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