English
A variant reformulation of differentiability on a set via maximal atlas with an appended prime'
Русский
Вариант формулировки через максимальный атлас с дополнительной примой'
LaTeX
$$MDifferentiableWithinAt I I' f s x ↔ ContinuousWithinAt f s x ∧ DifferentiableOn 𝕜 (e'.extend I' ∘ f ∘ (e.extend I).symm) (e.extend I '' s)$$
Lean4
theorem mdifferentiableWithinAt_iff_of_mem_maximalAtlas {x : M} (he : e ∈ maximalAtlas I 1 M)
(he' : e' ∈ maximalAtlas I' 1 M') (hx : x ∈ e.source) (hy : f x ∈ e'.source) :
MDifferentiableWithinAt I I' f s x ↔
ContinuousWithinAt f s x ∧
DifferentiableWithinAt 𝕜 (e'.extend I' ∘ f ∘ (e.extend I).symm) ((e.extend I).symm ⁻¹' s ∩ range I)
(e.extend I x) :=
differentiableWithinAt_localInvariantProp.liftPropWithinAt_indep_chart he hx he' hy