English
MDifferentiableWithinAt I I' f s x holds iff for f1 with f1 = f eventually near x, f1 is MDifferentiableWithinAt f s x.
Русский
MDifferentiableWithinAt I I' f s x эквивалентно тому, что для пары f и f1, где f1 стремится к f ближе к x, выполняется MDifferentiableWithinAt f1 s x.
LaTeX
$$$(\text{MDifferentiableWithinAt } I I' f s x) \iff (MDifferentiableWithinAt I I' f_1 s x)$ при $f_1 =^\{nhdsWithin x s\} f$$$
Lean4
theorem mdifferentiablefWithinAt_iff (h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
MDifferentiableWithinAt I I' f₁ s x ↔ MDifferentiableWithinAt I I' f s x :=
differentiableWithinAt_localInvariantProp.liftPropWithinAt_congr_iff_of_eventuallyEq h₁ hx