i + j1 < j + j0, i + i0 < j + j0, j0 < j1, i1 < i0 ⊦ i + i1 < j + j1
i + i0 < j + j0, j0 < j1, i1 < i0 ⊦ i + j1 < j + j0, i + i1 < j + j1
Used formulas: i + j1 < j + j0