static Comparator<S> ai_smallerCategoryComparator() {
  final Set<Pair<S>> set = new HashSet(pairsToLower(ai_texts_unquoteBoth("is a smaller category than"))));
  ret new Comparator<S>() {
    public int compare(S a, S b) {
      a = lower(a);
      b = lower(b);
      if (set.contains(pair(a, b))) ret -1;
      if (set.contains(pair(b, a))) ret 1;
      ret 0;
    }
  };
}