j < 0 ⊦ ¬ 2 ^ (n→i(# int2bits(j)) - 1) + j < 0, # int2bits(j) = 1
j < 0 ⊦ ¬ 0 ≤ j + 2 ^ (n→i(# int2bits(j)) - 2), # int2bits(j) = 1