English
If a function is C^n, then its tangent map is C^m.
Русский
Если функция C^n, то касательное отображение tangentMap тоже C^m.
LaTeX
$$$\forall hf : ContMDiff I I' n f,\; hmn : m + 1 ≤ n \Rightarrow ContMDiff I.tangent I'.tangent m (tangentMap I I' f)$$$
Lean4
/-- If a function is `C^n`, then its bundled derivative is `C^m` when `m+1 ≤ n`. -/
theorem contMDiff_tangentMap (hf : ContMDiff I I' n f) (hmn : m + 1 ≤ n) :
ContMDiff I.tangent I'.tangent m (tangentMap I I' f) :=
by
rw [← contMDiffOn_univ] at hf ⊢
convert hf.contMDiffOn_tangentMapWithin hmn uniqueMDiffOn_univ
rw [tangentMapWithin_univ]