Towards a Nonmonotonic Extension to OWL
Yarden Katz, Bijan Parsia · 2005
Abstract. We discuss ALCK, a nonmontonic logic that augments ALC with the epistemic operator K, and argue that a similar extension to OWL would be desirable. We show, however, that at its current state the OWL syntax is too inflexible to capture even this syntactically simpleminded extension. Finally, we introduce our implementation of ALCK as an extension to the tableau-based OWL-DL reasoner Pellet. 1 Nonmonotonic logics, open and closed worlds Nonmonotonic logics were proven generally successful in capturing, among other things, several forms of common sense and database reasoning. A bold divide between the field of nonmonotonic formalisms and first-order reasoning (where description logics and OWL lie) rests in the closed v. open world assumption. In database systems, it is reasonable to assume that the data at hand is complete. Since no information outside the database is relevant, we say that our world is closed. Formally, if Σ �| = ϕ (where Σ is the knowledge in our database and ϕ is some formula), we assume ¬ϕ is the case. This constitutes the closed-world