exact psi_ih h1_right
case h.e'_2
τ : PredName → PredName
phi psi : Formula
phi_ih : phi.predVarSet = ∅ → sub τ phi = phi
psi_ih : psi.predVarSet = ∅ → sub τ psi = psi
h1_left : phi.predVarSet = ∅
h1_right : psi.predVarSet = ∅
⊢ sub τ psi = psi
no goals