anchor.diff:  %%------------------------------------------------------------------------------
   lookup(_, []) ->
     [];
  +lookup({Xi,K}, [{node,{Xi,K,{i,V,_}},SNs}|DTree]) ->
  +  %%----------------------------------------------------------------------------
  +  %% If during our search we reach a context which is exactly the same as the 
  +  %% one we are looking for, we know we have found the result.
  +  %%------------------------------------------------------------------------------
  +  V;
   lookup({Xi,K}, [{node,{Xi,K,V},SNs}|DTree]) ->
     %%----------------------------------------------------------------------------
     %% If during our search we reach a context which is exactly the same as the 
  
positive.code:   lookup({"B", []}, test_data_2()),
    lookup({"B", [{s, 0}]}, test_data_2()),
    lookup({"B", [{t, 0}, {s, 0}]}, test_data_2()),
    
    DT1 = insert({"A",[],{i,[t],[]}},[]),
    DT2 = insert({"A",[{t,1}],{i,[s],[]}}, DT1),
    DT3 = insert({"A", [{t,1},{s,0}], {calc, [0]}}, DT2),
    DT4 = insert({"A", [{t,1},{s,0}], 2}, DT3),
    DT5 = insert({"A", [{t,0}], {i, [s], []}}, DT4),
    DT6 = insert({"A", [{t,0},{s,0}], 1}, DT5),
    DT7 = insert({"A", [{t,0},{s,1}], 1}, DT6),
    DT7.
    
    
    
  
negative.code:   %%----------------------------------------------------------------------------
    NewTree ++ [{node,{Xi,K,V},SNs}|DTree];
  insert({Xi,K0,V}, [{node,{Xi,K1,{i,Dims,Ords}},SNs}=Node|DTree], NewTree) ->
    %%----------------------------------------------------------------------------
    %% If the context of the node we want to insert is a subset of the context
    %% we are searching for, and the ordinate for this dimension is not known, 
    %% we need to update the known ordinates of this internal node and continue 
    %% the insertion.
    %% If the ordinate is known, we continue the insertion to update the value.
    %%----------------------------------------------------------------------------
    case tset:intersection(K0, K1) of
      K1 ->
        case lists:any(fun (X) ->
  