anchor.diff:                                  true  -> ordsets:add_element(Lid, Possible);
                                   false -> Possible
                               end,
  -                        ?debug("  Backtrack: ~w\n", [Backtrack]),
  -                        ?debug("  Predecess: ~w\n", [Predecessors]),
  -                        ?debug("  SleepSet : ~w\n", [SleepSet]),
  -                        ?debug("  Initial  : ~w\n", [Initial]),
  +                        ?debug("  Backtrack: ~p\n", [Backtrack]),
  +                        ?debug("  Predecess: ~p\n", [Predecessors]),
  +                        ?debug("  SleepSet : ~p\n", [SleepSet]),
  +                        ?debug("  Initial  : ~p\n", [Initial]),
                           case concuerror_lid:deep_intersect_with_fix(Backtrack,
                                                                       Initial) of
                               {true, NewBacktrack} ->
  
positive.code:                                         NewBacktrack =
                                              concuerror_lid:insert_to_deep_list(
                                                Backtrack, Predecessors),
                                          ?debug("     Add: ~w (~w)\n",
                                                   [Predecessors, NewBacktrack]),
                                          NewPreSI =
                                              PreSI#trace_state{
  
negative.code:                 end;
              Else -> [Else]
          end,
      ?debug("Picked: ~p\n",[Choice]),
      Backtrack = concuerror_lid:make_backtrack(Choice),
      NewTraceTop = TraceTop#trace_state{backtrack = Backtrack},
      State#dpor_state{trace = [NewTraceTop|Rest]}.
  