∀ {k : Type u_1} [inst : Ring k] (I : Set k) {n : ℕ} {fs : Finset (Fin (n + 1))} {w : Fin (n + 1) → k}
  (motive : ((∀ i ∈ fs, w i ∈ I) ∧ ∀ i ∉ fs, w i = 0) → Prop) (x : (∀ i ∈ fs, w i ∈ I) ∧ ∀ i ∉ fs, w i = 0),
  (∀ (hii : ∀ i ∈ fs, w i ∈ I) (hi0 : ∀ i ∉ fs, w i = 0), motive ⋯) → motive x