intro heq
case tail.mpr
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
⊢ i.tail = unsublist p j → ⋯ ▸ sublist p i hi = j
case tail.mpr
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
heq : i.tail = unsublist p j
⊢ ⋯ ▸ sublist p i hi = j