(max(x) < a ⊃ a;max(x)) < max(x) ⊦ x = []
Used simplifier rules: max-rec: ⊦ x ≠ [] → max(a ' + x) = (max(x) < a ⊃ a;max(x));%a: ⊦ (x + y) + z = x + y + z; from specification list