intro D I V E _
Δ : List Formula
F : Formula
v : VarName
phi : Formula
ih : ¬isFreeIn v phi
⊢ ∀ (D : Type) (I : Interpretation D) (V : VarAssignment D) (E : Env),
    (∀ H ∈ [], Holds D I V E H) → Holds D I V E (phi.imp_ (forall_ v phi))
Δ : List Formula
F : Formula
v : VarName
phi : Formula
ih : ¬isFreeIn v phi
D : Type
I : Interpretation D
V : VarAssignment D
E : Env
a✝ : ∀ H ∈ [], Holds D I V E H
⊢ Holds D I V E (phi.imp_ (forall_ v phi))