Commuting rational functions revisited

Abstract: Let $B$ be a rational function of degree at least two that is neither a Latt`es map nor conjugate to $z^{\pm n}$ or $\pm T_n$. We provide a method for describing the set $C_B$ consisting of all rational functions commuting with $B.$ Specifically, we define an equivalence relation $\underset{B}{\sim}$ on $ C_B$ such that the quotient $ C_B/\underset{B}{\sim}$ possesses the structure of a finite group $G_B$, and describe generators of $G_B$ in terms of the fundamental group of a special graph associated with $B$.