Ideal factoriality, semistar operations, and quasiprincipal Ideals

The w-operation, a "smoother" variant of the classic t-operation on the set of ideals of a commutative ring R, has recently attracted significant attention. We study when R's monoid of w-ideals is "factorial" in some sense. For example, we show that every proper w-ideal of R has a unique up to order irredundant w-factorization into w-unfactorable w-ideals if and only if R is a finite direct product of Krull domains and principal ideal rings, if and only if every w-ideal is w-quasiprincipal. We prove several analogous results regarding other kinds of "w-ideal factoriality" and generalize these results via semistar operations.