Normal families of holomorphic functions
Chang, Jianming ; Fang, Mingliang ; Zalcman, Lawrence
Illinois J. Math., Tome 48 (2004) no. 3, p. 319-337 / Harvested from Project Euclid
Let $\mathcal{F}$ be a family of holomorphic functions in a domain $D$; let $k$ be a positive integer; let $h$ be a positive number; and let $a$ be a function holomorphic in $D$ such that $a(z)\not= 0$ for $z\in D$. For $k\not= 2$ we show that if, for every $f\in \mathcal{F}$, all zeros of $f$ have multiplicity at least $ k$, $f(z)=0$ $\Longrightarrow $ $f^{(k)}(z)=a(z)$, and $f^{(k)}(z)=a(z)$ $\Longrightarrow $ $|f^{(k+1)}(z)|\le h$, then $\mathcal{F}$ is normal in $D$. For $k=2$ we prove the following result: Let $s\ge 4$ be an even integer. If, for every $f\in \mathcal{F}$, all zeros of $f$ have multiplicity at least $ 2$, $f(z)=0$ $\Longrightarrow $ $f''(z)=a(z)$, and $f''(z)=a(z)$ $\Longrightarrow $ $|f'''(z)|+|f^{(s)}(z)|\le h$, then $\mathcal{F}$ is normal in $D$. This improves the well-known normality criterion of Miranda.
Publié le : 2004-01-15
Classification:  30D45
@article{1258136186,
     author = {Chang, Jianming and Fang, Mingliang and Zalcman, Lawrence},
     title = {Normal families of holomorphic functions},
     journal = {Illinois J. Math.},
     volume = {48},
     number = {3},
     year = {2004},
     pages = { 319-337},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1258136186}
}
Chang, Jianming; Fang, Mingliang; Zalcman, Lawrence. Normal families of holomorphic functions. Illinois J. Math., Tome 48 (2004) no. 3, pp.  319-337. http://gdmltest.u-ga.fr/item/1258136186/