∀ {α : Type u_1} (c₁ : Computation α) (a : α) (motive : (∃ a_1 ∈ c₁, (fun x1 x2 => x1 = x2) a_1 a) → Prop)
  (x : ∃ a_1 ∈ c₁, (fun x1 x2 => x1 = x2) a_1 a), (∀ (b : α) (b1 : b ∈ c₁) (ab : b = a), motive ⋯) → motive x