exact ⟨p.cseqDef.rew (Rew.embSubsts <| #0 :> fun i ↦ &(v i)), by
  intro w; simpa using c.cseq_defined_iff (w 0 :> v) |>.symm⟩
case hP.h.h₁
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
k : ℕ
p : Formulae k
c : Construction M p
v : Fin k → M
⊢ Definable ℒₒᵣ (𝚺, 0 + 1) fun v_1 => c.CSeq v (v_1 0)
no goals