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On the value distribution of a Differential Monomial and some normality criteria

Complex Variables 2020-08-31 v2

Abstract

Let ff be a transcendental meromorphic function defined in the complex plane C\mathbb{C}, and φ(≢0,)\varphi(\not\equiv 0,\infty) be a small function of ff. In this paper, We give a quantitative estimation of the characteristic function T(r,f)T(r, f) in terms of N(r,1M[f]φ(z))N\left(r,\frac{1}{M[f]-\varphi(z)}\right) as well as \olN(r,1M[f]φ(z))\ol{N}\left(r,\frac{1}{M[f]-\varphi(z)}\right), where M[f]M[f] is the differential monomial, generated by ff.\par Moreover, we prove one normality criterion: Let F\mathscr{F} be a family of analytic functions on a domain DD and let k(1)k(\geq1), q0(3)q_{0}(\geq 3), qi(0)q_{i}(\geq0) (i=1,2,,k1)(i=1,2,\ldots,k-1), qk(1)q_{k}(\geq1) be positive integers. If for each fFf\in \mathscr{F}, ff has only zeros of multiplicity at least kk, and fq0(f)q1...(f(k))qk1f^{q_{0}}(f')^{q_{1}}...(f^{(k)})^{q_{k}}\not=1, then F\mathscr{F} is normal on domain DD.

Keywords

Cite

@article{arxiv.1903.10940,
  title  = {On the value distribution of a Differential Monomial and some normality criteria},
  author = {Weiran Lü and Bikash Chakraborty},
  journal= {arXiv preprint arXiv:1903.10940},
  year   = {2020}
}

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8 pages