What are the plans for OWL 2 support? How difficult is it to have a configurable option that turns off the open world assumption. No flames, please. There are products that do this and claim superior performance.
On Mar 24, 2013, at 3:00 PM, Dave Reynolds wrote: > On 24/03/13 17:27, Joshua TAYLOR wrote: >> On Sat, Mar 23, 2013 at 11:41 AM, Luis Eufrasio Teixeira Neto >> <[email protected]> wrote: >>> does anybody could send me an example of an ontology having a max >>> cardinality restriction over an objecct property and a sample jena code for >>> readind the value of the max cardinality, please? >> >> MaxCardinality Restrictions are an OWL2 feature, and Jena's OntModels >> don't support OWL2, > > maxCardinality is OWL1 and supported by OntModels. > > maxQualifiedCardinality is indeed OWL2 and not supported other than by > manually creating/parsing at the RDF level, as you say. > > Dave > > >> so you can't use the OntModel methods (that would >> otherwise do exactly what you want): >> >> >> import com.hp.hpl.jena.ontology.OntClass; >> import com.hp.hpl.jena.ontology.OntModel; >> import com.hp.hpl.jena.ontology.OntModelSpec; >> import com.hp.hpl.jena.ontology.OntProperty; >> import com.hp.hpl.jena.ontology.ProfileException; >> import com.hp.hpl.jena.rdf.model.ModelFactory; >> >> public class MaxCardinality { >> public static void main(String[] args) { >> // Create an Ont Model >> String ns = "http://www.example.com/ontology#";; >> OntModel model = ModelFactory.createOntologyModel( >> OntModelSpec.OWL_DL_MEM ); >> // Assert that a game has at most 4 players >> OntClass game = model.createClass( ns+"Game" ); >> OntClass player = model.createClass( ns+"Player" ); >> OntProperty hasPlayer = model.createOntProperty( ns+"hasPlayer" >> ); >> OntClass restriction; >> try { >> restriction = model.createMaxCardinalityQRestriction( >> null, >> hasPlayer, 4, player ); >> } >> catch ( ProfileException e ) { >> System.err.println( "Couldn't create the restriction." >> ); >> e.printStackTrace(); >> return; >> } >> game.addSuperClass( restriction ); >> model.write( System.out, "RDF-XML/ABBREV" ); >> } >> } >> >> >> If you try that code, you'll get the output: >> >> >> Couldn't create the restriction. >> com.hp.hpl.jena.ontology.ProfileException: Attempted to use language >> construct MAX_CARDINALITY_Q that is not supported in the current >> language profile: OWL DL >> at >> com.hp.hpl.jena.ontology.impl.OntModelImpl.checkProfileEntry(OntModelImpl.java:3044) >> at >> com.hp.hpl.jena.ontology.impl.OntModelImpl.createMaxCardinalityQRestriction(OntModelImpl.java:1748) >> at MaxCardinality.main(MaxCardinality.java:19) >> >> >> However, if you've already got the ontology that you need in RDF/XML, >> and can load it into Jena, you can get the restriction object from the >> serialization. (However, given that OWL can be encoded into RDF in >> various ways, this might not work in all cases). Here's code that >> does just that. (The output includes a serialization of the model, so >> you can see what the data looked like: >> >> >> import com.hp.hpl.jena.ontology.OntModel; >> import com.hp.hpl.jena.ontology.Restriction; >> import com.hp.hpl.jena.rdf.model.ModelFactory; >> import com.hp.hpl.jena.rdf.model.ResIterator; >> import com.hp.hpl.jena.vocabulary.OWL2; >> >> public class ReadMaxCardinality { >> public static void main(String[] args) { >> // Create an OntModel, read the contents in from disk, and >> write the >> // contents so that everyone can see. >> OntModel model = ModelFactory.createOntologyModel(); >> model.read( >> "file:///home/taylorj/Documents/ontologies/ontology/ontology.owl" >> ); >> model.write( System.out, "RDF/XML-ABBREV" ); >> >> // You'll need to find some way to identify the max cardinality >> restrictions. I'm assuming that >> // every max cardinality restriction will have a value for >> OWL2.maxQualifiedCardinality, and that >> // *only* max cardinality restrictions will have a value for >> that peoperty. >> for ( ResIterator it = model.listSubjectsWithProperty( >> OWL2.maxQualifiedCardinality ); it.hasNext() ; ) { >> // Making r a restriction lets us use >> Restriction#getOnProperty as >> in (i), but >> // we could also just make r a resource and use >> Resource#getPropertyValue(), >> // as in (2,3,4). >> Restriction r = it.next().as( Restriction.class ); >> System.out.println( "(1) on property: " + >> r.getOnProperty() ); >> System.out.println( "(2) on property: " + >> r.getPropertyValue( >> OWL2.onProperty )); >> System.out.println( "(3) on class: " + >> r.getPropertyValue( >> OWL2.onClass )); >> System.out.println( "(4) max cardinality: " + >> r.getPropertyValue( >> OWL2.maxQualifiedCardinality )); >> } >> } >> } >> >> >> <rdf:RDF >> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"; >> xmlns:owl="http://www.w3.org/2002/07/owl#"; >> xmlns:xsd="http://www.w3.org/2001/XMLSchema#"; >> xmlns="http://www.example.com/ontology#"; >> xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#";> >> <owl:Ontology rdf:about="http://www.example.com/ontology"/> >> <owl:Class rdf:about="http://www.example.com/ontology#Game";> >> <rdfs:subClassOf> >> <owl:Restriction> >> <owl:maxQualifiedCardinality >> rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger"; >> >4</owl:maxQualifiedCardinality> >> <owl:onClass> >> <owl:Class rdf:about="http://www.example.com/ontology#Player"/> >> </owl:onClass> >> <owl:onProperty> >> <owl:ObjectProperty >> rdf:about="http://www.example.com/ontology#hasPlayer"/> >> </owl:onProperty> >> </owl:Restriction> >> </rdfs:subClassOf> >> </owl:Class> >> </rdf:RDF> >> (1) on property: http://www.example.com/ontology#hasPlayer >> (2) on property: http://www.example.com/ontology#hasPlayer >> (3) on class: http://www.example.com/ontology#Player >> (4) max cardinality: 4^^http://www.w3.org/2001/XMLSchema#nonNegativeInteger >> >> >> Hope this helps! >> //JT >> >
