anchor.diff:              IM, IMNew, IMNew - IM,
               CM, CMNew, CMNew - CM]),
       %clean up
  -    ?assert(CM =:= 0) andalso ?assert(CMNew > CM).
  +    ?equals(CM, 0),
  +    ?compare(fun erlang:'>'/2, CMNew, CM).
   
   parts(Config) ->
       Method = proplists:get_value(ru_method, Config),
  
positive.code: 
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  
  -spec prop_get_key_quadrant(?RT:key()) -> boolean().
  prop_get_key_quadrant(Key) ->
      Q = rr_recon:get_key_quadrant(Key),
      QI = intervals:split(intervals:all(), 4),
  
negative.code:     SizeSA = rr_recon:get_interval_size(SA),
      SizeSB = rr_recon:get_interval_size(SB),
      ?implies(A =/= B, SA =/= SB) andalso
          ?equals(rr_recon:find_intersection(A, A), A) andalso
          ?equals(rr_recon:find_intersection(B, B), B) andalso
          ?implies(intervals:is_subset(B, A), SB =:= SA) andalso
          ?implies(intervals:is_subset(A, B), SB =:= SA) andalso
          ?assert(intervals:is_subset(SA, A)) andalso
  