English
If q and p provide Taylor series up to n for all n in their domains, then the Taylor series of the composition g ∘ f is given by q.taylorComp p.
Русский
Если q и p задают разложения Тейлора, то композиция g ∘ f имеет разложение, данное q.taylorComp p.
LaTeX
$$HasFTaylorSeriesUpToOn n g q t → HasFTaylorSeriesUpToOn n f p s → MapsTo f s t → HasFTaylorSeriesUpToOn n (g ∘ f) (fun x => (q (f x)).taylorComp (p x)) s$$
Lean4
@[simp]
theorem compAlongOrderedFinpartition_apply {n : ℕ} (q : FormalMultilinearSeries 𝕜 F G)
(p : FormalMultilinearSeries 𝕜 E F) (c : OrderedFinpartition n) (v : Fin n → E) :
(q.compAlongOrderedFinpartition p c) v = q c.length (c.applyOrderedFinpartition (fun m ↦ (p (c.partSize m))) v) :=
rfl