public override BooleanExpression ToNNF()
{
if (InnerExpression is Negation neg)
{
return(neg.InnerExpression.ToNNF());
}
else if (InnerExpression is NAryOperator nary)
{
List <BooleanExpression> newOperands = nary.GetOperands().Select(op => new Negation(op).ToNNF()).ToList();
if (nary is Disjunction)
{
return(new Conjunction(newOperands));
}
else // nary is Conjunction
{
return(new Disjunction(newOperands));
}
}
else if (InnerExpression.Equals(FALSE))
{
return(TRUE);
}
else if (InnerExpression.Equals(TRUE))
{
return(FALSE);
}
else
{
return(new Negation(this.InnerExpression.Simplify()));
}
}
