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

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