Query Answering for OWL-DL with rules

• Published in: Web semantics Vol. 3; no. 1; pp. 41 - 60
• Main Authors: Motik, Boris, Sattler, Ulrike, Studer, Rudi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2005
• Subjects: Decidability; Description logics; Hybrid languages; Rules; Hybrid languages; Decidability; Description logics; Rules
• ISSN: 1570-8268; 1873-7749
• DOI: 10.1016/j.websem.2005.05.001

Both OWL-DL and function-free Horn rules are decidable fragments of first-order logic with interesting, yet orthogonal expressive power. A combination of OWL-DL and rules is desirable for the Semantic Web; however, it might easily lead to the undecidability of interesting reasoning problems. Here, we present a
decidable such combination where rules are required to be
DL-
safe: each variable in the rule is required to occur in a non-DL-atom in the rule body. We discuss the expressive power of such a combination and present an algorithm for query answering in the related logic
S
H
I
Q
extended with DL-safe rules, based on a reduction to disjunctive programs.