# Fundamental normality test

Let ${\displaystyle {\mathcal {F}}}$ be a family of analytic functions defined on a domain ${\displaystyle \Omega }$. If there are two fixed complex numbers a and b that are omitted from the range of every ƒ ∈ ${\displaystyle {\mathcal {F}}}$, then ${\displaystyle {\mathcal {F}}}$ is a normal family on ${\displaystyle \Omega }$.