2 ^ i = 2 ^ j, 0 ≤ i, 0 ≤ j ⊦ i = j
Used simplifier rules: ⊦ ~1 < i ↔ 0 ≤ i; (s)%numlef-01: ⊦ (* i) ≤ j → i - 1 < j; (forward) from specification int-abs