induction as
α : Type u
r : α → α → Prop
inst✝ : Trans r r r
β : Type v
r' : β → β → Prop
f : α → Option β
rel_pres : ∀ (a₁ a₂ : α), r a₁ a₂ → ∀ (b₁ b₂ : β), f a₁ = some b₁ → f a₂ = some b₂ → r' b₁ b₂
as : List α
⊢ Ascending r as → Ascending r' (filterMap f as)
case nil
α : Type u
r : α → α → Prop
inst✝ : Trans r r r
β : Type v
r' : β → β → Prop
f : α → Option β
rel_pres : ∀ (a₁ a₂ : α), r a₁ a₂ → ∀ (b₁ b₂ : β), f a₁ = some b₁ → f a₂ = some b₂ → r' b₁ b₂
⊢ Ascending r [] → Ascending r' (filterMap f [])

case cons
α : Type u
r : α → α → Prop
inst✝ : Trans r r r
β : Type v
r' : β → β → Prop
f : α → Option β
rel_pres : ∀ (a₁ a₂ : α), r a₁ a₂ → ∀ (b₁ b₂ : β), f a₁ = some b₁ → f a₂ = some b₂ → r' b₁ b₂
head✝ : α
tail✝ : List α
tail_ih✝ : Ascending r tail✝ → Ascending r' (filterMap f tail✝)
⊢ Ascending r (head✝ :: tail✝) → Ascending r' (filterMap f (head✝ :: tail✝))