如何检索由OWL API中的owl类实例实例化的属性？

Question

Using the OWL API, I'm trying to check whether a sub-class has actually instantiated the object properties that set it apart from those it inherits from the parent class.

Is there a way to get the properties an instance has defined? My current approach is attempting to get the instances of an OWLClass as follows:

// OWLClass o_class <---valid OWLClass object (e.g. City, Capital, etc)
Set<OWLNamedIndividual> o_instances = reasoner.getInstances(o_class, true).getFlattened();
for (OWLNamedIndividual> inst : o_instances) {
    //get set of properties defined by each instance
}

I've tried a few different methods, to no avail. inst.getObjectPropertiesInSignature() returns nothing. An sample of one of the OWL files I'm using is shown below:

<owl:Class rdf:ID="City">
    <owl:Restriction>
        <owl:onProperty>
            <owl:ObjectProperty rdf:about="#hasAccommodation"/>
        </owl:onProperty>
        <owl:someValuesFrom rdf:resource="#LuxuryHotel"/>
    </owl:Restriction>
 </owl:Class>

 <owl:Class rdf:ID="Capital">
     <rdfs:subClassOf>
        <owl:Restriction>
          <owl:someValuesFrom rdf:resource="#Museums"/>
          <owl:onProperty>
            <owl:ObjectProperty rdf:about="#hasActivity"/>
          </owl:onProperty>
        </owl:Restriction>
     </rdfs:subClassOf>
     <rdfs:subClassOf rdf:resource="#City"/>
 </owl:Class>

<Capital rdf:ID="Canberra">
    <hasAccommodation rdf:resource="#FourSeasons"/>
</Capital>
<Capital rdf:ID="Sydney">
    <hasAccommodation rdf:resource="#FourSeasons"/>
    <hasActivity rdf:resource="#CoolMuseum"/>
</Capital>

In the example above, I'd like to be able to detect that Canberra doesn't use the property hasActivity , while Sydney does. I'm not sure how to properly obtain those properties and compare them. For brevity, I excluded the lines for the FourSeasons and Museum stuff. I hope I've explained this decently enough.

Answer 1

Use the getObjectPropertyValues(OWLOntology ontology) method which is provided by the OWLIndividual Interface. It will return a Map with ObjectPropertyExpression as key and a Set of OWLIndivdual as value.