cases h
α : Type u_1
p✝ : α → Prop
inst✝¹ : DecidablePred p✝
p : α → Prop
inst✝ : DecidablePred p
x : α
xs : List α
ih : ∀ (i : xs.Index) (hi : p i.val) (j : (List.sublist p xs).Index), sublist p i hi = j ↔ i = unsublist p j
j✝ : (List.sublist p (x :: xs)).Index
hx : p x
i : xs.Index
hi : p i.tail.val
x✝ : (⟨x, ⋯⟩ :: List.sublist p xs).Index
j : (List.sublist p xs).Index
ht : ⋯ ▸ j✝ = j.tail
h : i.tail = (unsublist p j).tail
⊢ ⋯ ▸ (sublist p i hi).tail = j✝
case refl
α : Type u_1
p✝ : α → Prop
inst✝¹ : DecidablePred p✝
p : α → Prop
inst✝ : DecidablePred p
x : α
xs : List α
ih : ∀ (i : xs.Index) (hi : p i.val) (j : (List.sublist p xs).Index), sublist p i hi = j ↔ i = unsublist p j
j✝ : (List.sublist p (x :: xs)).Index
hx : p x
x✝ : (⟨x, ⋯⟩ :: List.sublist p xs).Index
j : (List.sublist p xs).Index
ht : ⋯ ▸ j✝ = j.tail
hi : p (unsublist p j).tail.val
⊢ ⋯ ▸ (sublist p (unsublist p j) hi).tail = j✝