| max(x0) = x0.last, x0.last < a, ordered≤(a ' + x0) ⊦ a = x0.last, x0 = [] |
⊦ ordered≤(y) ↔ # y ≤ 1 ∨ ¬ y.tail.head < y.head ∧ ordered≤(y.tail)
max(x0) = x0.last, x0.last < a, #(a ' + x0) ≤ 1 ∨ ¬ (a ' + x0).tail.head < (a ' + x0).head ∧ ordered≤((a ' + x0).tail) ⊦ a = x0.last, x0 = []
Used terms: a ' + x0