| ordered≤(a ' + x1), ordered≤(x1 + a0 ' + y), ∀ x. ordered≤(x) ∧ (x ≠ [] → ¬ x.first < x1.last) → ordered≤(x1 + x) ⊦ x1 = [], ordered≤(a ' + x1 + a0 ' + y), a0 < x1.last |
⊦ ordered≤(y) ↔ # y ≤ 1 ∨ ¬ y.rest.first < y.first ∧ ordered≤(y.rest)
ordered≤(a ' + x1), ordered≤(x1 + a0 ' + y), ∀ x. ordered≤(x) ∧ (x ≠ [] → ¬ x.first < x1.last) → ordered≤(x1 + x) ⊦ x1 = [], #(a ' + x1 + a0 ' + y) ≤ 1 ∨ ¬ (a ' + x1 + a0 ' + y).rest.first < (a ' + x1 + a0 ' + y).first ∧ ordered≤((a ' + x1 + a0 ' + y).rest), a0 < x1.last
Used terms: a ' + x1 + a0 ' + y