WSML Deliverable D 20 . 1 v 0 . 2 OWL −

This deliverable presents restricted variants of the OWL Lite, DL and Full species of the OWL ontology language, called OWL Lite−, OWL DL− and OWL Full−, respectively. OWL Lite− and OWL DL− are strict subsets of OWL Lite and OWL DL. They are limited in such a way that there exists a translation from both languages directly into the deductive database language Datalog. Thus, any OWL Lite− or OWL DL− ontology can be translated into Datalog. An ontology language for which a translation to Datalog exists has several advantages. Most notably, it can benefit from highly optimized query answering engines, and allows for easy implementation of a rule and a query language on top of the ontology. It turns out that most current ontologies fall inside the fragments defined by OWL Lite− or OWL DL−. In addition, we introduce a datatype extension of OWL Lite− (and thus OWL DL−) based on the datatype groups approach of OWL-E. We describe the restrictions on the OWL Lite abstract syntax and provide an analysis of the features of OWL Lite, which are not included in OWL Lite−, and give a rationale for not including them in the language. We present the RDF syntax and the model-theoretic semantics for OWL Lite−, introduce the datatype extension of OWL Lite− and relate OWL Lite− with RDFS. We then present the extensions of OWL Lite− in order to create OWL DL−, together with its abstract syntax and model-theoretic semantics. Finally, we describe an F-Logic based extension of OWL DL− to create OWL Full− and a new RDFS semantics which offers a proper layering of OWL Full− on top of RDFS. Copyright c © 2004 DERI R © , All Rights Reserved. DERI liability, trademark, document use, and software licensing rules apply.