Deciding Query Entailment in Fuzzy OWL Lite Ontologies

Significant research efforts in the Semantic Web community are recently directed toward the representation and reasoning with fuzzy ontologies. Description logics (DLs) are the logical foundations of standard Web ontology languages. Conjunctive queries are deemed as an expressive reasoning service for DLs. This chapter focuses on fuzzy (threshold) conjunctive queries over knowledge bases encoding in fuzzy DL , the logic counterpart of fuzzy OWL Lite language. It shows decidability of fuzzy query entailment in this setting by providing a corresponding tableau-based algorithm. The chapter shows data complexity for answering fuzzy conjunctive queries in fuzzy is in coNP, as long as only simple roles occur in the query. Regarding combined complexity, this research proves a co3NExpTime upper bound in the size of the knowledge base and the query.