Explanations for Inconsistent Ontologies with OWL API 5.1.14

[mthl]

Hello,

I am trying to use this package for checking inconsistencies in an OWL 2 DL ontology. I am using OWL API 5.1.14 and owlexplanation 5.0.0 but I am failing to adapt an old example found on stackoverflow to OWL API v5.

Any help would be welcome.

[ignazio1977]

This version compiles on owlexplanation version 5:

OWLOntology ont = OWLManager.createOWLOntologyManager().createOntology();
OWLOntologyManager m = ont.getOWLOntologyManager();
OWLDataFactory df = m.getOWLDataFactory();
OWLClass class1 = df.getOWLClass(IRI.create("urn:test:class1"));
OWLClass class2 = df.getOWLClass(IRI.create("urn:test:class2"));
OWLIndividual i = df.getOWLNamedIndividual(IRI.create("urn:test:i"));
// create an inconsistent ontology by declaring an individual member of two disjoint classes
m.addAxiom(ont, df.getOWLDisjointClassesAxiom(class1, class2));
m.addAxiom(ont, df.getOWLClassAssertionAxiom(class1, i));
m.addAxiom(ont, df.getOWLClassAssertionAxiom(class2, i));
// create the explanation generator
ExplanationGenerator<OWLAxiom> explainInconsistency = new InconsistentOntologyExplanationGeneratorFactory(rf, 
// these are the two arguments needed - a data factory and a supplier of ontology managers.
    OWLManager.getOWLDataFactory(), ()->OWLManager.createOWLOntologyManager(),
    1000L).createExplanationGenerator(ont);
// Ask for an explanation of `Thing subclass of Nothing` - this axiom is entailed in any inconsistent ontology
Set<Explanation<OWLAxiom>> explanations = explainInconsistency.getExplanations(df.getOWLSubClassOfAxiom(df
    .getOWLThing(), df.getOWLNothing()));

[mthl]

Thanks for your quick reply,

I have indeed something that is compiling but failing at runtime with an Illegal state exception.

Exception in thread "main" java.lang.IllegalStateException: value cannot be null at this stage
	at org.semanticweb.owlapi.util.OWLAPIPreconditions.verifyNotNull(OWLAPIPreconditions.java:56)
	at org.semanticweb.owlapi.util.OWLAPIPreconditions.verifyNotNull(OWLAPIPreconditions.java:40)
	at uk.ac.manchester.cs.owl.explanation.ordering.ExplanationOrdererImplNoManager$SeedExtractor.getTarget(ExplanationOrdererImplNoManager.java:311)
	at uk.ac.manchester.cs.owl.explanation.ordering.ExplanationOrdererImplNoManager.getOrderedExplanation(ExplanationOrdererImplNoManager.java:174)
	at org.semanticweb.owl.explanation.api.Explanation.toString(Explanation.java:149)
	at java.base/java.lang.String.valueOf(String.java:2951)
	at java.base/java.io.PrintStream.println(PrintStream.java:897)
	at java.base/java.lang.Iterable.forEach(Iterable.java:75)
	at org.w3id.Http.main(Http.java:41)

Here is the code I am running

package org.w3id;

import java.util.Set;

import org.semanticweb.HermiT.ReasonerFactory;
import org.semanticweb.owl.explanation.api.Explanation;
import org.semanticweb.owl.explanation.api.ExplanationGenerator;
import org.semanticweb.owl.explanation.impl.blackbox.checker.InconsistentOntologyExplanationGeneratorFactory;
import org.semanticweb.owlapi.apibinding.OWLManager;
import org.semanticweb.owlapi.model.IRI;
import org.semanticweb.owlapi.model.OWLAxiom;
import org.semanticweb.owlapi.model.OWLClass;
import org.semanticweb.owlapi.model.OWLDataFactory;
import org.semanticweb.owlapi.model.OWLIndividual;
import org.semanticweb.owlapi.model.OWLOntology;
import org.semanticweb.owlapi.model.OWLOntologyManager;

public class Http {
    public static void main(String[] args) throws Exception {
        OWLOntology ont = OWLManager.createOWLOntologyManager().createOntology();
        OWLOntologyManager m = ont.getOWLOntologyManager();
        OWLDataFactory df = m.getOWLDataFactory();
        OWLClass class1 = df.getOWLClass(IRI.create("urn:test:class1"));
        OWLClass class2 = df.getOWLClass(IRI.create("urn:test:class2"));
        OWLIndividual i = df.getOWLNamedIndividual(IRI.create("urn:test:i"));
        // create an inconsistent ontology by declaring an individual member of two disjoint classes
        m.addAxiom(ont, df.getOWLDisjointClassesAxiom(class1, class2));
        m.addAxiom(ont, df.getOWLClassAssertionAxiom(class1, i));
        m.addAxiom(ont, df.getOWLClassAssertionAxiom(class2, i));
        ReasonerFactory rf = new ReasonerFactory();
        // create the explanation generator
        ExplanationGenerator<OWLAxiom> explainInconsistency =
                new InconsistentOntologyExplanationGeneratorFactory(rf,
                        OWLManager.getOWLDataFactory(),
                        OWLManager::createOWLOntologyManager,
                        1000L).createExplanationGenerator(ont);
        // Ask for an explanation of `Thing subclass of Nothing` - this axiom is entailed in any inconsistent ontology
        Set<Explanation<OWLAxiom>> explanations = explainInconsistency.getExplanations(
                df.getOWLSubClassOfAxiom(df.getOWLThing(), df.getOWLNothing()));
        explanations.forEach(System.out::println);
    }
}

My dependency specification is the following

  <dependencies>
    <dependency>
      <groupId>net.sourceforge.owlapi</groupId>
      <artifactId>org.semanticweb.hermit</artifactId>
      <version>1.3.8.510</version>
    </dependency>
    <dependency>
      <groupId>net.sourceforge.owlapi</groupId>
      <artifactId>owlapi-distribution</artifactId>
      <version>5.1.14</version>
    </dependency>
    <dependency>
      <groupId>net.sourceforge.owlapi</groupId>
      <artifactId>owlexplanation</artifactId>
      <version>5.0.0</version>
    </dependency>
    <dependency>
      <groupId>net.sf.trove4j</groupId>
      <artifactId>core</artifactId>
      <version>3.1.0</version>
    </dependency>
  </dependencies>

trove4j seems to be implicitly required by HermiT.

[m0squito]

@mthl Were you able to make this work? I know it has been a while, but I got to the same "value cannot be null at this stage" exception with a very similar setup and code as yours.