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Volume 35 • Number 2 • 2012 |
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Normality Criteria for Families of Meromorphic Function Concerning Shared Values
Jianming Qi, Jie Ding and Lianzhong Yang
Abstract.
Let $k$ be a positive integer and let $\mathcal{F}$ be a family of meromorphic functions in the plane domain $D$ all of whose zeros with multiplicity at least $k$. Let $P=a_pz^p+\cdots+a_2z^2+z$ be a polynomial, $a_p,a_2\neq0$ and $p=\deg(P)\geq k+2$. If, for each $f,g\in \mathcal{F}$, $P(f)G(f)$ and $P(g)G(g)$ share a non-zero constant $b$ in $D$, where $G(f)=f^{(k)}+H(f)$ be a differential polynomial of $f$ satisfying $\frac{w}{\deg}|_H\leq \frac{k}{l+1}+1$ or $w(H)-\deg(H)<k$, then $\mathcal{F}$ is normal in $D$.
2010 Mathematics Subject Classification: 30D35, 30D45.
Full text: PDF
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