English
The projection map from the total space to the base space is C^n with respect to the chosen model of differentiability. In particular, the map π F E: TotalSpace F E → B is C^n.
Русский
Отображение проекции π F E: TotalSpace F E → B является C^n в рамках выбранной модели гладкости.
LaTeX
$$$\displaystyle \operatorname{ContMDiff} (IB. prod 𝓘(\mathit{𝕜}, F)) IB n \; \pi F E.$$$$
Lean4
theorem contMDiff_proj : ContMDiff (IB.prod 𝓘(𝕜, F)) IB n (π F E) := fun x ↦
by
have : ContMDiffAt (IB.prod 𝓘(𝕜, F)) (IB.prod 𝓘(𝕜, F)) n id x := contMDiffAt_id
rw [contMDiffAt_totalSpace] at this
exact this.1