induction h with
| refl => exact absurd hij j.lt_irrefl
| node_left i h =>
  have := h.ascend
  rewrite [Nat.succ_sub_one, Nat.mul_div_right _ (by decide)] at this
  exact this
| node_right i h =>
  have := h.ascend
  conv at this =>
    rw [Nat.succ_sub_one, Nat.add_comm, Nat.add_mul_div_left _ _ (by decide)]
    lhs; change 0 + i; rw [Nat.zero_add]
  exact this
i j : Nat
h : Descendant i j
hij : i < j
⊢ Descendant i ((j - 1) / 2)
no goals