English
If f is analytic on s, then for every n, the nth iterated derivative is analytic on s.
Русский
Если f аналитична на s, то для каждого n аналитична n-я итерационная производная на s.
LaTeX
$$$\text{AnalyticOnNhd } 𝕜 f s \to IsOpen s \to ∀ n, AnalyticOnNhd 𝕜 (Nat.iterate deriv n f) s$$$
Lean4
theorem iterated_deriv [CompleteSpace F] (h : AnalyticAt 𝕜 f x) (n : ℕ) : AnalyticAt 𝕜 (deriv^[n] f) x := by
induction n with
| zero => exact h
| succ n IH => simpa only [Function.iterate_succ', Function.comp_apply] using IH.deriv