| ∀ y, z. (x0 + y) + z = x0 + y + z ⊦ ((a + x0) + y) + z = (a + x0) + y + z |
∀ y, z. (x0 + y) + z = x0 + y + z ⊦ (x0 + y) + z = x0 + y + z
Used simplifier rules: Cons: ⊦ (a + x) + y = a + (x + y);%f: ⊦ a + x = a + y ↔ x = y; from specification list-data