public bool?visitBinarySentence(ComplexSentence bs, bool?arg)
{
bool?firstValue = bs.getSimplerSentence(0).accept(this, null);
bool?secondValue = bs.getSimplerSentence(1).accept(this, null);
if ((firstValue == null) || (secondValue == null))
{
// strictly not true for or/and
// -FIX later
return(null);
}
else
{
Connective connective = bs.getConnective();
if (connective.Equals(Connective.AND))
{
return(firstValue.Value && secondValue.Value);
}
else if (connective.Equals(Connective.OR))
{
return(firstValue.Value || secondValue.Value);
}
else if (connective.Equals(Connective.IMPLICATION))
{
return(!(firstValue.Value && !secondValue.Value));
}
else if (connective.Equals(Connective.BICONDITIONAL))
{
return(firstValue.Equals(secondValue));
}
return(null);
}
}
public virtual Sentence visitBinarySentence(ComplexSentence s, A arg)
{
// a new Complex Sentence with the same connective but possibly
// with its simpler sentences replaced by the visitor.
return(new ComplexSentence(s.getConnective(), s.getSimplerSentence(0)
.accept(this, arg), s.getSimplerSentence(1).accept(this, arg)));
}
public virtual ISet <T> visitBinarySentence(ComplexSentence s, ISet <T> arg)
{
ISet <T> termunion = SetOps.union(
s.getSimplerSentence(0).accept(this, arg), s
.getSimplerSentence(1).accept(this, arg));
return(SetOps.union(arg, termunion));
}
protected ISet <Clause> setOfClausesInTheCNFRepresentationOfKBAndNotAlpha(KnowledgeBase kb, Sentence alpha)
{
// KB & ~alpha;
Sentence isContradiction = new ComplexSentence(Connective.AND,
kb.asSentence(), new ComplexSentence(Connective.NOT, alpha));
// the set of clauses in the CNF representation
ISet <Clause> clauses = CollectionFactory.CreateSet <Clause>(ConvertToConjunctionOfClauses.convert(isContradiction).getClauses());
discardTautologies(clauses);
return(clauses);
}
public bool?visitUnarySentence(ComplexSentence fs, bool?arg)
{
object negatedValue = fs.getSimplerSentence(0).accept(this, null);
if (negatedValue != null)
{
return(!((bool)negatedValue));
}
else
{
return(null);
}
}
public override ISet <Literal> visitBinarySentence(ComplexSentence s, ISet <Literal> arg)
{
if (s.isOrSentence())
{
s.getSimplerSentence(0).accept(this, arg);
s.getSimplerSentence(1).accept(this, arg);
}
else
{
throw new IllegalArgumentException("Sentence is not in CNF: " + s);
}
return(arg);
}
// No hace falta override porque PLVisitor es una interfaz
public bool?VisitBinarySentence(ComplexSentence bs, bool?arg)
{
bool? firstValue = (bool?)bs.GetSimplerSentence(0).Accept(this, null);
bool? secondValue = (bool?)bs.GetSimplerSentence(1).Accept(this, null);
bool bothValuesKnown = firstValue != null && secondValue != null;
Connective connective = bs.GetConnective();
// He reprogramado todo esto
if (connective.Equals(Connective.AND))
{
if (firstValue.Equals(false) || secondValue.Equals(false))
{
return(false);
}
else if (bothValuesKnown)
{
return(true); // Si no se cumple, saldrá como null
}
}
else if (connective.Equals(Connective.OR))
{
if (firstValue.Equals(true) || secondValue.Equals(true))
{
return(true);
}
else if (bothValuesKnown)
{
return(false); // Si no se cumple, saldrá como null
}
}
else if (connective.Equals(Connective.IMPLICATION))
{
if (firstValue.Equals(false) || secondValue.Equals(true))
{
return(true);
}
else if (bothValuesKnown)
{
return(false); // Si no se cumple, saldrá como null
}
}
else if (connective.Equals(Connective.BICONDITIONAL))
{
if (bothValuesKnown)
{
return(firstValue.Equals(secondValue)); // Si no se cumple, saldrá como null
}
}
return(null);
}
public override ISet <Clause> visitUnarySentence(ComplexSentence s, ISet <Clause> arg)
{
if (!s.getSimplerSentence(0).isPropositionSymbol())
{
throw new IllegalStateException("Sentence is not in CNF: " + s);
}
// a negative unit clause
Literal negativeLiteral = new Literal((PropositionSymbol)s.getSimplerSentence(0), false);
arg.Add(new Clause(negativeLiteral));
return(arg);
}
public override ISet <Literal> VisitUnarySentence(ComplexSentence s, ISet <Literal> arg)
{
if (!s.GetSimplerSentence(0).IsPropositionSymbol())
{
throw new InvalidOperationException("Sentence is not in CNF: " + s); //IllegalStateException
}
// un literal negativo
Literal negativeLiteral = new Literal((PropositionSymbol)s.GetSimplerSentence(0), false);
arg.Add(negativeLiteral);
return(arg);
}
//
// SUPPORTING CODE
//
/**
* Determine if KB |= α, i.e. alpha is entailed by KB.
*
* @param kb
* a Knowledge Base in propositional logic.
* @param alpha
* a propositional sentence.
* @return true, if α is entailed by KB, false otherwise.
*/
public bool isEntailed(KnowledgeBase kb, Sentence alpha)
{
// AIMA3e p.g. 260: kb |= alpha, can be done by testing
// unsatisfiability of kb & ~alpha.
ISet <Clause> kbAndNotAlpha = CollectionFactory.CreateSet <Clause>();
Sentence notQuery = new ComplexSentence(Connective.NOT, alpha);
ISet <PropositionSymbol> symbols = CollectionFactory.CreateSet <PropositionSymbol>();
ICollection <PropositionSymbol> querySymbols = CollectionFactory.CreateQueue <PropositionSymbol>(SymbolCollector.getSymbolsFrom(notQuery));
kbAndNotAlpha.AddAll(kb.asCNF());
kbAndNotAlpha.AddAll(ConvertToConjunctionOfClauses.convert(notQuery).getClauses());
symbols.AddAll(querySymbols);
symbols.AddAll(kb.getSymbols());
return(!dpll(kbAndNotAlpha, CollectionFactory.CreateQueue <PropositionSymbol>(symbols), new Model()));
}
public override Sentence VisitUnarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
Sentence negated = s.GetSimplerSentence(0);
if (negated.IsPropositionSymbol())
{
// Ya se ha movido completamente
result = s;
}
else if (negated.IsNotSentence())
{
// ~(~α) ≡ α (eliminación de la doble negación)
Sentence alpha = negated.GetSimplerSentence(0);
result = alpha.Accept(this, arg);
}
else if (negated.IsAndSentence() || negated.IsOrSentence())
{
Sentence alpha = negated.GetSimplerSentence(0);
Sentence beta = negated.GetSimplerSentence(1);
// Esto asegura que la eliminación de la doble negación sucede
Sentence notAlpha = (new ComplexSentence(Connective.NOT, alpha))
.Accept(this, null);
Sentence notBeta = (new ComplexSentence(Connective.NOT, beta))
.Accept(this, null);
if (negated.IsAndSentence())
{
// ~(α & β) ≡ (~α | ~β) (De Morgan)
result = new ComplexSentence(Connective.OR, notAlpha, notBeta);
}
else
{
// ~(α | β) ≡ (~α & ~β) (De Morgan)
result = new ComplexSentence(Connective.AND, notAlpha, notBeta);
}
}
else
{
throw new ArgumentException( //IllegalArgumentException
"Biconditionals and Implications should not exist in input: "
+ s);
}
return(result);
}
public override Sentence visitUnarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
Sentence negated = s.getSimplerSentence(0);
if (negated.isPropositionSymbol())
{
// Already moved in fully
result = s;
}
else if (negated.isNotSentence())
{
// ~(~α) ≡ α (double-negation elimination)
Sentence alpha = negated.getSimplerSentence(0);
result = alpha.accept(this, arg);
}
else if (negated.isAndSentence() || negated.isOrSentence())
{
Sentence alpha = negated.getSimplerSentence(0);
Sentence beta = negated.getSimplerSentence(1);
// This ensures double-negation elimination happens
Sentence notAlpha = (new ComplexSentence(Connective.NOT, alpha)).accept(this, null);
Sentence notBeta = (new ComplexSentence(Connective.NOT, beta)).accept(this, null);
if (negated.isAndSentence())
{
// ~(α & β) ≡ (~α | ~β) (De Morgan)
result = new ComplexSentence(Connective.OR, notAlpha, notBeta);
}
else
{
// ~(α | β) ≡ (~α & ~β) (De Morgan)
result = new ComplexSentence(Connective.AND, notAlpha, notBeta);
}
}
else
{
throw new IllegalArgumentException("Biconditionals and Implications should not exist in input: " + s);
}
return(result);
}
public override Sentence VisitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.IsImplicationSentence())
{
// Elimina =>, reemplazando & alpha; => β< br > con ~α | β
Sentence alpha = s.GetSimplerSentence(0).Accept(this, arg);
Sentence beta = s.GetSimplerSentence(1).Accept(this, arg);
Sentence notAlpha = new ComplexSentence(Connective.NOT, alpha);
result = new ComplexSentence(Connective.OR, notAlpha, beta);
}
else
{
result = base.VisitBinarySentence(s, arg);
}
return(result);
}
public override ISet <Clause> VisitBinarySentence(ComplexSentence s, ISet <Clause> arg)
{
if (s.IsAndSentence())
{
s.GetSimplerSentence(0).Accept(this, arg);
s.GetSimplerSentence(1).Accept(this, arg);
}
else if (s.IsOrSentence())
{
IList <Literal> literals = new List <Literal>(LiteralCollector.getLiterals(s)); //ArrayList
arg.Add(new Clause(literals));
}
else
{
throw new ArgumentException("Sentence is not in CNF: " + s); //IllegalArgumentException
}
return(arg);
}
public override ISet <Clause> visitBinarySentence(ComplexSentence s, ISet <Clause> arg)
{
if (s.isAndSentence())
{
s.getSimplerSentence(0).accept(this, arg);
s.getSimplerSentence(1).accept(this, arg);
}
else if (s.isOrSentence())
{
ICollection <Literal> literals = CollectionFactory.CreateQueue <Literal>(LiteralCollector.getLiterals(s));
arg.Add(new Clause(literals));
}
else
{
throw new IllegalArgumentException("Sentence is not in CNF: " + s);
}
return(arg);
}
public override Sentence visitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.isImplicationSentence())
{
// Eliminate =>, replacing α => β
// with ~α | β
Sentence alpha = s.getSimplerSentence(0).accept(this, arg);
Sentence beta = s.getSimplerSentence(1).accept(this, arg);
Sentence notAlpha = new ComplexSentence(Connective.NOT, alpha);
result = new ComplexSentence(Connective.OR, notAlpha, beta);
}
else
{
result = base.visitBinarySentence(s, arg);
}
return(result);
}
public override Sentence visitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.isBiconditionalSentence())
{
// Eliminate <=>, replace α <=> β
// with (α => β) & (β => α)
Sentence alpha = s.getSimplerSentence(0).accept(this, arg);
Sentence beta = s.getSimplerSentence(1).accept(this, arg);
Sentence alphaImpliesBeta = new ComplexSentence(
Connective.IMPLICATION, alpha, beta);
Sentence betaImpliesAlpha = new ComplexSentence(
Connective.IMPLICATION, beta, alpha);
result = new ComplexSentence(Connective.AND, alphaImpliesBeta,
betaImpliesAlpha);
}
else
{
result = base.visitBinarySentence(s, arg);
}
return result;
}
public override Sentence VisitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.IsBiconditionalSentence())
{
// Elimina <=>, reemplazando α <=> β con (α => β) & (β => α)
Sentence alpha = s.GetSimplerSentence(0).Accept(this, arg);
Sentence beta = s.GetSimplerSentence(1).Accept(this, arg);
Sentence alphaImpliesBeta = new ComplexSentence(
Connective.IMPLICATION, alpha, beta);
Sentence betaImpliesAlpha = new ComplexSentence(
Connective.IMPLICATION, beta, alpha);
result = new ComplexSentence(Connective.AND, alphaImpliesBeta,
betaImpliesAlpha);
}
else
{
result = base.VisitBinarySentence(s, arg);
}
return(result);
}
public override Sentence VisitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.IsOrSentence())
{
Sentence s1 = s.GetSimplerSentence(0).Accept(this, arg);
Sentence s2 = s.GetSimplerSentence(1).Accept(this, arg);
if (s1.IsAndSentence() || s2.IsAndSentence())
{
Sentence alpha, betaAndGamma;
if (s2.IsAndSentence())
{
// (α | (β & γ))
// Nota: incluso si ambos son sentencias 'and' preferiremos usar s2
alpha = s1;
betaAndGamma = s2;
}
else
{
// Nota: Hace falta manejar este caso también
// ((β & γ) | α)
alpha = s2;
betaAndGamma = s1;
}
Sentence beta = betaAndGamma.GetSimplerSentence(0);
Sentence gamma = betaAndGamma.GetSimplerSentence(1);
if (s2.IsAndSentence())
{
// ((α | β) & (α | γ))
Sentence alphaOrBeta = (new ComplexSentence(Connective.OR,
alpha, beta)).Accept(this, null);
Sentence alphaOrGamma = (new ComplexSentence(Connective.OR,
alpha, gamma)).Accept(this, null);
result = new ComplexSentence(Connective.AND, alphaOrBeta,
alphaOrGamma);
}
else
{
// ((β | α) & (γ | α))
Sentence betaOrAlpha = (new ComplexSentence(Connective.OR,
beta, alpha)).Accept(this, null);
Sentence gammaOrAlpha = (new ComplexSentence(Connective.OR,
gamma, alpha)).Accept(this, null);
result = new ComplexSentence(Connective.AND, betaOrAlpha,
gammaOrAlpha);
}
}
else
{
result = new ComplexSentence(Connective.OR, s1, s2);
}
}
else
{
result = base.VisitBinarySentence(s, arg);
}
return(result);
}
// Es virtual por si hace falta sobreescribirlo
public virtual ISet <T> VisitUnarySentence(ComplexSentence s, ISet <T> arg)
{
return(SetOps.Union(arg, s.GetSimplerSentence(0).Accept(this, arg)));
}
// No hace falta override porque PLVisitor es una interfaz, pero pongo virtual por si queremos seguir sobreescribiendo
public virtual Sentence VisitBinarySentence(ComplexSentence s, A arg)
{
// Una nueva sentencia compleja con la misma conectiva pero posiblemente con sus sentencias más simples reemplazadas por el visitante.
return(new ComplexSentence(s.GetConnective(), s.GetSimplerSentence(0).Accept(this, arg), s.GetSimplerSentence(1).Accept(this, arg)));
}
private ICollection <ParseNode> groupSimplerSentencesByConnective(
Connective connectiveToConstruct, ICollection <ParseNode> parseNodes)
{
ICollection <ParseNode> newParseNodes = CollectionFactory.CreateQueue <ParseNode>();
int numSentencesMade = 0;
// Go right to left in order to make right associative,
// which is a natural default for propositional logic
for (int i = parseNodes.Size() - 1; i >= 0; i--)
{
ParseNode parseNode = parseNodes.Get(i);
if (parseNode.node is Connective)
{
Connective tokenConnective = (Connective)parseNode.node;
if (tokenConnective == Connective.NOT)
{
// A unary connective
if (i + 1 < parseNodes.Size() &&
parseNodes.Get(i + 1).node is Sentence)
{
if (tokenConnective == connectiveToConstruct)
{
ComplexSentence newSentence = new ComplexSentence(
connectiveToConstruct,
(Sentence)parseNodes.Get(i + 1).node);
parseNodes.Set(i, new ParseNode(newSentence, parseNode.token));
parseNodes.Set(i + 1, null);
numSentencesMade++;
}
}
else
{
throw new ParserException(
"Unary connective argurment is not a sentence at input position "
+ parseNode.token
.getStartCharPositionInInput(),
parseNode.token);
}
}
else
{
// A Binary connective
if ((i - 1 >= 0 && parseNodes.Get(i - 1).node is Sentence)
&& (i + 1 < parseNodes.Size() && parseNodes
.Get(i + 1).node is Sentence))
{
// A binary connective
if (tokenConnective == connectiveToConstruct)
{
ComplexSentence newSentence = new ComplexSentence(
connectiveToConstruct,
(Sentence)parseNodes.Get(i - 1).node,
(Sentence)parseNodes.Get(i + 1).node);
parseNodes.Set(i - 1, new ParseNode(newSentence, parseNode.token));
parseNodes.Set(i, null);
parseNodes.Set(i + 1, null);
numSentencesMade++;
}
}
else
{
throw new ParserException("Binary connective argurments are not sentences at input position "
+ parseNode.token
.getStartCharPositionInInput(),
parseNode.token);
}
}
}
}
for (int i = 0; i < parseNodes.Size(); ++i)
{
ParseNode parseNode = parseNodes.Get(i);
if (parseNode != null)
{
newParseNodes.Add(parseNode);
}
}
// Ensure no tokens left unaccounted for in this pass.
int toSubtract = 0;
if (connectiveToConstruct == Connective.NOT)
{
toSubtract = (numSentencesMade * 2) - numSentencesMade;
}
else
{
toSubtract = (numSentencesMade * 3) - numSentencesMade;
}
if (parseNodes.Size() - toSubtract != newParseNodes.Size())
{
throw new ParserException(
"Unable to construct sentence for connective: "
+ connectiveToConstruct + " from: " + parseNodes,
getTokens(parseNodes));
}
return(newParseNodes);
}
protected ISet <Clause> translateToSAT(Describe init, Describe transition, Describe goal, int t)
{
Sentence s = ComplexSentence.newConjunction(init.assertions(t), transition.assertions(t), goal.assertions(t));
return(ConvertToConjunctionOfClauses.convert(s).getClauses());
}
public override Sentence visitBinarySentence(ComplexSentence s, object arg)
{
Sentence result = null;
if (s.isAndSentence())
{
Sentence s1 = s.getSimplerSentence(0).accept(this, arg);
Sentence s2 = s.getSimplerSentence(1).accept(this, arg);
if (s1.isOrSentence() || s2.isOrSentence())
{
Sentence alpha, betaAndGamma;
if (s2.isOrSentence())
{
// (α & (β | γ))
// Note: even if both are 'or' sentence
// we will prefer to use s2
alpha = s1;
betaAndGamma = s2;
}
else
{
// Note: Need to handle this case too
// ((β | γ) & α)
alpha = s2;
betaAndGamma = s1;
}
Sentence beta = betaAndGamma.getSimplerSentence(0);
Sentence gamma = betaAndGamma.getSimplerSentence(1);
if (s2.isOrSentence())
{
// ((α & β) | (α & γ))
Sentence alphaAndBeta = (new ComplexSentence(Connective.AND,
alpha, beta)).accept(this, null);
Sentence alphaAndGamma = (new ComplexSentence(Connective.AND,
alpha, gamma)).accept(this, null);
result = new ComplexSentence(Connective.OR, alphaAndBeta,
alphaAndGamma);
}
else
{
// ((β & α) | (γ & α))
Sentence betaAndAlpha = (new ComplexSentence(Connective.AND,
beta, alpha)).accept(this, null);
Sentence gammaAndAlpha = (new ComplexSentence(Connective.AND,
gamma, alpha)).accept(this, null);
result = new ComplexSentence(Connective.OR, betaAndAlpha,
gammaAndAlpha);
}
}
else
{
result = new ComplexSentence(Connective.AND, s1, s2);
}
}
else
{
result = base.visitBinarySentence(s, arg);
}
return(result);
}
