| 1 + # x0 = n0 + m0, ∀ n0, m0. # x0 = n0 + m0 → firstn(m0, x0) + firstn(n0, restn(m0, x0)) = x0 ⊦ ((a ' + x0).head ' + firstn(m0 -1, (a ' + x0).tail)) + firstn(n0, restn(m0, a ' + x0)) = a ' + x0, m0 = 0 |
1 + # x0 = n0 + m0, ∀ n0, m0. # x0 = n0 + m0 → firstn(m0, x0) + firstn(n0, restn(m0, x0)) = x0 ⊦ firstn(m0 - 1, x0) + firstn(n0, restn(m0, a ' + x0)) = x0, m0 = 0
Used simplifier rules: ⊦ x + y = x + z ↔ y = z; (s)% ⊦ (a ' + x).tail = x; (s)% ⊦ n -1 = n - 1; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ (a ' + x).head = a; (s)