intro i
case h.right.right
α : Type u_1
r : α → α → Prop
n : ℕ
IH :
  ∀ (x z : α) (ys : Vector α n.succ),
    (x = ys.head ∧ z = ys.last ∧ ∀ (i : Fin n), r (ys.get i.castSucc) (ys.get i.succ)) → Relation.ReflTransGen r x z
x z : α
ys : Vector α (n + 1).succ
x_is_head : x = ys.head
z_is_last : z = ys.last
steprel : ∀ (i : Fin (n + 1)), r (ys.get i.castSucc) (ys.get i.succ)
y : α := ys.tail.head
⊢ ∀ (i : Fin n), r (ys.get i.castSucc.succ) (ys.get i.succ.succ)
case h.right.right
α : Type u_1
r : α → α → Prop
n : ℕ
IH :
  ∀ (x z : α) (ys : Vector α n.succ),
    (x = ys.head ∧ z = ys.last ∧ ∀ (i : Fin n), r (ys.get i.castSucc) (ys.get i.succ)) → Relation.ReflTransGen r x z
x z : α
ys : Vector α (n + 1).succ
x_is_head : x = ys.head
z_is_last : z = ys.last
steprel : ∀ (i : Fin (n + 1)), r (ys.get i.castSucc) (ys.get i.succ)
y : α := ys.tail.head
i : Fin n
⊢ r (ys.get i.castSucc.succ) (ys.get i.succ.succ)