在耶拿使用OWL.sameAs链接概念

Question

I am trying to tie up two identical individuals from different sources. My idea is that, if IndividualA has a missing property P but is tied up to IndividualB with an existing P using OWL.sameAs, then the inferencer should output that IndividualA has P! I am confused why this isn't working. This is my code.

public class Main {

static String NS_A = "http://www.namespacea.com/ontoa.owl#";
static String NS_B = "http://www.namespaceb.com/ontob.owl#";
static String NS_C = "http://www.namespacec.com/ontoc.owl#";

public static void main(String[] args) {

    OntModelSpec spec = OntModelSpec.OWL_MEM_MINI_RULE_INF;

    OntModel modelA = ModelFactory.createOntologyModel(spec);
    OntModel modelB = ModelFactory.createOntologyModel(spec);
    OntModel modelC = ModelFactory.createOntologyModel(spec);

    // Populate Model A
    OntClass animal = modelA.createClass(NS_A + "Animal");
    OntProperty hasFeathers = modelA.createOntProperty(NS_A + "hasFeathers");
    hasFeathers.addDomain(animal);
    hasFeathers.addRange(XSD.xboolean);

    // Populate Model B
    OntClass duck = modelB.createClass(NS_B + "Duck");
    duck.setSuperClass(animal);
    Individual donaldA = modelB.createIndividual(NS_B + "DonaldDuck", duck);

    // NEXT LINE IS REMOVED ON PURPOSE
    //donaldA.addLiteral(hasFeathers, true);

    //Populate Model C
    Individual donaldB = modelC.createIndividual(NS_C + "DonaldDuck", duck);

    // Donald hasFeathers IS DECLARED HERE
    donaldB.addLiteral(hasFeathers, true);

    // THIS TIES UP THE TWO INDIVIDUALS
    donaldA.addProperty(OWL.sameAs, donaldB);

    // Query
    System.out.println(
        "Does " + donaldA.getLocalName() +
        " have feathers? " + "Ans. " + donaldA.getPropertyValue(hasFeathers).asLiteral().getValue()
    );
}
}

The result is a NullPointerException. How do you solve this problem?

A more difficult scenario that I've thought of is, if there are Individuals A, B, C, D and E st A isSameAs B, B isSameAs C, and so forth, where E has P = true. Then asking if A has P = true should say TRUE!

Answer 1

Ok, I have posted the same question in the jena mailing list. Thanks for the update Ian. According to Dave Reynolds, The reasoner works within a model and not across different models.

Therefore the answer should be to use say, only modelA for instance so that all of the individuals are stored within it.