anchor.diff:          
           let rulesHolder = new RulesHolder(crl_result, srl_result, erl_result)
   
  -        recognizeGraph graph squareMatrix rulesHolder nonterminals S
  +        recognizeGraph graph squareMatrix rulesHolder nonterminals !S
  
positive.code: 
          for module' in grammar do
              for r in module'.rules do
                  let nonterm = NonTerminal <| Source.toString r.name           //is this nonterm name?
                  match r.body with
                  | PSeq([elem],_,_) ->
                      match elem.rule with
  
negative.code:                     match e1.rule, e2.rule with 
                      | PRef (name1, _), PRef (name2, _) ->
                          let nonterm1 = NonTerminal <| Source.toString name1
                          if not <| nonterminals.Contains nonterm1
                          then
                              nonterminals.Add nonterm1
                          let nonterm2 = NonTerminal <| Source.toString name2
                          if not <| nonterminals.Contains nonterm2
                          then
                              nonterminals.Add nonterm2
                          if not <| crl.ContainsKey (nonterm1, nonterm2)
                          then
                              crl.Add((nonterm1, nonterm2), new ResizeArray<NonTerminal*Probability.T>())
  