English
If h is MDifferentiableWithinAt, then mfderivWithin equals the MF-derivative value mfderivWithin I I' f s x.
Русский
Если h — MDifferentiableWithinAt, то mfderivWithin равен MF-производной mfderivWithin I I' f s x.
LaTeX
$$$ (h : MDifferentiableWithinAt I I' f s x) \Rightarrow (mfderivWithin I I' f s x = mfderiv I I' f x) $$$
Lean4
protected theorem mfderivWithin (h : MDifferentiableWithinAt I I' f s x) :
mfderivWithin I I' f s x =
fderivWithin 𝕜 (writtenInExtChartAt I I' x f :) ((extChartAt I x).symm ⁻¹' s ∩ range I) ((extChartAt I x) x) :=
by simp only [mfderivWithin, h, if_pos]