Commutative Subring

Some articles on commutative subring:

Abelian Variety Of CM-type
... to have CM-type if it has a large enough commutative subring in its endomorphism ring End(A) ... the tensor product of End(A) with the rational number field Q, should contain a commutative subring of dimension 2d over Z ... The CM-type is a description of the action of a (maximal) commutative subring L of EndQ(A) on the holomorphic tangent space of A at the identity element ...