The ability to extract information from OWL ontologies is a basic requirement. While SPARQL and its extensions are being used as an OWL query language in many applications, their understanding of OWL’s semantics is at best incomplete. There is a pressing need for a concise, readable, and semantically robust query language for OWL. We describe a query language called SQWRL that we believe provides such a language. SQWRL is based on the SWRL rule language and uses SWRL’s strong semantic foundation as its formal underpinning. The resulting language provides a small but powerful array of operators that allows users to construct queries on OWL ontologies. SQWRL also contains novel set operators that can be used to perform closure operations to allow limited forms of negation as failure, counting, and aggregation.
