A Defeasible Logic Reasoner for the Semantic Web

N. Bassiliades, G. Antoniou, I. Vlahavas, “A Defeasible Logic Reasoner for the Semantic Web”, Third International Workshop on Rules and Rule Markup Languages for the Semantic Web (RuleML 2004), G. Antoniou, H. Boley (Ed.), Springer-Verlag, LNCS 3323, pp. 49-64, Hiroshima, Japan, 8 Nov. 2004, 2004.

RDF, rules, reasoning, defeasible logic, rule markup languages, semantic brokering.

Defeasible reasoning is a rule-based approach for efficient reasoning with incomplete and inconsistent information. Such reasoning is, among others, useful for ontology integration, where conflicting information arises naturally; and for the modeling of business rules and policies, where rules with exceptions are often used. This paper describes these scenarios in more detail, and reports on the implementation of a system for defeasible reasoning on the Web. The system is called DR-DEVICE and is capable of reasoning about RDF metadata over multiple Web sources using defeasible logic rules. The system is imple-mented on top of CLIPS production rule system and builds upon R-DEVICE, an earlier deductive rule system over RDF metadata that also supports derived attribute and aggregate attribute rules. Rules can be expressed either in a native CLIPS-like language, or in an extension of the OO-RuleML syntax. The opera-tional semantics of defeasible logic are implemented through compilation into the generic rule language of R-DEVICE. The paper includes a complete exam-ple of a semantic web broker that reasons about apartment renting.