| 1 ≤ j ∧ j ≤ i → (binom_coef(i, j) - binom_coef(i, j - 1)) * fac(j) * fac(i + 1 - j) = fac(i) * (i + 1 - 2 * j), j ≤ i, 0 < j, 0 < i ⊦ binom_coef(i, j) = (fac(i) * (i + 1 - 2 * j)) / (fac(j) * fac(i + 1 - j)) + binom_coef(i, j - 1) |
(binom_coef(i, j) - binom_coef(i, j - 1)) * fac(j) * fac(i + 1 - j) = fac(i) * (i + 1 - 2 * j), j ≤ i, 0 < j, 0 < i ⊦ binom_coef(i, j) = (fac(i) * (i + 1 - 2 * j)) / (fac(j) * fac(i + 1 - j)) + binom_coef(i, j - 1)
Used simplifier rules: leone: ⊦ 1 ≤ i ↔ 0 < i; from specification int-abs