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