An upper bound for the least critical values of finite Blaschke products

Abstract

For the finite Blaschke products $B$ of degree $n\geqslant2$ such that $B(0)=0$ and $ B'(0)\ne0$, the supremum of the minimum moduli of their critical values is found which depends only on $n$ and $|B'(0)|$. Bibliography: 12 titles.