apply IsDeduct.mp_ ((forall_ v (P.imp_ Q)).imp_ (P.imp_ (forall_ v Q)))
P Q : Formula
v : VarName
h1 : ¬isFreeIn v P
⊢ IsProof ((forall_ v (P.imp_ Q)).iff_ (P.imp_ (forall_ v Q)))
case a
P Q : Formula
v : VarName
h1 : ¬isFreeIn v P
⊢ IsDeduct ∅
    (((forall_ v (P.imp_ Q)).imp_ (P.imp_ (forall_ v Q))).imp_ ((forall_ v (P.imp_ Q)).iff_ (P.imp_ (forall_ v Q))))

case a
P Q : Formula
v : VarName
h1 : ¬isFreeIn v P
⊢ IsDeduct ∅ ((forall_ v (P.imp_ Q)).imp_ (P.imp_ (forall_ v Q)))