public override Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg) {
Dictionary<Variable, Term> substitution = (Dictionary<Variable, Term>)arg;
Sentence quantified = sentence.getQuantified();
Sentence quantifiedAfterSubs = (Sentence) quantified.accept(this, arg);
List<Variable> variables = new List<Variable>();
foreach (Variable v in sentence.getVariables()) {
if (substitution.ContainsKey(v)) {
Term st = substitution[v];
if (st is Variable) {
// Only if it is a variable to I replace it, otherwise
// I drop it.
variables.Add((Variable) st.copy());
}
} else {
// No substitution for the quantified variable, so
// keep it.
variables.Add((Variable)v.copy());
}
}
// If not variables remaining on the quantifier, then drop it
if (variables.Count == 0) {
return quantifiedAfterSubs;
}
return new QuantifiedSentence(sentence.getQuantifier(), variables,
quantifiedAfterSubs);
}
public Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
// Ensure I collect quantified variables too
List<Variable> variables = (List<Variable>)arg;
variables.AddRange(sentence.getVariables());
sentence.getQuantified().accept(this, arg);
return sentence;
}
public virtual Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
List<Variable> variables = new List<Variable>();
foreach (Variable var in sentence.getVariables())
{
variables.Add((Variable)var.accept(this, arg));
}
return new QuantifiedSentence(sentence.getQuantifier(), variables,
(Sentence)sentence.getQuantified().accept(this, arg));
}
public Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
sentence.getQuantified().accept(this, arg);
return arg;
}
public Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
Sentence quantified = sentence.getQuantified();
List<Variable> universalScope = (List<Variable>)arg;
// Skolemize: Skolemization is the process of removing existential
// quantifiers by elimination. This is done by introducing Skolem
// functions. The general rule is that the arguments of the Skolem
// function are all the universally quantified variables in whose
// scope the existential quantifier appears.
if (Quantifiers.isEXISTS(sentence.getQuantifier()))
{
Dictionary<Variable, Term> skolemSubst = new Dictionary<Variable, Term>();
foreach (Variable eVar in sentence.getVariables())
{
if (universalScope.Count > 0)
{
// Replace with a Skolem Function
String skolemFunctionName = parser.getFOLDomain()
.addSkolemFunction();
skolemSubst.Add(eVar, new Function(skolemFunctionName,
new List<Term>(universalScope)));
}
else
{
// Replace with a Skolem Constant
String skolemConstantName = parser.getFOLDomain()
.addSkolemConstant();
skolemSubst.Add(eVar, new Constant(skolemConstantName));
}
}
Sentence skolemized = substVisitor.subst(skolemSubst, quantified);
return skolemized.accept(this, arg);
}
// Drop universal quantifiers.
if (Quantifiers.isFORALL(sentence.getQuantifier()))
{
// Add to the universal scope so that
// existential skolemization may be done correctly
universalScope.AddRange(sentence.getVariables());
Sentence droppedUniversal = (Sentence)quantified.accept(this, arg);
// Enusre my scope is removed before moving back up
// the call stack when returning
foreach (Variable s in sentence.getVariables())
{
universalScope.Remove(s);
}
return droppedUniversal;
}
// Should not reach here as have already
// handled the two quantifiers.
throw new ApplicationException("Unhandled Quantifier:"
+ sentence.getQuantifier());
}
public Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
List<Variable> seenSoFar = (List<Variable>)arg;
// Keep track of what I have to subst locally and
// what my renamed variables will be.
Dictionary<Variable, Term> localSubst = new Dictionary<Variable, Term>();
List<Variable> replVariables = new List<Variable>();
foreach (Variable v in sentence.getVariables())
{
// If local variable has be renamed already
// then I need to come up with own name
if (seenSoFar.Contains(v))
{
Variable sV = new Variable(quantifiedIndexical.getPrefix()
+ quantifiedIndexical.getNextIndex());
localSubst.Add(v, sV);
// Replacement variables should contain new name for variable
replVariables.Add(sV);
}
else
{
// Not already replaced, this name is good
replVariables.Add(v);
}
}
// Apply the local subst
Sentence subst = substVisitor.subst(localSubst, sentence
.getQuantified());
// Ensure all my existing and replaced variable
// names are tracked
seenSoFar.AddRange(replVariables);
Sentence sQuantified = (Sentence)subst.accept(this, arg);
return new QuantifiedSentence(sentence.getQuantifier(), replVariables,
sQuantified);
}
public Object visitQuantifiedSentence(QuantifiedSentence sentence,
Object arg)
{
return new QuantifiedSentence(sentence.getQuantifier(), sentence
.getVariables(), (Sentence)sentence.getQuantified().accept(
this, arg));
}
