simp only [shift]
D : Type
I : Interpretation D
x : String
phi : Formula
phi_ih :
  ∀ (V V' : VarAssignment D), (∀ (v : Var), occursFreeIn v phi → V v = V' v) → (Holds D I V phi ↔ Holds D I V' phi)
V V' : VarAssignment D
h1 : ∀ (v : Var), occursFreeIn (lift v) phi → V v = V' v
d : D
a1 : occursFreeIn (bound_ 0) phi
⊢ shift D V d (bound_ 0) = shift D V' d (bound_ 0)
no goals