On a Type of Permutation Rational Functions over Finite Fields

Xiang-dong Hou, Christopher Sze

Let $p$ be a prime and $n$ be a positive integer. Let $f_b(X)=X+(X^p-X+b{)}^{-1}$, where $b\in {\mathbb{F}}_{p^n}$ is such that ${\text{Tr}}_{p^n/p}(b)\ne 0$. In 2008, Yuan et al. \cite{Yuan-…