tauto
v t : VarName
h1 : ¬v = t
phi psi : Formula
phi_ih : ¬isFreeIn v (fastReplaceFree v t phi)
psi_ih : ¬isFreeIn v (fastReplaceFree v t psi)
⊢ ¬(isFreeIn v (fastReplaceFree v t phi) ∨ isFreeIn v (fastReplaceFree v t psi))
no goals