| ∀ a. a ∈ x0 → (∃ y, z. x0 = y + a ' + z ∧ ¬ a ∈ y) ⊦ a0 ∈ x0, ∃ y, z. a0 ' + x0 = y + a0 ' + z ∧ ¬ a0 ∈ y |
Used simplifier rules: Nil: ⊦ [] + x = x;%a: ⊦ (x + y) + z = x + y + z;%app-08: ⊦ a ' + x = a ' + y ↔ x = y;%in-empty: ⊦ ¬ a ∈ []; Used terms: [], x0