ya thanks Taylor... is it possible to map without creating a 3rd ontology?
On Tue, Apr 16, 2013 at 5:57 AM, Joshua TAYLOR <[email protected]>wrote: > On Mon, Apr 15, 2013 at 1:15 PM, aarthi <[email protected]> wrote: > > hi i have two ontology.. consider ont1 and ont2. if both ont1 and ont2 > > have a class named employee. And ont1's employee class have a sub > > class named age. but ont2's employee class doesn't have that class. i > > need to specify a relation that age "is-a" subclass of ont2's employee > > class. how to do that using jena? anyone help me > > I don't know how much sense it makes to talk about "Age" being a > subclass of "Employee", since ages aren't employees (in any meaningful > sense that I'm aware of, anyhow). But it's not hard to state that > ont1's Employees is an equivalent class to ont2's Employee, and > thereby be able to infer that ont2's Employee has the same subclasses. > Here's some code that does just that. The output is: > > 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.ModelFactory; > import com.hp.hpl.jena.rdf.model.StmtIterator; > import com.hp.hpl.jena.util.iterator.ExtendedIterator; > import com.hp.hpl.jena.vocabulary.OWL; > import com.hp.hpl.jena.vocabulary.RDFS; > > public class MappingOntologies { > public static void main(String[] args) { > // In most cases, the ontologies already exist, but since > we do not have > // sample data here, we create minimal ontologies that > have the classes > // that were mentioned, namely Ont1 that has a class > Employee with a > // subclass Age, and Ont2 that has a class Employee. > > // Ont1 > String NS1 = "http://www.example.com/ont1/";; > OntModel ont1 = ModelFactory.createOntologyModel( > OntModelSpec.OWL_DL_MEM ); > OntClass employee1 = ont1.createClass( NS1 + "Employee" ); > OntClass age1 = ont1. createClass( NS1 + "Age" ); > employee1.addSubClass( age1 ); > > // Ont2 > String NS2 = "http://www.example.com/ont2/";; > OntModel ont2 = ModelFactory.createOntologyModel( > OntModelSpec.OWL_DL_MEM ); > OntClass employee2 = ont2.createClass( NS2 + "Employee" ); > > // Usually when we merge or map ontologies, we are not > modifying either > // ontology, but actually creating some third ontology > that imports the > // others, and adding the mapping axioms to that third > ontology. In OWL > // we would probably do this using owl:imports, but in the > Jena API we > // can just create the third model and add the first two > as submodels. > > // Ont3; we make this one an inference model so that we > can get the > // inference that employee2 has age1 is a subclass of > employee2. > OntModel ont3 = ModelFactory.createOntologyModel( > OntModelSpec.OWL_DL_MEM_RULE_INF ); > > // add the submodels > ont3.addSubModel( ont1 ); > ont3.addSubModel( ont2 ); > > // assert that employee1 is equivalent to employee2 > ont3.add( employee1, OWL.equivalentClass, employee2 ); > > // To see the subclasses of employee2 in the merged/mapped > ontology, > // ask for statements of the form [x, rdfs:subClassOf, > employee2]. Each > // x is a subclass of employee2. > StmtIterator axioms = ont3.listStatements( null, > RDFS.subClassOf, employee2 ); > System.out.println( "Subclasses of "+employee2 ); > while ( axioms.hasNext() ) { > System.out.println( > "\t"+axioms.next().getSubject() ); > } > > // Alternatively, you could get the employee2 OntClass > from the merged > // model and list its subclasses. It is important to > retrieve the > // OntClass from the merged model, because that is the > model that > // OntClass#listSubClasses will query. > // > // Note: when I run this query, I only one less result > than I do > // in the previous query. I do not see the (trivial) > result that > // employee2 is a subclass of itself. Depending on your > intended > // use, this might be a reason to favor the first approach. > OntClass employee32 = ont3.getOntClass( NS2 + "Employee" ); > ExtendedIterator<OntClass> subclasses = > employee32.listSubClasses(); > System.out.println( "Subclasses of "+employee32 ); > while ( subclasses.hasNext() ) { > System.out.println( "\t"+subclasses.next() ); > } > } > } > > This outputs the following. See the comments in the code to explain > the different results from different query methods. > > Subclasses of http://www.example.com/ont2/Employee > http://www.example.com/ont1/Age > http://www.example.com/ont1/Employee > http://www.example.com/ont2/Employee > Subclasses of http://www.example.com/ont2/Employee > http://www.example.com/ont1/Age > http://www.example.com/ont1/Employee > > Hope this helps, > //JT > -- > Joshua Taylor, http://www.cs.rpi.edu/~tayloj/ >
