Monoids over domains

In this paper, we describe three distinct monoids over domains, each with a commutative analog, which define bag domain monoids. Our results were inspired by work by Varacca (Varacca 2003), and they lead to a constructive approach to his Hoare indexed valuations over a continuous poset P. We use our constructive approach to describe an analog of the probabilistic power domain, and the laws that characterise it, that forms a Scott-closed subset of Varacca's construct. We call these the Hoare random variables over P.