| ⊦ j < 0 ∧ 0 < i + j → abs(j) < i |
j < 0, 0 < i + j, ¬ abs(j) < i ⊦
| j < 0, 0 < i + j, ¬ abs(j) < i ⊦ |
Used simplifier rules: abs-08: ⊦ i < 0 → abs(i) = ~ i; Minus-def: ⊦ ~ i = 0 - i; sub-ls: ⊦ i - j < i0 ↔ i < j + i0; forward-le-02: ⊦ j < i ∧ i ≤ 0 → j < 0; forward-le-05: ⊦ i < j ∧ 0 ≤ i → 0 < j; lf-04: ⊦ ¬ j < i ∧ j < i0 → i < i0; (forward) from specification int-basic1 lf-07: ⊦ ¬ i < i0 ∧ j < i0 → j < i; (forward) from specification int-basic1 add-c: ⊦ i + j = j + i; from specification int-basic2 trans: ⊦ i < j ∧ j < j0 → i < j0; (forward) from specification int-basic1 lf-01: ⊦ i < j ∧ j < i0 → i +1 < i0; (forward) from specification int-basic1
The following image shows the proof tree of sequent calculus. The proved goal is at the bottom. You can click on the nodes to view additional rules. See here for details on colors in a proof tree.