induction p with
| nil => rfl
| cons _ p' ih => simp [ih p']
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✝ p : Walk G u v
⊢ Walk.map Hom.id p = p
no goals