| (i + 1 - j) * fac(i - j) * fac(j - 1) | fac(i), 0 ≤ j, 0 ≤ i, j ≤ i, 0 < i, 0 < j, fac(i - j) * j * fac(j - 1) | fac(i) ⊦ (i + 1 - j) * fac(i - j) = (j + i + 1 - 2 * j) * fac(i - j) |
⊦ i ≠ 0 → (j * i = j0 * i ↔ j = j0)
Used simplifier rules: fac-zero-02: ⊦ fac(i) ≠ 0;%sub-eq: ⊦ i - j = i0 ↔ i = i0 + j; from specification int-abs%sub-add-01: ⊦ i + (j - i0) = i + j - i0; from specification int-abs%add-mult-two: ⊦ i + i = 2 * i; from specification int-mult%add-a: ⊦ i + j + i0 = (i + j) + i0; from specification int-basic2%add-c: ⊦ i + j = j + i; from specification int-basic2%sub-add: ⊦ i + j - i = j; from specification int-abs%add-in: ⊦ i + j = i + i0 ↔ j = i0; from specification int-basic2 Used terms: j + i + 1 - 2 * j, fac(i - j), i + 1 - j