Compositional Semantics for Description Knowledge Bases with Rules

Descriptions and Rules are diierent, complementary, essential forms of knowledge. Descriptions are analytic and closed; rules are contingent and open. The two forms can be integrated either by compiling one form within the other, or by constructing a hybrid framework. The hybrid solution keeps the modular independent status of each approach, but needs an underlying integration framework, in which a coherent compositional semantics can be deened. In this paper we introduce an architecture for a hybrid knowledge base that integrates descriptions with expressive object-oriented rules. The knowledge base manages a database of explicit descriptions and facts, by consulting two separate reasoners: DL { The Description Languages reasoner, and R { The Rules reasoner. The architecture generalizes all existing hybrids of descriptions and rules. Its declarative semantics relies on F-Logic as an underlying semantics, and is consistent with the (sometimes only operational) semantics of existing hybrids. The contribution of this paper is in building compositional semantics, given as a collection of syntactic objects, for hybrid description knowledge bases. The compositional semantics conceives the role of a description knowledge base as a computational task, i.e., computing descriptions and predications (or rules). It respects the modularity of its components, allows them to operate under diierent semantical policies, and its variants enjoy diierent degrees of description-orientedness and openness.