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