U, U n > m > k > 0 , U n > m > k k > 0 , U n > m m > k k > 0 , U n > m m > k k > 0 n, m, k

U, 2s U k=1 , 2s U m, n=1 , 2s U m=1 n=1 , 2s U k=1 m=1 n=1 , 2s U k=1 m=1 n=1 enough

Base, Base under , over Base , over Base under I under II , Base under I under II under III , over Base under