intro i a h
α : Type
inst✝¹ : (n : Nat) → OfNat α n
inst✝ : UInt α
x : α
n : Nat
hn : Nat.log2RU (length α) = n
⊢ ∀ (i : Nat) (a : α × α),
    i + 1 < n →
      (match
          match a with
          | (x, snd) =>
            ((x &&& ~~~bitmask (OfNat.ofNat i)) + (x &&& bitmask (OfNat.ofNat i)) >>> (1 <<< OfNat.ofNat i),
              1 <<< OfNat.ofNat (i + 1)) with
        | (x, k) => ((x &&& ~~~bitmask (OfNat.ofNat (i + 1))) + (x &&& bitmask (OfNat.ofNat (i + 1))) >>> k, k <<< 1)) =
        match
          match a with
          | (x, snd) =>
            ((x &&& ~~~bitmask (OfNat.ofNat i)) + (x &&& bitmask (OfNat.ofNat i)) >>> (1 <<< OfNat.ofNat i),
              1 <<< OfNat.ofNat (i + 1)) with
        | (x, snd) =>
          ((x &&& ~~~bitmask (OfNat.ofNat (i + 1))) +
              (x &&& bitmask (OfNat.ofNat (i + 1))) >>> (1 <<< OfNat.ofNat (i + 1)),
            1 <<< OfNat.ofNat (i + 1 + 1))
α : Type
inst✝¹ : (n : Nat) → OfNat α n
inst✝ : UInt α
x : α
n : Nat
hn : Nat.log2RU (length α) = n
i : Nat
a : α × α
h : i + 1 < n
⊢ (match
      match a with
      | (x, snd) =>
        ((x &&& ~~~bitmask (OfNat.ofNat i)) + (x &&& bitmask (OfNat.ofNat i)) >>> (1 <<< OfNat.ofNat i),
          1 <<< OfNat.ofNat (i + 1)) with
    | (x, k) => ((x &&& ~~~bitmask (OfNat.ofNat (i + 1))) + (x &&& bitmask (OfNat.ofNat (i + 1))) >>> k, k <<< 1)) =
    match
      match a with
      | (x, snd) =>
        ((x &&& ~~~bitmask (OfNat.ofNat i)) + (x &&& bitmask (OfNat.ofNat i)) >>> (1 <<< OfNat.ofNat i),
          1 <<< OfNat.ofNat (i + 1)) with
    | (x, snd) =>
      ((x &&& ~~~bitmask (OfNat.ofNat (i + 1))) + (x &&& bitmask (OfNat.ofNat (i + 1))) >>> (1 <<< OfNat.ofNat (i + 1)),
        1 <<< OfNat.ofNat (i + 1 + 1))