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Pellet

See also OWL, Jena.
  1. Pellet/OWL Tutorial
  2. Pellet/OWL Tutorial (2)

No query handler found for rdf:type

I was getting the following warning messages in the console:

3281 [main] DEBUG com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph  - Adding rule [ (?a rdf:type http://openiaml.org/model0.2#CompositeCondition) -> (?a rdf:type 'min(http://openiaml.org/model0.2#conditions '0'^^http://www.w3.org/2001/XMLSchema#int)'^^urn:x-hp-jena:Functor) ]
31/08/2009 22:09:56 org.mindswap.pellet.jena.graph.query.GraphQueryHandler findTriple
WARNING: No query handler found for http://www.w3.org/2000/01/rdf-schema#subClassOf http://www.w3.org/1999/02/22-rdf-syntax-ns#type http://www.w3.org/1999/02/22-rdf-syntax-ns#Property
31/08/2009 22:09:56 org.mindswap.pellet.jena.graph.query.GraphQueryHandler findTriple
WARNING: No query handler found for http://www.w3.org/2000/01/rdf-schema#subClassOf http://www.w3.org/1999/02/22-rdf-syntax-ns#type http://www.w3.org/1999/02/22-rdf-syntax-ns#Property
31/08/2009 22:09:56 org.mindswap.pellet.jena.graph.query.GraphQueryHandler findTriple
WARNING: No query handler found for http://www.w3.org/2002/07/owl#equivalentClass http://www.w3.org/1999/02/22-rdf-syntax-ns#type http://www.w3.org/1999/02/22-rdf-syntax-ns#Property

The code that I was using to execute my Pellet/Jena reasoner was the following:

IFile f = project.getFile("input.owl");
OntModel model = ModelFactory.createOntologyModel( PelletReasonerFactory.THE_SPEC );
model.read(f.getContents(), "http://openiaml.org/test");

Reasoner reasoner = ReasonerRegistry.getOWLReasoner();
reasoner.setParameter(ReasonerVocabulary.PROPtraceOn, true);
reasoner = reasoner.bindSchema(schema); // would warn here

Following inspiration from this mailing list post, I changed it from the OWLReasoner to the PelletReasoner, which resolved this warning completely:

IFile f = project.getFile("input.owl");
OntModel model = ModelFactory.createOntologyModel( PelletReasonerFactory.THE_SPEC );
model.read(f.getContents(), "http://openiaml.org/test");

Reasoner reasoner = new PelletReasoner(); // no more problems
reasoner.setParameter(ReasonerVocabulary.PROPtraceOn, true);
reasoner = reasoner.bindSchema(schema);

Upon further investigation, it seems these errors were being caused by the Reasoner.bindSchema() method. Perhaps these errors indicate that the current model cannot support some of the predicates asserted - e.g. Jena can't support OWL 2, unless the following @include is used:

@include <OWL>.

Categories: Java | Semantic Web | Reasoners | Logic | OWL
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Last edited by jevon jevon 97 months ago