| n1 + m0 < # x, n0 < n1, ∀ n1, m0, x. n1 + m0 < # x ∧ n0 ≤ n1 → x = [] ∨ firstn(n0, restn(m0, x).rest) ⊑ firstn(n1, restn(m0, x).rest) ⊦ x = [], n1 = 0, restn(m0, x).rest.first ' + firstn(n0, restn(m0, x).rest.rest) ⊑ firstn(n1, restn(m0, x).rest) |
n ≠ 0 ⊦ firstn((* n), x) = x.first ' + firstn(n -1, x.rest)
n1 ≠ 0, n1 + m0 < # x, n0 < n1, ∀ n1, m0, x. n1 + m0 < # x ∧ n0 ≤ n1 → x = [] ∨ firstn(n0, restn(m0, x).rest) ⊑ firstn(n1, restn(m0, x).rest) ⊦ x = [], n1 = 0, restn(m0, x).rest.first ' + firstn(n0, restn(m0, x).rest.rest) ⊑ restn(m0, x).rest.first ' + firstn(n1 -1, restn(m0, x).rest.rest)
Used terms: restn(m0, x).rest, n1