Class Semigroups of Integral Domains

This paper seeks ring-theoretic conditions of an integral domain R that reflect in the Clifford property or Boolean property of its class semigroup S(R), that is, the semigroup of the isomorphy classes of the nonzero (integral) ideals of R with the operation induced by multiplication. Precisely, in Section 3, we characterize integrally closed domains with Boolean class semigoup; in this case, S(R) identifies with the Boolean semigroup formed of all fractional overrings of R. In Section 4, we investigate Noetherian-like settings where the Clifford and Boolean properties of S(R) coincide with (Lipman and Sally-Vasconcelos) stability conditions; a main feature is that the Clifford property forces t−locally Noetherian domains to be one-dimensional Noetherian domains. Section 5 studies the transfer of the Clifford and Boolean properties to various pullback constructions. Our results lead to new families of integral domains with Clifford or Boolean class semigroup, moving therefore beyond the contexts of integrally closed domains or Noetherian domains. 1I would like to thank Benedict H. Gross for helpful discussions. Research supported by the Arab Fund for Economic and Social Development. Permanent address: Department of Mathematics, P.O. Box 5046, KFUPM, Dhahran 31261, Saudi Arabia.