[Pellet-users] Working on a copy of an OntModel raises an InternalReasonerException

[Franz Schenk]

Hi,

i created a copy of an OntModel (which was in turn created using  Pellet
as a reasoning engine), see the java-code below for details.

However, working with that copy (esp. iterating over instances and their
properties) reveals an unexpected (at least unexpected to me) behaviour.

(The interested reader will find the error message below the program
code at the end of this message.)

Note that the error disappears when the copy of the pellet-model is
created using any different OntModelSpec.

What I'd like to ask here is whether there is anything obvious going
wrong with either my approach or the behaviour of the reasoning engine?

Best regards,
Franz




import org.mindswap.pellet.jena.PelletReasonerFactory;
import com.hp.hpl.jena.ontology.Individual;
import com.hp.hpl.jena.ontology.OntClass;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Statement;
import com.hp.hpl.jena.rdf.model.StmtIterator;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;

public class TestOntModelCopy {
public static void main(String[] args){

Model model = ModelFactory.createDefaultModel();
model.read("http://user.informatik.uni-goettingen.de/~schenk/data/family_ont.n3","N3");

OntModel pelletmodel = ModelFactory.
createOntologyModel(PelletReasonerFactory.THE_SPEC);

pelletmodel.add(model);

OntModel copyModel =
ModelFactory.createOntologyModel(PelletReasonerFactory.THE_SPEC);

//OntModel copyModel =
// ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);
		
copyModel.add(pelletmodel);
OntClass owlThing =
copyModel.getOntClass("http://www.w3.org/2002/07/owl#Thing");
		
ExtendedIterator instanceIter = owlThing.listInstances();
while (instanceIter.hasNext()) {
	Object ind_obj = instanceIter.next();
	if (ind_obj instanceof Individual ) {
		Individual individual = (Individual) ind_obj;
		StmtIterator propertyiter2 =
	 		individual.listProperties();
		while (propertyiter2.hasNext()) {
			Statement statement =
				propertyiter2.nextStatement();
			System.out.println(statement.toString());
		}
		propertyiter2.close();
	}
}
instanceIter.close();
}
}



========================================================================================

Exception in thread "main"
org.mindswap.pellet.exceptions.InternalReasonerException: Trying to
remove a non-existing edge [http://foo.org/dummy#Deby,
http://foo.org/dummy#hasAncestor, http://foo.org/dummy#Charlene] - [0-{0}]
	at org.mindswap.pellet.Node.removeInEdge(Node.java:291)
	at org.mindswap.pellet.Individual.prune(Individual.java:1068)
	at
org.mindswap.pellet.CompletionStrategy.mergeIndividuals(CompletionStrategy.java:2144)
	at
org.mindswap.pellet.CompletionStrategy.mergeTo(CompletionStrategy.java:2064)
	at
org.mindswap.pellet.CompletionStrategy.applyNominalRule(CompletionStrategy.java:1983)
	at
org.mindswap.pellet.CompletionStrategy.applyNominalRule(CompletionStrategy.java:1896)
	at
org.mindswap.pellet.CompletionStrategy.applyNominalRule(CompletionStrategy.java:1867)
	at org.mindswap.pellet.SROIQStrategy.complete(SROIQStrategy.java:150)
	at org.mindswap.pellet.ABox.isConsistent(ABox.java:1605)
	at org.mindswap.pellet.ABox.isType(ABox.java:1088)
	at org.mindswap.pellet.KnowledgeBase.retrieve(KnowledgeBase.java:3395)
	at org.mindswap.pellet.KnowledgeBase.getInstances(KnowledgeBase.java:2681)
	at org.mindswap.pellet.KnowledgeBase.getDifferents(KnowledgeBase.java:2395)
	at
org.mindswap.pellet.jena.PelletInfGraph.differentFromIterator(PelletInfGraph.java:1022)
	at
org.mindswap.pellet.jena.PelletInfGraph.findInABox(PelletInfGraph.java:375)
	at
org.mindswap.pellet.jena.PelletInfGraph.findWithContinuation(PelletInfGraph.java:212)
	at
com.hp.hpl.jena.reasoner.BaseInfGraph.graphBaseFind(BaseInfGraph.java:345)
	at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:257)
	at
com.hp.hpl.jena.rdf.model.impl.ModelCom.listStatements(ModelCom.java:385)
	at
com.hp.hpl.jena.rdf.model.impl.ModelCom.listStatements(ModelCom.java:390)
	at
com.hp.hpl.jena.rdf.model.impl.ResourceImpl.listProperties(ResourceImpl.java:152)
	at
org.semwebtech.dlflorid.test.TestOntModelCopy.main(TestOntModelCopy.java:34)