{p : ℕ} →
  {f : ⦃R : Type u_2⦄ → [CommRing R] → WittVector p R → WittVector p R → WittVector p R} →
    {motive : WittVector.IsPoly₂ p f → Sort u} →
      ((poly :
            ∃ φ,
              ∀ ⦃R : Type u_2⦄ [inst : CommRing R] (x y : WittVector p R),
                (f x y).coeff = fun n => WittVector.peval (φ n) ![x.coeff, y.coeff]) →
          motive ⋯) →
        (t : WittVector.IsPoly₂ p f) → motive t