public object visitConnectedSentence(ConnectedSentence sentence, object arg)
{
ArgData ad = (ArgData)arg;
Sentence first = sentence.getFirst();
Sentence second = sentence.getSecond();
first.accept(this, arg);
if (Connectors.isAND(sentence.getConnector()))
{
ad.clauses.Add(new Clause());
}
second.accept(this, arg);
return(sentence);
}
public object visitConnectedSentence(ConnectedSentence sentence, object arg)
{
// Distribute V over ^:
// This will cause flattening out of nested ^s and Vs
Sentence alpha = (Sentence)sentence.getFirst().accept(this, arg);
Sentence beta = (Sentence)sentence.getSecond().accept(this, arg);
// (alpha V (beta ^ gamma)) equivalent to
// ((alpha V beta) ^ (alpha V gamma))
if (Connectors.isOR(sentence.getConnector()) &&
beta is ConnectedSentence)
{
ConnectedSentence betaAndGamma = (ConnectedSentence)beta;
if (Connectors.isAND(betaAndGamma.getConnector()))
{
beta = betaAndGamma.getFirst();
Sentence gamma = betaAndGamma.getSecond();
return(new ConnectedSentence(Connectors.AND,
(Sentence)(new ConnectedSentence(Connectors.OR, alpha, beta)).accept(this, arg),
(Sentence)(new ConnectedSentence(Connectors.OR, alpha, gamma)).accept(this, arg)));
}
}
// ((alpha ^ gamma) V beta) equivalent to
// ((alpha V beta) ^ (gamma V beta))
if (Connectors.isOR(sentence.getConnector()) &&
alpha is ConnectedSentence)
{
ConnectedSentence alphaAndGamma = (ConnectedSentence)alpha;
if (Connectors.isAND(alphaAndGamma.getConnector()))
{
alpha = alphaAndGamma.getFirst();
Sentence gamma = alphaAndGamma.getSecond();
return(new ConnectedSentence(Connectors.AND,
(Sentence)(new ConnectedSentence(Connectors.OR, alpha,
beta)).accept(this, arg),
(Sentence)(new ConnectedSentence(Connectors.OR, gamma,
beta)).accept(this, arg)));
}
}
return(new ConnectedSentence(sentence.getConnector(), alpha, beta));
}
public object visitConnectedSentence(ConnectedSentence sentence, object arg)
{
Sentence alpha = (Sentence)sentence.getFirst().accept(this, arg);
Sentence beta = (Sentence)sentence.getSecond().accept(this, arg);
// Eliminate <=>, bi-conditional elimination,
// replace (alpha <=> beta) with (~alpha V beta) ^ (alpha V ~beta).
if (Connectors.isBICOND(sentence.getConnector()))
{
Sentence first = new ConnectedSentence(Connectors.OR, new NotSentence(alpha), beta);
Sentence second = new ConnectedSentence(Connectors.OR, alpha, new NotSentence(beta));
return(new ConnectedSentence(Connectors.AND, first, second));
}
// Eliminate =>, implication elimination,
// replacing (alpha => beta) with (~alpha V beta)
if (Connectors.isIMPLIES(sentence.getConnector()))
{
return(new ConnectedSentence(Connectors.OR, new NotSentence(alpha), beta));
}
return(new ConnectedSentence(sentence.getConnector(), alpha, beta));
}