| 0 < j, abs(i) * j < j, abs(i) ≤ i1, abs(i) * j ≤ 0, ∀ j0, i0. 0 < j0 ∧ i0 ≠ 0 ∧ abs(i0) < i1 → 0 < abs(i0) * j0 ⊦ i = 0 |
⊦ ¬ j < 0 → abs(j) = j
i < 0, abs(i) * j < j, 0 < j, abs(i) * j ≤ 0, abs(i) ≤ i1, ∀ j0, i0. 0 < j0 ∧ i0 ≠ 0 ∧ abs(i0) < i1 → 0 < abs(i0) * j0 ⊦ i = 0
i * j < j, 0 < j, i * j ≤ 0, i ≤ i1, ∀ j0, i0. 0 < j0 ∧ i0 ≠ 0 ∧ abs(i0) < i1 → 0 < abs(i0) * j0 ⊦ i = 0, i < 0
Used terms: i