| n ≤ # x0, ∀ n. n ≤ # x0 → butlastn(n, x0) = firstn(# x0 - n, x0) ⊦ a ' + butlastn(n, x0) = a ' + firstn(# x0 - n, x0), 1 + # x0 = n |
n ≤ # x0, ∀ n. n ≤ # x0 → butlastn(n, x0) = firstn(# x0 - n, x0) ⊦ 1 + # x0 = n, butlastn(n, x0) = firstn(# x0 - n, x0)
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ x + y = x + z ↔ y = z; (s)