| n ≠ 0, n ≤ # x0, ∀ n, y, a. n < # x0 → (x0 + y)[n, a] = x0[n, a] + y ⊦ a0 ' + (x0 + y)[n -1, a] = (a0 ' + x0)[n, a] + y |
n ≤ # x0, ∀ n, y, a. n < # x0 → (x0 + y)[n, a] = x0[n, a] + y ⊦ n = 0, a0 ' + (x0 + y)[n - 1, a] = (a0 ' + x0)[n, a] + y
Used simplifier rules: pred-03: ⊦ n -1 = n - 1; from specification nat