simp only [Formula.lc_at] at h2
D : Type
I : Interpretation D
z X : String
vs : List Var
V : VarAssignment D
j : ℕ
h1 : free_ z ∉ vs
h2 : Formula.lc_at j (pred_ X vs)
⊢ Holds D I V (pred_ X vs) ↔ Holds D I (V ∘ Var.close j (free_ z)) (Formula.openList j [free_ z] (pred_ X vs))
D : Type
I : Interpretation D
z X : String
vs : List Var
V : VarAssignment D
j : ℕ
h1 : free_ z ∉ vs
h2 : ∀ v ∈ vs, Var.lc_at j v
⊢ Holds D I V (pred_ X vs) ↔ Holds D I (V ∘ Var.close j (free_ z)) (Formula.openList j [free_ z] (pred_ X vs))