# this is also called 'edit distance'. # consider sequence X = (x1,x2,..,xm) and Y=(y1,y2, ..., yn); # an alignment is a subset A belongs to {1,...,m} * {1, .., n} # for any (i,j) and (i',j'): i != i', j!= j', i < i' -> j<j' # cost function: the number of unmatched pairs + sum(matching valu...