| a0 ∈ x, ∀ a, x. a ∈ x1 ∧ a ∈ x → (∃ b, y, y0. b ∈ x ∧ x1 = y + b ' + y0 ∧ disj(x, y)) ⊦ ∃ b, y, y0. b ∈ x ∧ a0 ' + x1 = y + b ' + y0 ∧ disj(x, y) |
Used simplifier rules: e: ⊦ disj(x, []);% ⊦ [] + x = x; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ a ' + x = a ' + y ↔ x = y; (s) Used terms: a0, [], x1