A commutative cancellative
idempotent-free semigroup (CCIF-) S can be described in terms of a commutative
cancellative semigroup C with identity, an ideal of C, and a function of C × C into
integers. If C is an abelian group, S has an archimedean component as an ideal; S
is called an N-semigroup. A CCIF-semigroup of finite rank has nontrivial
homomorphism into nonnegative real numbers.