Adding Constraints to OWL, Boris Motik University Of Manchester
Compares database constraint definition with OWL as in lots of cases we want to use owl like db constraints, rather than solely for inferencing.
Interesting idea as OWL provides a very rich schema definition language such as hierarchies/memberships/restrictions etc.
Proposes a notion of extended OWL Knowledge bases where the TBox is compartmentalized into Schema and Constraints, constraints operating under a closed world type assumption, where the absence of a fact from the KB means an invalidated constraint.
This is an something we’ve explored a little, although on a much simpler level using RDFS and OWL constructs alongside schema annotations to describe constraints on classes and datatype properties. What we were aiming for was to enable some basic constraints to be derived from any existing RDFS schema, but to also allow schema to be annotated with additional constraints where required. We characterised our solution as Closed World Consistency Checking, and basically it consists of a vocabulary for annotating the RDFS schema with simple constraint definitions, plus some simple code to validate RDF instance data according to the annotated constraints and some others implied by existing RDFS/OWL constructs (like cardinality etc). The implementation of this is conceptually quite similar to the divided TBox approach.
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