intro D I V E _
Δ : List Formula
F : Formula
⊢ ∀ (D : Type) (I : Interpretation D) (V : VarAssignment D) (E : Env),
    (∀ H ∈ [], Holds D I V E H) → Holds D I V E (false_.iff_ true_.not_)
Δ : List Formula
F : Formula
D : Type
I : Interpretation D
V : VarAssignment D
E : Env
a✝ : ∀ H ∈ [], Holds D I V E H
⊢ Holds D I V E (false_.iff_ true_.not_)