The search starts from the principal diagonal
which is traversed in the “southeast” direction, then goes to
the diagonal above the main diagonal, and so on. During the
iterative search process, this method maintains a top-k list
and an item pair is sorted-inserted into this list if the correlation
coefficient of this item pair is greater than the minimum
correlation coefficient in the top-k list. The search stops if
the maximal upper bound of all item pairs in a diagonal is
less than the current minimum correlation coefficient in the
top-k list.