| ∀ y. x0 + y ⊑ x0 → y = [], (a + x0) + y ⊑ a + x0 ⊦ y = [] |
x0 + y ⊑ x0, ∀ y. x0 + y ⊑ x0 → y = [] ⊦ y = []
Used simplifier rules: prefix-rec-03: ⊦ a ' + x ⊑ b ' + y ↔ a = b ∧ x ⊑ y;%a: ⊦ (x + y) + z = x + y + z; from specification list%c: ⊦ a + x = a ' + x; from specification list