Cohn's theorem

Cohn's theorem is a result in the field of algebra, particularly concerning the representation of semigroups and rings. The theorem primarily addresses the structure of commutative semigroups and explores conditions under which a commutative semigroup can be embedded into a given algebraic structure. In more specific terms, Cohn's theorem states that every commutative semigroup can be represented as a certain kind of matrix semigroup over a certain commutative ring.