[OWLAPI-developer] Reasoner and individuals

[Cédric P. <ced...@gm...>]

Hello,

I have a question about the use of reasoner to retrieve individuals.

My example is based on the pizza ontology (
http://www.co-ode.org/ontologies/pizza/2007/02/12/ ) wherein some pizzas
(like margherita) are classes and ingredients are (like mozzarella) are also
classes.

In order to learn how to use a reasoner (in this case Pellet) I wanted to
begin with a simple program to retrieve pizzas thanks to specific
ingredients.

Here is an example where I'm asking which pizzas has ham as an ingredient
(more precisely as a topping).

[code]
   Set<OWLDescription> descrCollection = new HashSet<OWLDescription>();
   OWLDataFactory dataFactory = manager.getOWLDataFactory();

   OWLObjectPropertyExpression prop =
dataFactory.getOWLObjectProperty(URI.create(ontology.getURI().toString()+"#"+"hasTopping"));
   OWLDescription topping =
dataFactory.getOWLClass(URI.create(ontology.getURI().toString()+"#"+"HamTopping"));
   OWLDescription toppingDesc =
dataFactory.getOWLObjectSomeRestriction(prop, topping);

   OWLDescription wantedDesc =
manager.getOWLDataFactory().getOWLObjectIntersectionOf(descrCollection);
   // Ask the reasoner for the subclasses of the description
   try {
            System.out.println(reasoner.getSubClasses(toppingDesc));
   }
   catch(OWLReasonerException e) {
            e.printStackTrace();
   }
[/code]

The result printed is "[[Parmense], [Capricciosa], [LaReine], [Siciliana]]"
and it is what I was expecting.

Now my question is: if pizzas and ingredients are changed into individuals
instead of classes (magherita as an individual of the class Pizza and ham as
an individual as the class Topping, etc…), how can I adapt (if it’s
possible) this code in order to obtain the same results?

I was thinking about changing "topping = dataFactory.getOWLClass(...)" into
" topping = dataFactory.getOWLIndividual(...)" and
"reasoner.getSubClasses(toppingDesc)" by
"reasoner.getIndividuals(toppingDesc, false)" but it's not working because
dataFactory.getOWLIndividual does not return any OWLDescription as needed
(and a cast seems not feasible).

Than you in advance for you help.

Regards,

Cedric