anchor.diff:  
   -spec normalize_internal([simple_interval()]) -> interval(). % for dialyzer
   normalize_internal(List) ->
  -    NormalizedList1 = lists:flatmap(fun(I) -> normalize_simple(I) end, List),
  +    NormalizedList1 = lists:flatmap(fun normalize_simple/1, List),
       merge_adjacent(lists:usort(fun interval_sort/2, NormalizedList1), []).
   
   %% @doc Normalizes simple intervals (see normalize_internal/1).
  
positive.code: -module(intervals).
  -author('schuett@zib.de').
  -vsn('$Id$').
  
  -include("scalaris.hrl").
  
  
negative.code: minus(_A, [all]) -> empty();
  minus(A, [])     -> A;
  minus(A, A)      -> empty();
  minus(A, [HB | TB]) ->
      % from every simple interval in A, remove all simple intervals in B
      % note: we cannot use minus_simple in foldl since the result may be a list again
      normalize_internal(lists:flatten([minus(minus_simple(IA, HB), TB) || IA <- A])).
  
  %% @private
  %% @doc Determines whether an interval with the given borders wraps around,
  