/// <summary>
/// Splits the tree into a branch containing clauses where P appears and another branch with clauses where Not(p) appears.
/// </summary>
/// <param name="cnf"></param>
/// <returns>Returns a Tuple with two CnFs one for the first branch and another for the second branch.</returns>
private Tuple <Cnf, Cnf> Split(Cnf cnf)
{
var literal = Heuristics.ChooseLiteral(cnf);
if (literal == null)
{
return(new Tuple <Cnf, Cnf>(new Cnf(), new Cnf()));
}
var tuple = SplittingOnLiteral(cnf, literal);
return(new Tuple <Cnf, Cnf>(RemoveLiteral(tuple.Item1, literal), RemoveLiteral(tuple.Item2, NegateLiteral(literal))));
}
