anchor.diff:          not IsDisjoint ->
               {W1, S1, E1, N1} = Mbr1,
               {W2, S2, E2, N2} = Mbr2,
  -            {max(W1, W2), max(S1, S2), min(E1, E2), min(N1, N2)};
  +            {erlang:max(W1, W2), erlang:max(S1, S2),
  +             erlang:min(E1, E2), erlang:min(N1, N2)};
           true ->
               {0, 0, 0, 0}
       end.
  
positive.code:     MbrE = calc_nodes_mbr(PartE),
      MbrS = calc_nodes_mbr(PartS),
      MbrN = calc_nodes_mbr(PartN),
      MaxWE = max(length(PartW), length(PartE)),
      MaxSN = max(length(PartS), length(PartN)),
      if
          MaxWE < MaxSN ->
              [{MbrW, PartW}, {MbrE, PartE}];
  
negative.code: merge_mbr(Mbr1, Mbr2) ->
      {W1, S1, E1, N1} = Mbr1,
      {W2, S2, E2, N2} = Mbr2,
      {erlang:min(W1, W2), erlang:min(S1, S2),
       erlang:max(E1, E2), erlang:max(N1, N2)}.
  
  
  find_area_min_nth([H|T]) ->
  