exact h2_left
case right.right.h1
α : Type
inst✝ : DecidableEq α
xs_hd : α
xs_tl : List α
ys_hd : α
ys_tl : List α
h1 : xs_tl.length = ys_tl.length
h2_left : xs_hd ∉ xs_tl
h2_right : xs_tl.Nodup
h3_left : ys_hd ∉ ys_tl
h3_right : ys_tl.Nodup
f : α → α
a1_left : InjOn f xs_tl
a1_right : map f xs_tl = ys_tl
⊢ xs_hd ∉ xs_tl
no goals