induction p with
| nil => simp
| cons _ _ ih =>
  rw [map_cons, cons_isTrail_iff, ih, cons_isTrail_iff]
  apply and_congr_right'
  rw [edges_map, ← List.mem_map_of_injective (Injective.Prod_map hinj hinj)]
  exact Iff.rfl
V : Type u
V' : Type v
V'' : Type w
G : Digraph V
G' : Digraph V'
G'' : Digraph V''
f : G →g G'
f' : G' →g G''
u v u' v' : V
p : Walk G u v
hinj : Injective ↑f
⊢ IsTrail (Walk.map f p) ↔ IsTrail p
no goals