| 0 < i1, 0 < j1, i < i1, j < j1, i1 * j ≤ i * j, 0 ≤ i, 0 ≤ j, 0 ≤ i1, 0 ≤ j1, i1 * j1 ≤ i * j ⊦ i * j < i * j1 |
j < j1, i < i1, 0 < j1, 0 < i1, i1 * j1 ≤ i * j, 0 ≤ j1, 0 ≤ i1, 0 ≤ j, 0 ≤ i, i1 * j ≤ i * j, i * j1 ≤ i * j ⊦
Used simplifier rules: ⊦ i < j ↔ ¬ j ≤ i; (ss)