⊦ 0 < i → (i * j ≤ i * i0 ↔ j ≤ i0)
0 < i, 0 < i → (i * j ≤ i * 0 ↔ j ≤ 0) ⊦ i * j ≤ 0 ↔ j ≤ 0
Used terms: i, j, 0