Input: query , micro-cluster set from materialized
        children cells, bottom-up style cube similarity
         threshold , relative severity threshold
    Output: the significant macro-cluster set sig_set for the query
1      Compute from bu_cube for ;
2      If
3        add to red zone set red_set;
4     end
5     foreach micro-cluster do
6        if intersects with red_set then add to
7 ;
7     end
8 clustering (Algorithm 1)
9 foreach do
10   if then remove ;
11    end
12    return ;
Algorithm 4: Red-zone guided clustering.