anchor.diff:      for v in innerGraph.Vertices do
           outEdgesInnerGraph.[v.vNum] <- innerGraph.OutEdges v |> Array.ofSeq
       let gssVertexesToPrefixes = new Dictionary<_,_>()
  -    let vertexesToPrefixes = new Dictionary<_,_>()
  -    for v in innerGraph.Vertices do
  -        vertexesToPrefixes.Add(v, new ResizeArray<Prefix<'TokenType>>())
  -    let edgesToPrefixes = new Dictionary<_,ResizeArray<Prefix<'TokenType>>>()
  +    let passedPrefixes = new Dictionary<_,ResizeArray<Prefix<'TokenType>>>()
  +    let notPassedPrefixes = new Dictionary<_,ResizeArray<Prefix<'TokenType>>>()
       for v in innerGraph.Vertices do
           for e in outEdgesInnerGraph.[v.vNum] do
  -            edgesToPrefixes.Add(e, new ResizeArray<Prefix<'TokenType>>())
  +            passedPrefixes.Add(e, new ResizeArray<Prefix<'TokenType>>())
  +            notPassedPrefixes.Add(e, new ResizeArray<Prefix<'TokenType>>())
       let errorEdges = new Dictionary<QuickGraph.TaggedEdge<_,_>,_>()
       
       let drawDot (tokenToNumber : _ -> int) (tokens : BlockResizeArray<_>) (leftSide : int[])
  
positive.code:             graphV.passingReductions.Remove((v, e)) |> ignore
  
      let checkEdges (v:VInfo<_>) =
          for e in edgesToPrefixes.Keys do
              if e.Source.vNum = v.vNum
              then
                  let passedPrefixes = edgesToPrefixes.[e]
                  for vertexPrefix in vertexesToPrefixes.[v] do
                      if not <| passedPrefixes.Contains(vertexPrefix)
                      then
                          if not <| errorEdges.ContainsKey(e)
                          then errorEdges.Add(e, new ResizeArray<Prefix<'TokenType>>())
                          addPrefix errorEdges.[e] vertexPrefix
  
      let buildErrors (errdict:Dictionary<QuickGraph.TaggedEdge<_,_>,ResizeArray<Prefix<'TokenType>>>) =
          let outErrors = new Dictionary<string,ResizeArray<Prefix<'TokenType>>>()
  
negative.code:         let prefixes = gssVertexesToPrefixes.[newVertex]
          for prefixToAdd in prefixesToAdd do
              addPrefix prefixes prefixToAdd //add new prefix to gss vertex
  
          if isNotEps
          then
  