| x1 ⊑ y, ordered≤(y), (∃ x0. x1 ⊑ x0 ∧ ordered≤(x0)) → ordered≤(x1) ⊦ x1 = [], y = [], y.first < a, ¬ x1.first < a ∧ ordered≤(x1) |
y = a0 + y0, x1 ⊑ y, ordered≤(y), (∃ x0. x1 ⊑ x0 ∧ ordered≤(x0)) → ordered≤(x1) ⊦ x1 = [], y = [], a0 < a, ¬ x1.first < a ∧ ordered≤(x1)
Used simplifier rules: x ≠ [] ⊦ a = x.first ∧ y = x.rest ↔ x = a + y; (elim) Used terms: y, a0, y0