
doi: 10.1007/bf03321002
Under review the author proves the following ``Picard type'' theorem and a corresponding normality criterion: (1) Let \(f\) be an entire function, \(n\geq 2\), \(k\geq 1\) and \(a,a_1,\dots, a_m\in\mathbb{C}\) with \(a\neq 0\) and let \[ P[u]:= \sum^m_{j=1}a_j \prod^{s_j}_{\nu=1} u^{(k_\nu^{(j)})} \] be a differential polynomial with \(2\leq s_j\leq n-1\), \(\sum^{s_j}_{\nu=1} (k_\nu^{(j)}) \geq 1\) for \(j=1,2,\dots,m\). If \(\psi:=f^n+ af^{(1)}+ P[f]\) has no zeros in \(\mathbb{C}\), then \(f\) is constant. (2) Let \({\mathcal F}\) be a family of functions analytic in \(\mathbb{D}\), \(n\geq 2\), \(k\geq 1\) and let \(a,b,a_1,\dots,a_m\) be meromorphic in \(\mathbb{D}\) with \(a\neq 0\), where all poles of \(a\) have multiplicity at most \(n-1\). Let \(P[u]\) be the differential polynomial of (1) with \[ (n-1) \sum^{s_j}_{\nu=1} k_\nu^{(j)}+ k s_j\leq kn \] for all \(j=1,2,\dots,m\) where equality can hold only if \(2\leq s_j\leq n-1\). If for all \(f\in{\mathcal F}\) and for all \(z\in\mathbb{D}\) we have \[ a(z)f^n(z)+ f^{(k)}(z)+ P[f](z) -b(z)\neq 0, \] then \({\mathcal F}\) is normal. These results generalize results of Hayman, Drasin, Langley, Chen and Hua.
differential polynomial, normality, Bloch's principal, Normal functions of one complex variable, normal families, value distribution, Value distribution of meromorphic functions of one complex variable, Nevanlinna theory
differential polynomial, normality, Bloch's principal, Normal functions of one complex variable, normal families, value distribution, Value distribution of meromorphic functions of one complex variable, Nevanlinna theory
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 2 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
