English
If hs is open and h: s.EqOn f g, then AnalyticOnNhd 𝕜 f s ↔ AnalyticOnNhd 𝕜 g s.
Русский
Если s открыто и h: s.Set EqOn f g, то аналитичность на окрестности совпадает для f и g.
LaTeX
$$$\text{IsOpen}(s) \land s.EqOn(f,g) \Rightarrow \text{AnalyticOnNhd}_{\mathcal{K}}(f,s) \iff \text{AnalyticOnNhd}_{\mathcal{K}}(g,s)$$$
Lean4
/-- If a function `f` is analytic on a set `s` and `g` is linear, then `g ∘ f` is analytic
on `s`. -/
theorem comp_analyticOnNhd {s : Set E} (g : F →L[𝕜] G) (h : AnalyticOnNhd 𝕜 f s) : AnalyticOnNhd 𝕜 (g ∘ f) s :=
by
rintro x hx
rcases h x hx with ⟨p, r, hp⟩
exact ⟨g.compFormalMultilinearSeries p, r, g.comp_hasFPowerSeriesOnBall hp⟩