private Substitution BackChainList(Queue <ISentence> sentences, Substitution substitution)
{
Substitution answer = new Substitution();
if (sentences.Count == 0)
{
return(substitution);
}
var q = sentences.Dequeue();
foreach (var sen in Sentences)
{
var sub = Unify(q, sen);
if (sub.Successful)
{
substitution.Compose(sub);
}
}
foreach (var sen in Sentences
.Select(s => DropOuterQuantifiers(s))
.Where(s => s.GetSentenceType() == SentenceType.SentenceConnectiveSentence && (s as SentenceConnectiveSentence).Connective == "->")
.Select(s => s as SentenceConnectiveSentence))
{
var sub2 = Unify(q, sen.Sentence2);
if (sub2.Successful)
{
var qq = new Queue <ISentence>(SentenceConnectiveSentence.GetAnticedents(sen));
answer.Compose(BackChainList(new Queue <ISentence>(qq.Select(x => x.Substitute(sub2))), substitution.Compose(sub2)));
}
}
return(answer.Compose(BackChainList(sentences, substitution)));
}
public static void FindAndInfer(FilmKnowledgeBase kb, List <ISentence> premises, ISentence conclusion, Substitution s)
{
if (premises.Count == 0)
{
ForwardChain(kb, conclusion.Substitute(s));
}
foreach (var kbSentence in kb.Sentences)
{
var unifyResult = Unify(kbSentence, premises.First().Substitute(s));
if (unifyResult.Successful)
{
FindAndInfer(kb, premises.Skip(1).ToList(), conclusion, s.Compose(unifyResult));
}
}
}