| # x = n0 + n, x = firstn(n0, x) + restn(n0, x) ⊦ n = 0, ∃ y. x = y + lastn(n, x) ∧ # y = n0 |
# x = n0 + n, x = firstn(n0, x) + restn(n0, x) ⊦ n = 0, x = firstn(n0, x) + lastn(n, x) ∧ # firstn(n0, x) = n0, ∃ y. x = y + lastn(n, x) ∧ # y = n0
Used terms: firstn(n0, x)