下面的代码创建了一个带有 B 和 A 类的简单 OntModel,其中 B ⊑ A,i 是 B 类型的个体。我们可以推断,例如,i 是 A 的一个实例,我们会看到在结果中。
import org.mindswap.pellet.jena.PelletReasonerFactory;
import com.hp.hpl.jena.ontology.OntClass;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.ontology.OntModelSpec;
import com.hp.hpl.jena.rdf.model.InfModel;
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.impl.StmtIteratorImpl;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;
import com.hp.hpl.jena.util.iterator.Filter;
public class JustTheDeductionsPlease {
public static void main(String[] args) {
// Create the base model. B is a subclass of A, and i is an instance of B.
String NS = "http://example.org/";
final OntModel model = ModelFactory.createOntologyModel( OntModelSpec.OWL_DL_MEM );
OntClass a = model.createClass( NS+"A" );
OntClass b = model.createClass( NS+"B" );
a.addSubClass( b );
model.createIndividual( NS+"i", b );
// Create the inference model.
InfModel pModel = ModelFactory.createInfModel( PelletReasonerFactory.theInstance().create(), model);
// An iterator over the statements of pModel that *aren't* in the base model.
ExtendedIterator<Statement> stmts = pModel.listStatements().filterDrop( new Filter<Statement>() {
@Override
public boolean accept(Statement o) {
return model.contains( o );
}
});
// For convenient printing, we create a model for the deductions.
// (If stmts were a StmtIterator, we could add it directly. It's not,
// so we end up creating a new StmtIteratorImpl, which is kludgey, but
// it's more efficient than converting the thing to a list.)
Model deductions = ModelFactory.createDefaultModel().add( new StmtIteratorImpl( stmts ));
deductions.write( System.out, "TTL" );
}
}
整个输出有点大,因为有很多纯粹基于 OWL 的结论。我们最清楚地看到纯演绎结果的地方是我们定义的班级和个人。请注意,例如,B 被列为其自身和 owl:Thing 的子类,但不是 A 的子类(因为在原始模型中),并且 i 具有类型 owl:Thing 和 A,但不是 B(因为这也在原始模型中):
<http://example.org/A>
<http://www.w3.org/2000/01/rdf-schema#subClassOf>
<http://www.w3.org/2002/07/owl#Thing> , <http://example.org/A> ;
<http://www.w3.org/2002/07/owl#disjointWith>
<http://www.w3.org/2002/07/owl#Nothing> ;
<http://www.w3.org/2002/07/owl#equivalentClass>
<http://example.org/A> .
<http://example.org/B>
<http://www.w3.org/2000/01/rdf-schema#subClassOf>
<http://www.w3.org/2002/07/owl#Thing> , <http://example.org/B> ;
<http://www.w3.org/2002/07/owl#disjointWith>
<http://www.w3.org/2002/07/owl#Nothing> ;
<http://www.w3.org/2002/07/owl#equivalentClass>
<http://example.org/B> .
<http://example.org/i>
a <http://www.w3.org/2002/07/owl#Thing> , <http://example.org/A> ;
<http://www.w3.org/2002/07/owl#sameAs>
<http://example.org/i> .