rw [forAllRel_cons_left, h_ind]
α : Type u_1
β : Type u_2
r : α → β → Prop
b : β
bs : List β
a : α
as : List α
h_ind : List.forAllRel r as (b :: bs) = (forAll (fun x => r x b) as ∧ List.forAllRel r as bs)
⊢ List.forAllRel r (a :: as) (b :: bs) = (forAll (fun x => r x b) (a :: as) ∧ List.forAllRel r (a :: as) bs)
α : Type u_1
β : Type u_2
r : α → β → Prop
b : β
bs : List β
a : α
as : List α
h_ind : List.forAllRel r as (b :: bs) = (forAll (fun x => r x b) as ∧ List.forAllRel r as bs)
⊢ (forAll (r a) (b :: bs) ∧ forAll (fun x => r x b) as ∧ List.forAllRel r as bs) =
    (forAll (fun x => r x b) (a :: as) ∧ List.forAllRel r (a :: as) bs)