Itô's theorem

Itô's theorem is a result in the mathematical discipline of representation theory due to Noboru Itô. It generalizes the well-known result that the dimension of an irreducible representation of a group must divide the order of that group.

Statement
Given an irreducible representation $V$ of a finite group $G$ and a maximal normal abelian subgroup $A ⊆ G$, the dimension of $V$ must divide $[G:A]$.