English
For every n ∈ ℕ, the value bodd(n) equals the first bit in the binary representation n.bits (the head of the list): bodd(n) = headI(n.bits).
Русский
Для любого n ∈ ℕ значение bodd(n) равно первому биту двоичной записи n.bits (голове списка): bodd(n) = headI(n.bits).
LaTeX
$$$$ n\\bodd = n.bits.headI $$$$
Lean4
theorem bodd_eq_bits_head (n : ℕ) : n.bodd = n.bits.headI := by
induction n using Nat.binaryRec' with
| zero => simp
| bit _ _ h => simp [bodd_bit, bits_append_bit _ _ h]