0 ≤ j ⊦ # int2bits(j) = # int2bits(j + 1), ∃ i. 2 ^ i = j + 1
Used simplifier rules: ⊦ i ≤ j ∧ 0 ≤ i → 0 ≤ j; (forward)% ⊦ i - j = i0 ↔ i = i0 + j;