apply T_18_6 P_u P_v u v h3
case h2
P_u P_v Q Q' : Formula
u v : VarName
Δ : Set Formula
h1 : IsDeduct Δ Q
h2 : IsReplOfFormulaInFormula (forall_ u P_u) (forall_ v P_v) Q Q'
h3 : Similar P_u P_v u v
⊢ IsProof ((forall_ u P_u).iff_ (forall_ v P_v))
no goals