Normal criteria of function families concerning shared values (Q410835)

Summary: We study the normality of families of meromorphic functions concerning shared values. We consider whether a family of meromorphic functions \(\mathcal F\) is normal in \(D\), if, for every pair of functions \(f\) and \(g\) in \(\mathcal F, f' - af^{-n}\) and \(g' - ag^{-n}\) share the value \(b\), where \(a\) and \(b\) are two finite complex numbers such that \(a \neq 0, n\) is a positive integer. Some examples show that the conditions in our results are best possible.