private void Ask(LinkedList<Expression> goals, KnowledgeBase context, Substitution theta, ProverCache cache, VariableRenamer renamer, bool askOne, HashSet<Substitution> results, HashSet<Fact> alreadyAsking) { if (goals.Count == 0) results.Add(theta); else { Expression literal = goals.First.Value; goals.RemoveFirst(); Expression qPrime = Substituter.Substitute(literal, theta); var fact = qPrime as Fact; if (fact != null && fact.RelationName == GameContainer.Parser.TokDistinct) AskDistinct(fact, goals, context, theta, cache, renamer, askOne, results, alreadyAsking); else { var negation = qPrime as Negation; if (negation != null) AskNot(negation, goals, context, theta, cache, renamer, askOne, results, alreadyAsking); else { var disjunction = qPrime as Disjunction; if (disjunction != null) AskOr(disjunction, goals, context, theta, cache, renamer, askOne, results, alreadyAsking); else { var sentence = (Fact) qPrime; AskSentence(sentence, goals, context, theta, cache, renamer, askOne, results, alreadyAsking); } } } goals.AddFirst(literal); } }
private void AskDistinct(Fact distinct, LinkedList<Expression> goals, KnowledgeBase context, Substitution theta, ProverCache cache, VariableRenamer renamer, bool askOne, HashSet<Substitution> results, HashSet<Fact> alreadyAsking) { if (!distinct.GetTerm(0).Equals(distinct.GetTerm(1))) Ask(goals, context, theta, cache, renamer, askOne, results, alreadyAsking); }
public AimaProver(IList<Expression> description) { description = DistinctAndNotMover.Run(description); _knowledgeBase = new KnowledgeBase(description); }
private void AskSentence(Fact sentence, LinkedList<Expression> goals, KnowledgeBase context, Substitution theta, ProverCache cache, VariableRenamer renamer, bool askOne, HashSet<Substitution> results, HashSet<Fact> alreadyAsking) { if (!cache.Contains(sentence)) { //Prevent infinite loops on certain recursive queries. if(alreadyAsking.Contains(sentence)) { return; } alreadyAsking.Add(sentence); List<Implication> candidates = new List<Implication>(); candidates.AddRange(_knowledgeBase.Fetch(sentence)); candidates.AddRange(context.Fetch(sentence)); var sentenceResults = new HashSet<Substitution>(); foreach (Implication rule in candidates) { Implication r = renamer.Rename(rule); Substitution thetaPrime = Unifier.Unify(r.Consequent, sentence); if (thetaPrime != null) { LinkedList<Expression> sentenceGoals = new LinkedList<Expression>(); for (int i = 0; i < r.NumAntecedents(); i++) sentenceGoals.AddLast(r.Antecedents.Constituents[i]); Ask(sentenceGoals, context, theta.Compose(thetaPrime), cache, renamer, false, sentenceResults, alreadyAsking); } } cache[sentence] = sentenceResults; alreadyAsking.Remove(sentence); } foreach (Substitution thetaPrime in cache[sentence]) { Ask(goals, context, theta.Compose(thetaPrime), cache, renamer, askOne, results, alreadyAsking); if (askOne && (results.Any())) break; } }
private void AskOr(Disjunction or, LinkedList<Expression> goals, KnowledgeBase context, Substitution theta, ProverCache cache, VariableRenamer renamer, bool askOne, HashSet<Substitution> results, HashSet<Fact> alreadyAsking) { foreach (Expression expression in or.Constituents) { goals.AddFirst(expression); Ask(goals, context, theta, cache, renamer, askOne, results, alreadyAsking); goals.RemoveFirst(); if (askOne && (results.Any())) break; } }
private void AskNot(Negation not, LinkedList<Expression> goals, KnowledgeBase context, Substitution theta, ProverCache cache, VariableRenamer renamer, bool askOne, HashSet<Substitution> results, HashSet<Fact> alreadyAsking) { var notGoals = new LinkedList<Expression>(); notGoals.AddLast(not.Negated); var notResults = new HashSet<Substitution>(); Ask(notGoals, context, theta, cache, renamer, true, notResults, alreadyAsking); if (notResults.Count == 0) Ask(goals, context, theta, cache, renamer, askOne, results, alreadyAsking); }