simp
case h1.h1.h2
P Q : Formula
v : VarName
⊢ ∀ H ∈ {forall_ v P, forall_ v ((P.imp_ Q).and_ (Q.imp_ P))}, ¬isFreeIn v H
case h1.h1.h2
P Q : Formula
v : VarName
⊢ ¬isFreeIn v (forall_ v P) ∧ ¬isFreeIn v (forall_ v ((P.imp_ Q).and_ (Q.imp_ P)))