tauto
v t : VarName
phi : Formula
phi_ih : ∀ (binders : Finset VarName), v ∈ binders → replaceFreeAux v t binders phi = phi
binders : Finset VarName
h1 : v ∈ binders
⊢ (replaceFreeAux v t binders phi).not_ = phi.not_
no goals