/**
* Move ~ inwards.
*
* @param sentence
* a propositional logic sentence that has had it biconditionals
* and implications removed.
* @return an equivalent Sentence to the input with all negations moved
* inwards.
* @throws IllegalArgumentException
* if a biconditional or implication is encountered in the
* input.
*/
public static Sentence moveNotsInward(Sentence sentence)
{
Sentence result = null;
MoveNotInwards moveNotsIn = new MoveNotInwards();
result = sentence.accept(moveNotsIn, null);
return(result);
}
/**
* Returns the specified sentence in its logically equivalent negation
* normal form.
*
* @param s
* a propositional logic sentence
*
* @return the input sentence converted to it logically equivalent
* negation normal form.
*/
public static Sentence convert(Sentence s)
{
Sentence result = null;
Sentence biconditionalsRemoved = BiconditionalElimination.eliminate(s);
Sentence implicationsRemoved = ImplicationElimination.eliminate(biconditionalsRemoved);
Sentence notsMovedIn = MoveNotInwards.moveNotsInward(implicationsRemoved);
result = notsMovedIn;
return(result);
}