Get OWL characters with the same object properties using OWL API 4.0
I am using OWL Api 4.0 in eclipse 3.4 with simple ontology in Protege 4. I have two classes "Ward" and "Gaurdian". The faces of these classes are linked by the isWardOf object property. How can I get Ward people who are related to the same Gaurdian class person. consider the following figure: -
I want to get a Fact that is related to Peter and Elliss, or brothers and sisters, since they are both related to Jack. Any rough hint on how to achieve this using OWL API 4.0.
My complete owl file is attached: -
<?xml version="1.0"?>
<!DOCTYPE Ontology [
<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#" >
<!ENTITY xml "http://www.w3.org/XML/1998/namespace" >
<!ENTITY rdfs "http://www.w3.org/2000/01/rdf-schema#" >
<!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
]>
<Ontology xmlns="http://www.w3.org/2002/07/owl#"
xml:base="http://www.semanticweb.org/antonio/ontologies/2014/11/untitled-ontology-46"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:xml="http://www.w3.org/XML/1998/namespace"
ontologyIRI="http://www.semanticweb.org/antonio/ontologies/2014/11/untitled-ontology-
46">
<Prefix name="rdf" IRI="http://www.w3.org/1999/02/22-rdf-syntax-ns#"/>
<Prefix name="rdfs" IRI="http://www.w3.org/2000/01/rdf-schema#"/>
<Prefix name="xsd" IRI="http://www.w3.org/2001/XMLSchema#"/>
<Prefix name="owl" IRI="http://www.w3.org/2002/07/owl#"/>
<Declaration>
<Class IRI="#Gaurdian"/>
</Declaration>
<Declaration>
<Class IRI="#Ward"/>
</Declaration>
<Declaration>
<ObjectProperty IRI="#isWardOf"/>
</Declaration>
<Declaration>
<NamedIndividual IRI="#Allice"/>
</Declaration>
<Declaration>
<NamedIndividual IRI="#Amber"/>
</Declaration>
<Declaration>
<NamedIndividual IRI="#Jack"/>
</Declaration>
<Declaration>
<NamedIndividual IRI="#Paul"/>
</Declaration>
<Declaration>
<NamedIndividual IRI="#Peter"/>
</Declaration>
<ClassAssertion>
<Class IRI="#Ward"/>
<NamedIndividual IRI="#Allice"/>
</ClassAssertion>
<ClassAssertion>
<Class IRI="#Gaurdian"/>
<NamedIndividual IRI="#Amber"/>
</ClassAssertion>
<ClassAssertion>
<Class IRI="#Gaurdian"/>
<NamedIndividual IRI="#Jack"/>
</ClassAssertion>
<ClassAssertion>
<Class IRI="#Ward"/>
<NamedIndividual IRI="#Paul"/>
</ClassAssertion>
<ClassAssertion>
<Class IRI="#Ward"/>
<NamedIndividual IRI="#Peter"/>
</ClassAssertion>
<ObjectPropertyAssertion>
<ObjectProperty IRI="#isWardOf"/>
<NamedIndividual IRI="#Allice"/>
<NamedIndividual IRI="#Jack"/>
</ObjectPropertyAssertion>
<ObjectPropertyAssertion>
<ObjectProperty IRI="#isWardOf"/>
<NamedIndividual IRI="#Amber"/>
<NamedIndividual IRI="#Jack"/>
</ObjectPropertyAssertion>
<ObjectPropertyAssertion>
<ObjectProperty IRI="#isWardOf"/>
<NamedIndividual IRI="#Paul"/>
<NamedIndividual IRI="#Amber"/>
</ObjectPropertyAssertion>
<ObjectPropertyDomain>
<ObjectProperty IRI="#isWardOf"/>
<Class IRI="#Ward"/>
</ObjectPropertyDomain>
<ObjectPropertyRange>
<ObjectProperty IRI="#isWardOf"/>
<Class IRI="#Gaurdian"/>
</ObjectPropertyRange>
</Ontology> >
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Here is the easiest way I could think of. This includes reasoning with denominations, so it can be costly. However, if the ontology is not too large, this approach is possible.
The idea is to get all instances of each gaurdian. Then, for each such individual, we get all the persons that are associated with it by the isWard property. These sets will be what you are looking for if their size is greater than 1 (if the set size is one, then there is only one Ward for a given Gaurdian). The OWL API code for this would be similar to:
// load an ontology
OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
OWLOntology ontology = manager.loadOntologyFromOntologyDocument(ONTOLOGY_IRI);
OWLDataFactory df = manager.getOWLDataFactory();
// We need a reasoner to ask for individuals
OWLReasoner reasoner = createReasoner(ontology);
reasoner.precomputeInferences(InferenceType.CLASS_ASSERTIONS);
// get all the gaurdians in the ontology
OWLClass gaurdian = df.getOWLClass(IRI.create("#Gaurdian"));
Set<OWLNamedIndividual> gaurdians = reasoner.getInstances(gaurdian, false).getFlattened();
for (OWLNamedIndividual g : gaurdians) {
// all wards of a given gaurdian g
OWLObjectProperty isWardOf = df.getOWLObjectProperty(IRI.create("#isWardOf"));
OWLClassExpression wardsOfG = df.getOWLObjectHasValue(isWardOf, g);
// get all the wards related to a given gaurdian
Set<OWLNamedIndividual> wards = reasoner.getInstances(wardsOfG, false).getFlattened();
if ( wards.size() > 1 ) {
// this set of wards is connected to the same gaurdian
}
}
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the OWL API documentation has a link to the source code of the Rough Guide here
One of the tests extracts assertions for a property of an object, which you should adapt to your needs:
@Test
public void testIndividualAssertions() throws OWLException {
OWLOntologyManager m = create();
OWLOntology o = m.createOntology(EXAMPLE_IRI);
// We want to state that matthew has a father who is peter.
OWLIndividual matthew = df.getOWLNamedIndividual(IRI.create(EXAMPLE_IRI
+ "#matthew"));
OWLIndividual peter = df.getOWLNamedIndividual(IRI.create(EXAMPLE_IRI
+ "#peter"));
// We need the hasFather property
OWLObjectProperty hasFather = df.getOWLObjectProperty(IRI
.create(EXAMPLE_IRI + "#hasFather"));
// matthew --> hasFather --> peter
OWLObjectPropertyAssertionAxiom assertion = df
.getOWLObjectPropertyAssertionAxiom(hasFather, matthew, peter);
// Finally, add the axiom to our ontology and save
AddAxiom addAxiomChange = new AddAxiom(o, assertion);
m.applyChange(addAxiomChange);
// matthew is an instance of Person
OWLClass personClass = df.getOWLClass(IRI.create(EXAMPLE_IRI
+ "#Person"));
OWLClassAssertionAxiom ax = df.getOWLClassAssertionAxiom(personClass,
matthew);
// Add this axiom to our ontology - with a convenience method
m.addAxiom(o, ax);
}
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