English
div2(n+1) = if bodd(n) then succ(div2(n)) else div2(n).
Русский
div2(n+1) = если bodd(n), то succ(div2(n)), иначе div2(n).
LaTeX
$$$\mathrm{div2}(n+1) = \mathrm{cond}(\mathrm{bodd}(n), \mathrm{succ}(\mathrm{div2}(n)), \mathrm{div2}(n))$$$
Lean4
@[simp]
theorem div2_succ (n : ℕ) : div2 (n + 1) = cond (bodd n) (succ (div2 n)) (div2 n) :=
by
simp only [bodd, boddDiv2, div2]
rcases boddDiv2 n with ⟨_ | _, _⟩ <;> simp