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 ForwardChain(FilmKnowledgeBase kb, ISentence sentence)
{
foreach (var kbSentence in kb.Sentences)
{
if (IsRenaiming(kbSentence, sentence))
{
return;
}
}
kb.Sentences.Add(sentence);
foreach (var kbSentence in kb.Sentences)
{
var innerSentence = DropOuterQuantifiers(kbSentence);
if (innerSentence.GetSentenceType() == SentenceType.SentenceConnectiveSentence)
{
var sentenceConnectiveSentence = innerSentence as SentenceConnectiveSentence;
if (sentenceConnectiveSentence.Connective == "->")
{
var anticedents = SentenceConnectiveSentence.GetAnticedents(sentenceConnectiveSentence);
for (int i = 0; i < anticedents.Count; ++i)
{
var unificationResult = Unify(anticedents[i], sentence);
if (unificationResult.Successful)
{
FindAndInfer(kb, anticedents.Take(i).Concat(anticedents.Skip(i + 1)).ToList(), //dropping unified sentence
sentenceConnectiveSentence.Sentence2, unificationResult);
}
}
}
}
}
}