// END-Sentence // public override bool Equals(Object o) { if (this == o) { return(true); } if ((o == null) || !(o is NotSentence)) { return(false); } NotSentence ns = (NotSentence)o; return(ns.negated.Equals(negated)); }
protected void testFullFOLKBLovesAnimalQueryNotKillsJackTunaSucceeds( InferenceProcedure infp, bool expectedToTimeOut) { FOLKnowledgeBase akb = FOLKnowledgeBaseFactory .createLovesAnimalKnowledgeBase(infp); List<Term> terms = new List<Term>(); terms.Add(new Constant("Jack")); terms.Add(new Constant("Tuna")); NotSentence query = new NotSentence(new Predicate("Kills", terms)); InferenceResult answer = akb.ask(query); Assert.IsTrue(null != answer); if (expectedToTimeOut) { Assert.IsFalse(answer.isPossiblyFalse()); Assert.IsFalse(answer.isTrue()); Assert.IsTrue(answer.isUnknownDueToTimeout()); Assert.IsFalse(answer.isPartialResultDueToTimeout()); Assert.IsTrue(0 == answer.getProofs().Count); } else { Assert.IsFalse(answer.isPossiblyFalse()); Assert.IsTrue(answer.isTrue()); Assert.IsFalse(answer.isUnknownDueToTimeout()); Assert.IsFalse(answer.isPartialResultDueToTimeout()); Assert.IsTrue(1 == answer.getProofs().Count); Assert.IsTrue(0 == answer.getProofs()[0] .getAnswerBindings().Count); } }
// // PRIVATE METHODS // private void constructFOLEg() { ithExampleConstant = new Constant(folDSDomain.getExampleConstant(egNo)); List<Term> terms = new List<Term>(); terms.Add(ithExampleConstant); // Create the classification sentence classification = new Predicate(folDSDomain.getGoalPredicateName(), terms); if (!example.getAttributeValueAsString( folDSDomain.getDataSetTargetName()).Equals( folDSDomain.getTrueGoalValue())) { // if not true then needs to be a Not sentence classification = new NotSentence(classification); } // Create the description sentence List<Sentence> descParts = new List<Sentence>(); foreach (String dname in folDSDomain.getDescriptionDataSetNames()) { String foldDName = folDSDomain.getFOLName(dname); terms = new List<Term>(); terms.Add(ithExampleConstant); // If multivalued becomes a two place predicate // e.g: Patrons(X1, Some) // otherwise: Hungry(X1) or ~ Hungry(X1) // see pg 769 of AIMA Sentence part = null; if (folDSDomain.isMultivalued(dname)) { terms.Add(new Constant(folDSDomain.getFOLName(example .getAttributeValueAsString(dname)))); part = new Predicate(foldDName, terms); } else { part = new Predicate(foldDName, terms); // Need to determine if false if (!folDSDomain.getTrueGoalValue().Equals( example.getAttributeValueAsString(dname))) { part = new NotSentence(part); } } descParts.Add(part); } if (descParts.Count == 1) { description = descParts[0]; } else if (descParts.Count > 1) { description = new ConnectedSentence(Connectors.AND, descParts [0], descParts[1]); for (int i = 2; i < descParts.Count; i++) { description = new ConnectedSentence(Connectors.AND, description, descParts[i]); } } }
public Object visitNotSentence(NotSentence sentence, Object arg) { sentence.getNegated().accept(this, arg); return arg; }
public Object visitNotSentence(NotSentence sentence, Object arg) { ArgData ad = (ArgData)arg; // Indicate that the enclosed predicate is negated ad.negated = true; sentence.getNegated().accept(this, arg); ad.negated = false; return sentence; }
public Object visitNotSentence(NotSentence sentence, Object arg) { return new NotSentence((Sentence)sentence.getNegated().accept(this, arg)); }
public Object visitNotSentence(NotSentence notSentence, Object arg) { // CNF requires NOT (~) to appear only in literals, so we 'move ~ // inwards' by repeated application of the following equivalences: Sentence negated = notSentence.getNegated(); // ~(~alpha) equivalent to alpha (double negation elimination) if (negated is NotSentence) { return ((NotSentence)negated).getNegated().accept(this, arg); } if (negated is ConnectedSentence) { ConnectedSentence negConnected = (ConnectedSentence)negated; Sentence alpha = negConnected.getFirst(); Sentence beta = negConnected.getSecond(); // ~(alpha ^ beta) equivalent to (~alpha V ~beta) (De Morgan) if (Connectors.isAND(negConnected.getConnector())) { // I need to ensure the ~s are moved in deeper Sentence notAlpha = (Sentence)(new NotSentence(alpha)).accept( this, arg); Sentence notBeta = (Sentence)(new NotSentence(beta)).accept( this, arg); return new ConnectedSentence(Connectors.OR, notAlpha, notBeta); } // ~(alpha V beta) equivalent to (~alpha ^ ~beta) (De Morgan) if (Connectors.isOR(negConnected.getConnector())) { // I need to ensure the ~s are moved in deeper Sentence notAlpha = (Sentence)(new NotSentence(alpha)).accept( this, arg); Sentence notBeta = (Sentence)(new NotSentence(beta)).accept( this, arg); return new ConnectedSentence(Connectors.AND, notAlpha, notBeta); } } // in addition, rules for negated quantifiers: if (negated is QuantifiedSentence) { QuantifiedSentence negQuantified = (QuantifiedSentence)negated; // I need to ensure the ~ is moved in deeper Sentence notP = (Sentence)(new NotSentence(negQuantified .getQuantified())).accept(this, arg); // ~FORALL x p becomes EXISTS x ~p if (Quantifiers.isFORALL(negQuantified.getQuantifier())) { return new QuantifiedSentence(Quantifiers.EXISTS, negQuantified .getVariables(), notP); } // ~EXISTS x p becomes FORALL x ~p if (Quantifiers.isEXISTS(negQuantified.getQuantifier())) { return new QuantifiedSentence(Quantifiers.FORALL, negQuantified .getVariables(), notP); } } return new NotSentence((Sentence)negated.accept(this, arg)); }
public Object visitNotSentence(NotSentence notSentence, Object arg) { Sentence negated = notSentence.getNegated(); return new NotSentence((Sentence)negated.accept(this, arg)); }
public AnswerHandler(FOLKnowledgeBase kb, Sentence aQuery, long maxQueryTime, FOLModelElimination folModelElimination) { finishTime = System.DateTime.UtcNow.Ticks + maxQueryTime; Sentence refutationQuery = new NotSentence(aQuery); // Want to use an answer literal to pull // query variables where necessary Literal answerLiteral = kb.createAnswerLiteral(refutationQuery); answerLiteralVariables = kb.collectAllVariables(answerLiteral .getAtomicSentence()); // Create the Set of Support based on the Query. if (answerLiteralVariables.Count > 0) { Sentence refutationQueryWithAnswer = new ConnectedSentence( Connectors.OR, refutationQuery, (Sentence)answerLiteral .getAtomicSentence().copy()); sos = folModelElimination.createChainsFromClauses(kb .convertToClauses(refutationQueryWithAnswer)); answerChain.addLiteral(answerLiteral); } else { sos = folModelElimination.createChainsFromClauses(kb .convertToClauses(refutationQuery)); } foreach (Chain s in sos) { s.setProofStep(new ProofStepGoal(s)); } }
// // START-InferenceProcedure public InferenceResult ask(FOLKnowledgeBase KB, Sentence alpha) { List<Clause> sos = new List<Clause>(); List<Clause> usable = new List<Clause>(); // Usable set will be the set of clauses in the KB, // are assuming this is satisfiable as using the // Set of Support strategy. foreach (Clause c in KB.getAllClauses()) { Clause c2 = KB.standardizeApart(c); c2.setStandardizedApartCheckNotRequired(); usable.AddRange(c2.getFactors()); } // Ensure reflexivity axiom is added to usable if using paramodulation. if (isUseParamodulation()) { // Reflexivity Axiom: x = x TermEquality reflexivityAxiom = new TermEquality(new Variable("x"), new Variable("x")); Clause reflexivityClause = new Clause(); reflexivityClause.addLiteral(new Literal(reflexivityAxiom)); reflexivityClause = KB.standardizeApart(reflexivityClause); reflexivityClause.setStandardizedApartCheckNotRequired(); usable.Add(reflexivityClause); } Sentence notAlpha = new NotSentence(alpha); // Want to use an answer literal to pull // query variables where necessary Literal answerLiteral = KB.createAnswerLiteral(notAlpha); List<Variable> answerLiteralVariables = KB .collectAllVariables(answerLiteral.getAtomicSentence()); Clause answerClause = new Clause(); if (answerLiteralVariables.Count > 0) { Sentence notAlphaWithAnswer = new ConnectedSentence(Connectors.OR, notAlpha, answerLiteral.getAtomicSentence()); foreach (Clause c in KB.convertToClauses(notAlphaWithAnswer)) { Clause c2 = KB.standardizeApart(c); c2.setProofStep(new ProofStepGoal(c2)); c2.setStandardizedApartCheckNotRequired(); sos.AddRange(c2.getFactors()); } answerClause.addLiteral(answerLiteral); } else { foreach (Clause c in KB.convertToClauses(notAlpha)) { Clause c2 = KB.standardizeApart(c); c2.setProofStep(new ProofStepGoal(c2)); c2.setStandardizedApartCheckNotRequired(); sos.AddRange(c2.getFactors()); } } // Ensure all subsumed clauses are removed foreach (Clause c in SubsumptionElimination.findSubsumedClauses(usable)) { usable.Remove(c); } foreach (Clause c in SubsumptionElimination.findSubsumedClauses(sos)) { sos.Remove(c); } OTTERAnswerHandler ansHandler = new OTTERAnswerHandler(answerLiteral, answerLiteralVariables, answerClause, maxQueryTime); IndexedClauses idxdClauses = new IndexedClauses( getLightestClauseHeuristic(), sos, usable); return otter(ansHandler, idxdClauses, sos, usable); }
// // START-InferenceProcedure /** * <code> * function FOL-FC-ASK(KB, alpha) returns a substitution or false * inputs: KB, the knowledge base, a set of first order definite clauses * alpha, the query, an atomic sentence * </code> */ public InferenceResult ask(FOLKnowledgeBase KB, Sentence query) { // Assertions on the type of queries this Inference procedure // supports if (!(query is AtomicSentence)) { throw new ArgumentException( "Only Atomic Queries are supported."); } FCAskAnswerHandler ansHandler = new FCAskAnswerHandler(); Literal alpha = new Literal((AtomicSentence)query); // local variables: new, the new sentences inferred on each iteration List<Literal> newSentences = new List<Literal>(); // Ensure query is not already a know fact before // attempting forward chaining. List<Dictionary<Variable, Term>> answers = KB.fetch(alpha); if (answers.Count > 0) { ansHandler.addProofStep(new ProofStepFoChAlreadyAFact(alpha)); ansHandler.setAnswers(answers); return ansHandler; } // repeat until new is empty do { // new <- {} newSentences.Clear(); // for each rule in KB do // (p1 ^ ... ^ pn => q) <-STANDARDIZE-VARIABLES(rule) foreach (Clause impl in KB.getAllDefiniteClauseImplications()) { Clause impl2 = KB.standardizeApart(impl); // for each theta such that SUBST(theta, p1 ^ ... ^ pn) = // SUBST(theta, p'1 ^ ... ^ p'n) // --- for some p'1,...,p'n in KB foreach (Dictionary<Variable, Term> theta in KB.fetch(invert(new List<Literal>(impl2 .getNegativeLiterals())))) { // q' <- SUBST(theta, q) Literal qPrime = KB.subst(theta, impl.getPositiveLiterals() [0]); // if q' does not unify with some sentence already in KB or // new then do if (!KB.isRenaming(qPrime) && !KB.isRenaming(qPrime, newSentences)) { // add q' to new newSentences.Add(qPrime); ansHandler.addProofStep(impl, qPrime, theta); // theta <- UNIFY(q', alpha) Dictionary<Variable, Term> theta2 = KB.unify(qPrime.getAtomicSentence(), alpha .getAtomicSentence()); // if theta is not fail then return theta if (null != theta2) { foreach (Literal l in newSentences) { Sentence s = null; if (l.isPositiveLiteral()) { s = l.getAtomicSentence(); } else { s = new NotSentence(l.getAtomicSentence()); } KB.tell(s); } ansHandler.setAnswers(KB.fetch(alpha)); return ansHandler; } } } } // add new to KB foreach (Literal l in newSentences) { Sentence s = null; if (l.isPositiveLiteral()) { s = l.getAtomicSentence(); } else { s = new NotSentence(l.getAtomicSentence()); } KB.tell(s); } } while (newSentences.Count > 0); // return false return ansHandler; }
public Object visitNotSentence(NotSentence sentence, Object arg) { throw new NotImplementedException( "visitNotSentence() should not be called."); }
// // START-InferenceProcedure public InferenceResult ask(FOLKnowledgeBase KB, Sentence alpha) { // clauses <- the set of clauses in CNF representation of KB ^ ~alpha List<Clause> clauses = new List<Clause>(); foreach (Clause c in KB.getAllClauses()) { Clause c2 = KB.standardizeApart(c); c2.setStandardizedApartCheckNotRequired(); clauses.AddRange(c2.getFactors()); } Sentence notAlpha = new NotSentence(alpha); // Want to use an answer literal to pull // query variables where necessary Literal answerLiteral = KB.createAnswerLiteral(notAlpha); List<Variable> answerLiteralVariables = KB .collectAllVariables(answerLiteral.getAtomicSentence()); Clause answerClause = new Clause(); if (answerLiteralVariables.Count > 0) { Sentence notAlphaWithAnswer = new ConnectedSentence(Connectors.OR, notAlpha, answerLiteral.getAtomicSentence()); foreach (Clause c in KB.convertToClauses(notAlphaWithAnswer)) { Clause c2 = KB.standardizeApart(c); c2.setProofStep(new ProofStepGoal(c2)); c2.setStandardizedApartCheckNotRequired(); clauses.AddRange(c2.getFactors()); } answerClause.addLiteral(answerLiteral); } else { foreach (Clause c in KB.convertToClauses(notAlpha)) { Clause c2 = KB.standardizeApart(c); c2.setProofStep(new ProofStepGoal(c2)); c2.setStandardizedApartCheckNotRequired(); clauses.AddRange(c2.getFactors()); } } TFMAnswerHandler ansHandler = new TFMAnswerHandler(answerLiteral, answerLiteralVariables, answerClause, maxQueryTime); // new <- {} List<Clause> newClauses = new List<Clause>(); List<Clause> toAdd = new List<Clause>(); // loop do int noOfPrevClauses = clauses.Count; do { if (null != tracer) { tracer.stepStartWhile(clauses, clauses.Count, newClauses .Count); } newClauses.Clear(); // for each Ci, Cj in clauses do Clause[] clausesA = new Clause[clauses.Count]; clausesA = clauses.ToArray(); // Basically, using the simple T)wo F)inger M)ethod here. for (int i = 0; i < clausesA.Length; i++) { Clause cI = clausesA[i]; if (null != tracer) { tracer.stepOuterFor(cI); } for (int j = i; j < clausesA.Length; j++) { Clause cJ = clausesA[j]; if (null != tracer) { tracer.stepInnerFor(cI, cJ); } // resolvent <- FOL-RESOLVE(Ci, Cj) List<Clause> resolvents = cI.binaryResolvents(cJ); if (resolvents.Count > 0) { toAdd.Clear(); // new <- new <UNION> resolvent foreach (Clause rc in resolvents) { toAdd.AddRange(rc.getFactors()); } if (null != tracer) { tracer.stepResolved(cI, cJ, toAdd); } ansHandler.checkForPossibleAnswers(toAdd); if (ansHandler.isComplete()) { break; } newClauses.AddRange(toAdd); } if (ansHandler.isComplete()) { break; } } if (ansHandler.isComplete()) { break; } } noOfPrevClauses = clauses.Count; // clauses <- clauses <UNION> new clauses.AddRange(newClauses); if (ansHandler.isComplete()) { break; } // if new is a <SUBSET> of clauses then finished // searching for an answer // (i.e. when they were added the # clauses // did not increase). } while (noOfPrevClauses < clauses.Count); if (null != tracer) { tracer.stepFinished(clauses, ansHandler); } return ansHandler; }