English
If HasFTaylorSeriesUpTo n f p holds, then for any m with m ≤ n, p x m equals iteratedFDeriv m f x.
Русский
Если HasFTaylorSeriesUpTo n f p выполняется, то для любого m ≤ n, p x m равно iteratedFDeriv m f x.
LaTeX
$$$\forall n,\ HasFTaylorSeriesUpTo\ n\ f\ p \Rightarrow \forall x,\forall m\le n,\ p\ x\ m = \operatorname{iteratedFDeriv}_{\mathbb{k}}\; m\ f\ x$$$
Lean4
theorem eq_iteratedFDeriv (h : HasFTaylorSeriesUpTo n f p) {m : ℕ} (hmn : m ≤ n) (x : E) :
p x m = iteratedFDeriv 𝕜 m f x := by
rw [← iteratedFDerivWithin_univ]
rw [← hasFTaylorSeriesUpToOn_univ_iff] at h
exact h.eq_iteratedFDerivWithin_of_uniqueDiffOn hmn uniqueDiffOn_univ (mem_univ _)