apply phi_ih
case a.h.a
D : Type
I : Interpretation D
zs : List String
phi psi : Formula
phi_ih :
  ∀ (V : VarAssignment D) (j : ℕ),
    Holds D I (V ∘ Var.openList j (List.map free_ zs)) phi ↔ Holds D I V (Formula.openList j (List.map free_ zs) phi)
psi_ih :
  ∀ (V : VarAssignment D) (j : ℕ),
    Holds D I (V ∘ Var.openList j (List.map free_ zs)) psi ↔ Holds D I V (Formula.openList j (List.map free_ zs) psi)
V : VarAssignment D
j : ℕ
⊢ Holds D I (V ∘ Var.openList j (List.map free_ zs)) phi ↔ Holds D I V (Formula.openList j (List.map free_ zs) phi)
no goals