public void setUp()
{
parser = new PEParser();
trueSentence = (Sentence)parser.parse("true");
falseSentence = (Sentence)parser.parse("false");
andSentence = (Sentence)parser.parse("(P AND Q)");
orSentence = (Sentence)parser.parse("(P OR Q)");
impliedSentence = (Sentence)parser.parse("(P => Q)");
biConditionalSentence = (Sentence)parser.parse("(P <=> Q)");
m = new Model();
}