Differential inequalities and quasi-normal families

Roi Bar, Jürgen Grahl, Shahar Nevo

We show that a family $\mathcal{F}$ of meromorphic functions in a domain $D$ satisfying $$\frac{|f^{(k)}|}{1+|f^{(j)}|^α}(z)\ge C \qquad \mbox{for all} z\in D \mbox{and all} f\in {\ca…