docs: private int maxIntersection(Map<Integer, ModifiableDBIDs> candidates, ModifiableDBIDs set) {
      int maxDim = -1;
      ModifiableDBIDs maxIntersection = null;
      for(Integer nextDim : candidates.keySet()) {
        DBIDs nextSet = candidates.get(nextDim);
        ModifiableDBIDs nextIntersection = DBIDUtil.intersection(set, nextSet);
        if(maxDim < 0 || maxIntersection.size() < nextIntersection.size()) {
          maxIntersection = nextIntersection;
          maxDim = nextDim;
        }
      }
      if(maxDim >= 0) {
        set.clear();
        set.addDBIDs(maxIntersection);
      }
      return maxDim;
    }