rw [←val_unmap (s.r x)]
α : Type u_1
s : Setoid α
inst✝ : DecidableRel Setoid.r
xs✝ : List α
x : α
xs : List α
ih : ∀ {i : xs.Index} {j : (List.dedup s xs).Index}, Setoid.r i.val j.val → dedup s i = j
i : (x :: xs).Index
j : (List.dedup s (x :: xs)).Index
h : Setoid.r x j.val
ha : Logic.Any (List.map (Setoid.r x) xs)
⊢ Setoid.r x (unmap (Setoid.r x) ha.get).val
α : Type u_1
s : Setoid α
inst✝ : DecidableRel Setoid.r
xs✝ : List α
x : α
xs : List α
ih : ∀ {i : xs.Index} {j : (List.dedup s xs).Index}, Setoid.r i.val j.val → dedup s i = j
i : (x :: xs).Index
j : (List.dedup s (x :: xs)).Index
h : Setoid.r x j.val
ha : Logic.Any (List.map (Setoid.r x) xs)
⊢ ha.get.val