mathbb{C}^3) $ such that the family $$ \{F(\,\cdot\,,a,b):a,b\in\mathbb{C}\} $$ of entire functions of \(z\) is normal on \(\mathbb{C}\), while \(F\) does not factor through a single entire parameter. This solves a problem of L.~A.~Rubel concerning Liouville-type rigidity. In fact, our example satisfies the stronger condition $$ F_bF_{a,z}-F_aF_{b,z}\neq 0 \qquad\text{on }\mathbb{C}^3. $$ The geometric core of the construction is a Fatou--Bieberbach domain contained in the thin region $$ \{(u,v)\in\mathbb{C}^2:|u-v^2|<1+|v|\}. $$ We obtain this domain from the basin of attraction of an explicit polynomial automorphism of \(\mathbb{C}^2\), together with the theorem of Rosay and Rudin on attracting basins.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20883
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Solution to a Problem of Rubel on Two-Parameter Normal Families of Entire Functions
He, Yixin
Tang, Quanyu
Zhang, Teng
Complex Variables
30D45, 32A19, 32M17
We construct an entire function $ F(z,a,b)\in \mathcal{O}(\mathbb{C}^3) $ such that the family $$ \{F(\,\cdot\,,a,b):a,b\in\mathbb{C}\} $$ of entire functions of \(z\) is normal on \(\mathbb{C}\), while \(F\) does not factor through a single entire parameter. This solves a problem of L.~A.~Rubel concerning Liouville-type rigidity. In fact, our example satisfies the stronger condition $$ F_bF_{a,z}-F_aF_{b,z}\neq 0 \qquad\text{on }\mathbb{C}^3. $$ The geometric core of the construction is a Fatou--Bieberbach domain contained in the thin region $$ \{(u,v)\in\mathbb{C}^2:|u-v^2|<1+|v|\}. $$ We obtain this domain from the basin of attraction of an explicit polynomial automorphism of \(\mathbb{C}^2\), together with the theorem of Rosay and Rudin on attracting basins.
title A Solution to a Problem of Rubel on Two-Parameter Normal Families of Entire Functions
topic Complex Variables
30D45, 32A19, 32M17
url https://arxiv.org/abs/2603.20883