{α : Sort u_1} →
  {β : Sort u_2} →
    {s₁ : Setoid α} →
      {s₂ : Setoid β} →
        (q₁ : Quotient s₁) →
          (q₂ : Quotient s₂) →
            (f : α → β → Prop) →
              (h : ∀ (a₁ : α) (b₁ : β) (a₂ : α) (b₂ : β), s₁ a₁ a₂ → s₂ b₁ b₂ → f a₁ b₁ = f a₂ b₂) →
                [(a : α) → DecidablePred (f a)] → Decidable (q₁.liftOn₂' q₂ f h)