/**
* 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);
}