| a ' + x + b ' + y = x0 + b ' + y0, a ∈ x0 ⊦ b ∈ x0, b ∈ x, a ' + x = x0 ∧ y = y0 |
Used simplifier rules: Nil: ⊦ [] + x = x;%a: ⊦ (x + y) + z = x + y + z;%c-06: ⊦ a ' + x = b ' + y ↔ a = b ∧ x = y;%c: ⊦ a + x = a ' + x;%a: ⊦ (x + y) + z = x + y + z;%c-06: ⊦ a ' + x = b ' + y ↔ a = b ∧ x = y;%in-rec: ⊦ a ∈ b ' + x ↔ a = b ∨ a ∈ x;%inapp-03: ⊦ ¬ a ∈ y ∧ ¬ b ∈ x → (x + a ' + z = y + b ' + y0 ↔ a = b ∧ x = y ∧ z = y0);%list freely generated by [], +;;