0 < i, 0 < j, i ≤ i0, j < j0 ⊦ i * j < i0 * j0
⊦ 0 < 1 ∧ 0 < 1 ∧ 1 ≤ i ∧ 1 < j, i * j = 1 ↔ abs(j) = 1 ∧ i = j
1 * 1 < i * j ⊦ i * j = 1 ↔ abs(j) = 1 ∧ i = j
Used terms: 1, 1, i, j