case neg c1 =>
  simp at h1
  push_neg at h1
  cases h1
  case intro h1_left h1_right =>
    apply xs_ih ys_tl h1_right
α β : Type
inst✝ : DecidableEq α
f : α → β
v xs_hd : α
xs_tl : List α
xs_ih : ∀ (ys : List β), v ∉ xs_tl → updateListITE f xs_tl ys v = f v
h1 : v ∉ xs_hd :: xs_tl
ys_hd : β
ys_tl : List β
c1 : ¬v = xs_hd
⊢ updateListITE f xs_tl ys_tl v = f v
no goals