Normal cyclotomic schemes over a finite commutative ring

Cyclotomic association schemes over a finite commutative ring $R$ with identity are studied. The main goal is to identify the normal cyclotomic schemes $\mathcal{C}$, i.e., those for which $\operatorname{Aut}(\mathcal{C})\le A\Gamma L_1(R)$. The problem reduces to the case where the ring $R$ is local, and in this case a necessary condition of normality in terms of the subgroup of $R^\times$ that determines $\mathcal{C}$ is given. This condition is proved to be sufficient for a large class of local rings including the Galois rings of odd characteristic.