“…For example, the evaluation value of the correlation degree of DR2 relative to DR8 in the four design characteristics is {6, 6, 9, 5} and converted into rough values is { [5,6], [5,6], [8,9], [4,5]}. Then, the element c 28 = ( [5,6] + [5,6] + [8,9] + [4,5])/4 = [3,4].…”