English

Differential inequalities and quasi-normal families

Complex Variables 2016-09-29 v2

Abstract

We show that a family F{\cal F} of meromorphic functions in a domain DD satisfying f(k)1+f(j)α(z)C\mboxforallzD\mboxandallfF\frac{|f^{(k)}|}{1+|f^{(j)}|^\alpha}(z)\ge C \qquad \mbox{for all} z\in D \mbox{and all} f\in {\cal F} (where kk and jj are integers with k>j0k>j\ge 0 and C>0C>0, α>1\alpha>1 are real numbers) is quasi-normal. Furthermore, if all functions in F{\cal F} are holomorphic, the order of quasi-normality of F{\cal F} is at most j1j-1. The proof relies on the Zalcman rescaling method and previous results on differential inequalities constituting normality.

Keywords

Cite

@article{arxiv.1310.3635,
  title  = {Differential inequalities and quasi-normal families},
  author = {Roi Bar and Jürgen Grahl and Shahar Nevo},
  journal= {arXiv preprint arXiv:1310.3635},
  year   = {2016}
}