// The next few routines convert a set of axioms from a StatementSource
// into a data structure of use for the algorithm, with Sequents and things.
private static Hashtable RulesToCases(StatementSource rules)
{
Hashtable cases = new Hashtable();
MemoryStore rules_store = new MemoryStore(rules);
foreach (Statement p in rules_store) {
if (p.Meta == Statement.DefaultMeta) {
if (p.Predicate == entLOGIMPLIES && p.Object is Entity) {
MemoryStore body = new MemoryStore();
MemoryStore head = new MemoryStore();
rules_store.Select(new Statement(null, null, null, (Entity)p.Subject), new RemoveMeta(body));
rules_store.Select(new Statement(null, null, null, (Entity)p.Object), new RemoveMeta(head));
// Any variables in the head not bound in the body represent existentially closed bnodes.
// (Euler's OWL test case does this. Wish they had used bnodes instead of vars...)
ResSet bodyvars = new ResSet();
foreach (Statement b in body) {
if (b.Subject is Variable) bodyvars.Add(b.Subject);
if (b.Predicate is Variable) bodyvars.Add(b.Predicate);
if (b.Object is Variable) bodyvars.Add(b.Object);
}
foreach (Entity v in head.GetEntities()) {
if (v is Variable && !bodyvars.Contains(v))
head.Replace(v, new BNode(((Variable)v).LocalName));
}
// Replace (...) lists in the body that are tied to the subjects
// of user predicates with callArgs objects.
Hashtable callArgs = new Hashtable();
CollectCallArgs(body, callArgs);
// Rules can't have more than one statement in their
// consequent. The best we can do is break up
// the consequent into multiple rules. (Since all head
// variables are bound in body, it's equivalent...?)
foreach (Statement h in head)
AddSequent(cases, new Sequent(h, body.ToArray(), callArgs));
} else {
AddSequent(cases, new Sequent(p, new Statement[0], null));
}
}
}
return cases;
}