| n + n0 + n1 ≤ 1 + # x0, ∀ n, n0, n1. n + n0 + n1 ≤ # x0 → firstn(n0, restn(n, x0)) + firstn(n1, restn(n + n0, x0)) = firstn(n0 + n1, restn(n, x0)) ⊦ firstn(n0, restn(n, a ' + x0)) + firstn(n1, restn(n + n0, a ' + x0)) = firstn(n0 + n1, restn(n, a ' + x0)), 0 < n |
n0 + n1 ≤ 1 + # x0, ∀ n, n0, n1. n + n0 + n1 ≤ # x0 → firstn(n0, restn(n, x0)) + firstn(n1, restn(n + n0, x0)) = firstn(n0 + n1, restn(n, x0)) ⊦ firstn(n0, a ' + x0) + firstn(n1, restn(n0, a ' + x0)) = firstn(n0 + n1, a ' + x0)
Used simplifier rules: restN-zero: ⊦ restn(0, x) = x;%c: ⊦ m + n = n + m; from specification nat-basic%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic% ⊦ 0 + m = m; (s)% ⊦ 0 < m ↔ m ≠ 0; (s)