| ∀ x. lastn(n0, lastn(n0, x)) = lastn(n0, x) ⊦ lastn(n0 + 1, lastn(n0 + 1, x)) = lastn(n0 + 1, x) |
⊦ lastn(n + 1, x) = lastn(n, x.butlast) + x.last
∀ x. lastn(n0, lastn(n0, x)) = lastn(n0, x) ⊦ lastn(n0 + 1, lastn(n0, x.butlast) + x.last) = lastn(n0, x.butlast) + x.last
Used terms: x, n0