English
Powers of an analytic function are analytic within a set.
Русский
Степени аналитической функции аналитичны внутри множества.
LaTeX
$$$\text{AnalyticWithinAt}_{\mathbb{k}}(f,s,z) \Rightarrow \forall n, \text{AnalyticWithinAt}_{\mathbb{k}}(f^n,s,z)$$$
Lean4
/-- Powers of analytic functions (into a normed `𝕜`-algebra) are analytic. -/
theorem fun_pow {f : E → A} {z : E} {s : Set E} (hf : AnalyticWithinAt 𝕜 f s z) (n : ℕ) :
AnalyticWithinAt 𝕜 (fun x ↦ f x ^ n) s z := by
induction n with
| zero =>
simp only [pow_zero]
apply analyticWithinAt_const
| succ m hm =>
simp only [pow_succ]
exact hm.mul hf