apply IsDeduct.mp_ (Q.not_.imp_ (forall_ v Q.not_))
case h1
P Q : Formula
v : VarName
h1 : ¬isFreeIn v Q
⊢ IsDeduct {forall_ v (P.imp_ Q)} ((forall_ v P.not_).not_.imp_ Q)
case h1.a
P Q : Formula
v : VarName
h1 : ¬isFreeIn v Q
⊢ IsDeduct {forall_ v (P.imp_ Q)} ((Q.not_.imp_ (forall_ v Q.not_)).imp_ ((forall_ v P.not_).not_.imp_ Q))

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