English

Normality through sharing of pairs of functions with derivatives

Complex Variables 2024-11-11 v1

Abstract

Let FM(D)\mathcal{F}\subset\mathcal{M}(D) and let a,ba, b and cc be three distinct complex numbers. If, there exist a holomorphic function hh on DD and a positive constant ρ\rho such that for each fF,f\in\mathcal{F}, ff and ff^{'} partially share three pairs of functions (a,h), (b,cf)(a,h), \ (b, c_f) and (c,df)(c,d_f) on D,D, where cfc_f and dfd_f are some values in some punctured disk Dρ(0),D^*_{\rho}(0), then F\mathcal{F} is normal in DD. This is an improvement of Schwick's result[Arch. Math. (Basel), \textbf{59} (1992), 50-54]. We also obtain several normality criteria which significantly improve the existing results and examples are given to establish the sharpness of results.

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Cite

@article{arxiv.2209.04314,
  title  = {Normality through sharing of pairs of functions with derivatives},
  author = {Kuldeep Singh Charak and Manish Kumar and Anil Singh},
  journal= {arXiv preprint arXiv:2209.04314},
  year   = {2024}
}

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10 pages