English
If x and x' are the same point, then the MF derivative at x equals the MF derivative at x'.
Русский
Если точки x и x' совпадают, то MF-дифференциал в x равен MF-дифференциалу в x'.
LaTeX
$$$x'=x \\Rightarrow mfderiv I I' f x = mfderiv I I' f x'$$$
Lean4
theorem tangentMapWithin_congr (h : ∀ x ∈ s, f x = f₁ x) (p : TangentBundle I M) (hp : p.1 ∈ s) :
tangentMapWithin I I' f s p = tangentMapWithin I I' f₁ s p :=
by
refine TotalSpace.ext (h p.1 hp) ?_
rw [tangentMapWithin, h p.1 hp, tangentMapWithin, mfderivWithin_congr h (h _ hp)]