| n0 + 1 < # x, ∀ x. n0 < # x → x = firstn(n0, x) + restn(n0, x) ∨ x = [] ⊦ x = [], x = (x.first ' + firstn(n0, x.rest)) + restn(n0, x.rest) |
x = a + y, n0 + 1 < # x, ∀ x. n0 < # x → x = firstn(n0, x) + restn(n0, x) ∨ x = [] ⊦ x = [], x = (a ' + firstn(n0, y)) + restn(n0, y)
Used simplifier rules: x ≠ [] ⊦ a = x.first ∧ y = x.rest ↔ x = a + y; (elim) Used terms: x, a, y