cases h1
phi psi : Formula
phi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs phi → phi.metaVarSet = ∅
psi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs psi → psi.metaVarSet = ∅
vs : List VarName
h1 : NoMetaVarAndAllFreeInList vs phi ∧ NoMetaVarAndAllFreeInList vs psi
⊢ phi.metaVarSet ∪ psi.metaVarSet = ∅
case intro
phi psi : Formula
phi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs phi → phi.metaVarSet = ∅
psi_ih : ∀ (vs : List VarName), NoMetaVarAndAllFreeInList vs psi → psi.metaVarSet = ∅
vs : List VarName
left✝ : NoMetaVarAndAllFreeInList vs phi
right✝ : NoMetaVarAndAllFreeInList vs psi
⊢ phi.metaVarSet ∪ psi.metaVarSet = ∅