⊦ i < j ∧ j < j0 → i < j0
j < i ∧ i < i + i1 → j < i + i1, i1 < i + i1, 0 < i, j < i, 0 < j, 1 < i, 0 < i1 ⊦ j < i + i1
Used terms: j, i, i + i1