Suppose S = {vi} and T = {ti} are "easy" sets of knapsak weight. Also, P and q are primes p > ?Si and q > ?ti. We can combine S and T into a signle set of knapsack weight as follows:
W = qs ? pT = {wi}= {qvi+pti}. Show:1- all sums of the form ?eiwi are distinct. (ei= 0,1)2- W is also an "easy" knapsack, that is solving ?eivi = n can be easily to solving ?eiwi= n1 and ?eiti= n2.