| ⊦ i ≤ 0 ∧ j ≤ 0 → (abs(i) < abs(j) ↔ j < i) |
¬(abs(i) < abs(j) ↔ j < i), i ≤ 0, j ≤ 0 ⊦
| ¬(abs(i) < abs(j) ↔ j < i), i ≤ 0, j ≤ 0 ⊦ |
¬(abs(i) < abs(j) ↔ j < i), ¬ 0 < j, ¬ 0 < i ⊦
Used simplifier rules: le-def: ⊦ i ≤ j ↔ ¬ j < i;
| ¬(abs(i) < abs(j) ↔ j < i), ¬ 0 < j, ¬ 0 < i ⊦ |
¬(abs(i) < abs(j) ↔ j < i), i < 0, ¬ 0 < j, ¬ 0 < i ⊦
Used simplifier rules: Abs-pos: ⊦ ¬ j < 0 → abs(j) = j; abs-08: ⊦ i < 0 → abs(i) = ~ i; Minus-def: ⊦ ~ i = 0 - i; sub-ls-01: ⊦ i < j - i0 ↔ i + i0 < j; zero-gels-01: ⊦ i < 0 ∧ 0 ≤ j → i < j; ⊦ ¬ i < j → (j < i ↔ i ≠ j); (ss) ⊦ 0 + i = i; (s) add-a: ⊦ i + j + i0 = (i + j) + i0; from specification int-basic2 add-c: ⊦ i + j = j + i; from specification int-basic2 Used formulas: i < 0
| ¬(abs(i) < abs(j) ↔ j < i), i < 0, ¬ 0 < j, ¬ 0 < i ⊦ |
¬(0 < i + abs(j) ↔ j < i), i < 0, ¬ 0 < j ⊦
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; zero-gels-01: ⊦ i < 0 ∧ 0 ≤ j → i < j; ⊦ i < j → ¬ j < i; (s)
| ¬(0 < i + abs(j) ↔ j < i), i < 0, ¬ 0 < j ⊦ |
Used simplifier rules: abs-08: ⊦ i < 0 → abs(i) = ~ i; Minus-def: ⊦ ~ i = 0 - i; sub-zero: ⊦ i + (0 - i0) = i - i0; sub-ls-01: ⊦ i < j - i0 ↔ i + i0 < j; Abs-pos: ⊦ ¬ j < 0 → abs(j) = j; forward-le-05: ⊦ i < j ∧ 0 ≤ i → 0 < j; ⊦ i < j ∧ ¬ i0 < j → ¬ i0 < i; (s) ⊦ ¬ i < j → (j < i ↔ i ≠ j); (ss) lf-01: ⊦ i < j ∧ j < i0 → i +1 < i0; (forward) from specification int-basic1 trans: ⊦ i < j ∧ j < j0 → i < j0; (forward) from specification int-basic1 lf-02: ⊦ i < j ∧ j = i0 → i < i0; (forward) from specification int-basic1 lf-04: ⊦ ¬ j < i ∧ j < i0 → i < i0; (forward) from specification int-basic1 ⊦ 0 + i = i; (s) add-a: ⊦ i + j + i0 = (i + j) + i0; from specification int-basic2 add-c: ⊦ i + j = j + i; from specification int-basic2 ⊦ i < j → ¬ j < i; (s) Used formulas: j < 0
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.