∀ {α : Type u_1} {β : Type u_2} {l : List α} {p : α → α → α → Prop} {f : α → β} {p' : β → β → β → Prop},
  (∀ {a b c : α}, p' (f a) (f b) (f c) → p a b c) → List.Triplewise p' (List.map f l) → List.Triplewise p l