i ≤ i0 ⊦ i + j0 ≤ i0 ∧ j0 ≥ 0 → i ≤ i0 + j0
Used simplifier rules: le-def: ⊦ i ≤ j ↔ ¬ j < i;%ge-def: ⊦ i ≥ j ↔ ¬ i < j;