document: A proposal for an owl rules language Although the OWLWeb Ontology Language adds considerable expressive power to the Semantic Web it does have expressive limitations , particularly with respect to what can be said about properties . Wepresent ORL ( OWL Rules Language ) , a Horn clause rules extension to OWL that overcomes many of these limitations . ORL extends OWL in a syntactically and semantically coherent manner : the basic syntax for ORL rules is an extension of the abstract syntax for OWL DL and OWLLite ; ORL rules are given formal meaning via an extension of the OWLDL model-theoretic semantics ; ORL rules are given an XML syntax basedon the OWL XML presentation syntax ; and a mapping from ORL rules to RDF graphs is given based on the OWL RDF\/XML exchange syntax . Wediscuss the expressive power of ORL , showing that the ontology consistency problem is undecidable , provide several examples of ORLusage , and discuss how reasoning support for ORL might be provided .
doc_bio_tags: O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O