public Object getMatrixValue(OWLObject entity, Object prop) {
   if (entity instanceof OWLIndividual) {
     if (prop instanceof OWLObjectProperty) {
       return helper.getRelationships((OWLIndividual) entity, (OWLObjectProperty) prop);
     } else if (prop instanceof OWLDataProperty) {
       return helper.getRelationships((OWLIndividual) entity, (OWLDataProperty) prop);
     } else {
       return super.getMatrixValue(entity, prop);
     }
   }
   return null;
 }