apply IsDeduct.mp_ h1_phi
F : Formula
v : VarName
Δ : Set Formula
h2 : ∀ H ∈ Δ, ¬isFreeIn v H
h1_phi : Formula
h1_1 : h1_phi ∈ Δ
⊢ IsDeduct Δ (forall_ v h1_phi)
case a
F : Formula
v : VarName
Δ : Set Formula
h2 : ∀ H ∈ Δ, ¬isFreeIn v H
h1_phi : Formula
h1_1 : h1_phi ∈ Δ
⊢ IsDeduct Δ (h1_phi.imp_ (forall_ v h1_phi))

case a
F : Formula
v : VarName
Δ : Set Formula
h2 : ∀ H ∈ Δ, ¬isFreeIn v H
h1_phi : Formula
h1_1 : h1_phi ∈ Δ
⊢ IsDeduct Δ h1_phi