public bool IsInCNF()
{
return(rules.All(r =>
{
return r.Value.All(rs =>
{
switch (rs.Count())
{
case 1: return TS.IsSupersetOf(rs.Symbols);
case 2: return NTS.IsSupersetOf(rs.Symbols);
default: return false;
}
}) && (r.Key.Symbols[0].Equals(S) || r.Value.All(rs => !rs.Contains("")));
}));
}