public AllSubstitution FOL_BC_AND(List<Predicate> goal, AllSubstitution theta) {
//
if (theta.status == false) return theta;
else if (goal.size() == 0) return theta;
else {
Predicate first = goal.get(0); // n
first = substFromTheata(theta, first);
int index = 0;
int tSize =
(KBObj.KB.get(first.fnName) == null)
? 0
: (KBObj.KB.get(first.fnName).sentences.size() - 1);
while (index <= tSize) {
AllSubstitution thetaPrime = FOL_BC_OR(first, theta, index++);
if (thetaPrime.status && goal.size() > 1) {
List<Predicate> rest =
new ArrayList<Predicate>(((ArrayList<Predicate>) goal).subList(1, goal.size()));
AllSubstitution thetaDoublePrime = FOL_BC_AND(rest, sumUpTheta(theta, thetaPrime));
if (thetaDoublePrime.status) return thetaDoublePrime;
} else return thetaPrime;
}
AllSubstitution t = new AllSubstitution();
t.status = false;
return t;
}
}
public AllSubstitution FOL_BC_OR(Predicate goal, AllSubstitution theta, int index) {
// the key is the function name of query. H(x), H is key.
String key = goal.fnName;
// get all the sentence which has conclusion as goal.
List<Sentence> sents = (KBObj.KB.get(key) == null) ? null : KBObj.KB.get(key).sentences;
if (sents != null) {
// Iterate through all the sentence which have conclusion as sentence.
// for (Sentence sentence : sents) {
for (int i = index; i < sents.size(); i++) {
Sentence sentence = sents.get(i);
AllSubstitution subst = UNIFY(sentence.rhs, goal, sentence);
AllSubstitution thetaPrime = FOL_BC_AND(sentence.lhs, subst);
if (thetaPrime != null && thetaPrime.status) {
return thetaPrime;
}
}
}
AllSubstitution t = new AllSubstitution();
t.status = false;
return t;
}