A Semantic Foundation for Trust Management Languages with Weights: An Application to the RTFamily

In this paper, we present a variant of Datalog language (we call it Datalog W ) able to deal with weights on ground facts and to consequently compute a feedback result for the goal satisfaction. The weights are chosen from a proper c-semiring. In our context, our goal is to use this language as a semantic foundation for languages for expressing trust relationships. As a matter of fact, many of them have a semantics given in terms of crisp constraints: our approach is to extend them to cover also the soft case. Thus, we apply Datalog W as the basis to give a uniform semantics to declarative RT W (Trust Management) language family. The approach is rather generic and could be applied to other trust management languages based on Datalog, as a semantic sublayer to represent trust management languages where the trust level is relevant.