Semigroups of I-type

Tatiana Gateva-Ivanova, Michel Van den Bergh

Assume that $S$ is a semigroup generated by $\{x_1,...,x_n\}$, and let $\Uscr$ be the multiplicative free commutative semigroup generated by $\{u_1,...,u_n\}$. We say that $S$ is o…