Some additional inquiry information . ... Rule of fours . The sequences in alignment can be casual. ... But we can tell, that the more the alignment tries to satisfy the rule of fours, the better it is. ... But, according to the rule of fours, we can take 3 sums of distances between sequences (there are six distances: |AB|, ... The more is the meaning of this parameter, the more exactly the rule or fours is satisfied, and, hence, the better the considered alignment is. ...