∀ {α : Sort u_2} {β : α → Sort u_3} {C₂ : (a : α) → β a → Sort u_1} [inst : ∀ (a : α) (b : β a), Nonempty (C₂ a b)]
  {R : (a : α) ×' β a → (a : α) ×' β a → Prop}
  {F : (a : α) → (b : β a) → ((a' : α) → (b' : β a') → R ⟨a', b'⟩ ⟨a, b⟩ → C₂ a' b') → C₂ a b} (wf : WellFounded R)
  {a : α} {b : β a},
  WellFounded.extrinsicFix₂ R F a b = wf.fix (fun x G => F x.fst x.snd fun a b h => G ⟨a, b⟩ h) ⟨a, b⟩