/**
* Example the conclusions graph for introduction of restrictions which require a comprehension
* rewrite and declare new (anon) classes for those restrictions.
*/
public void comprehensionAxioms(Model premises, Model conclusions) {
// Comprehend all restriction declarations and note them in a map
Map<Resource, Resource> comprehension = new HashMap<>();
StmtIterator ri = conclusions.listStatements(null, RDF.type, OWL.Restriction);
while (ri.hasNext()) {
Resource restriction = ri.nextStatement().getSubject();
StmtIterator pi = restriction.listProperties(OWL.onProperty);
while (pi.hasNext()) {
Resource prop = (Resource) pi.nextStatement().getObject();
StmtIterator vi = restriction.listProperties();
while (vi.hasNext()) {
Statement rs = vi.nextStatement();
if (!rs.getPredicate().equals(OWL.onProperty)) {
// Have a restriction on(prop) of type rs in the conclusions
// So assert a premise that such a restriction could exisit
Resource comp =
premises
.createResource()
.addProperty(RDF.type, OWL.Restriction)
.addProperty(OWL.onProperty, prop)
.addProperty(rs.getPredicate(), rs.getObject());
comprehension.put(restriction, comp);
}
}
}
}
// Comprehend any intersectionOf lists. Introduce anon class which has the form
// of the intersection expression.
// Rewrite queries of the form (X intersectionOf Y) to the form
// (X equivalentClass ?CC) (?CC intersectionOf Y)
StmtIterator ii = conclusions.listStatements(null, OWL.intersectionOf, (RDFNode) null);
List<Statement> intersections = new ArrayList<>();
while (ii.hasNext()) {
intersections.add(ii.nextStatement());
}
for (Statement is : intersections) {
// Declare in the premises that such an intersection exists
Resource comp =
premises
.createResource()
.addProperty(RDF.type, OWL.Class)
.addProperty(
OWL.intersectionOf, mapList(premises, (Resource) is.getObject(), comprehension));
// Rewrite the conclusions to be a test for equivalence between the class being
// queried and the comprehended interesection
conclusions.remove(is);
conclusions.add(is.getSubject(), OWL.equivalentClass, comp);
}
// Comprehend any oneOf lists
StmtIterator io = conclusions.listStatements(null, OWL.oneOf, (RDFNode) null);
while (io.hasNext()) {
Statement s = io.nextStatement();
Resource comp = premises.createResource().addProperty(OWL.oneOf, s.getObject());
}
}
/**
* Helper. Adds to the target model a translation of the given RDF list with each element replaced
* according to the map.
*/
private Resource mapList(Model target, Resource list, Map<Resource, Resource> map) {
if (list.equals(RDF.nil)) {
return RDF.nil;
} else {
Resource head = (Resource) list.getRequiredProperty(RDF.first).getObject();
Resource rest = (Resource) list.getRequiredProperty(RDF.rest).getObject();
Resource mapElt = target.createResource();
Resource mapHead = map.get(head);
if (mapHead == null) mapHead = head;
mapElt.addProperty(RDF.first, mapHead);
mapElt.addProperty(RDF.rest, mapList(target, rest, map));
return mapElt;
}
}