public void testIsEmpty()
{
Chain c = new Chain();
Assert.IsTrue(c.isEmpty());
c.addLiteral(new Literal(new Predicate("P", new List<Term>())));
Assert.IsFalse(c.isEmpty());
List<Literal> lits = new List<Literal>();
lits.Add(new Literal(new Predicate("P", new List<Term>())));
c = new Chain(lits);
Assert.IsFalse(c.isEmpty());
}