unfold Formula.metaVarSet
phi : Formula
phi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs phi → phi.metaVarSet = ∅
vs : List VarName
h1 : NoMetaVarAndAllFreeInList vs phi
⊢ phi.not_.metaVarSet = ∅
phi : Formula
phi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs phi → phi.metaVarSet = ∅
vs : List VarName
h1 : NoMetaVarAndAllFreeInList vs phi
⊢ phi.metaVarSet = ∅