English
The implicit function of complemented derivatives correctly inverts f on the image: applying the complemented implicit function to the pair (f a, 0) yields a.
Русский
Неявная функция в дополненном виде восстанавливает исходное: применение неявной функции к паре (f(a), 0) даёт a.
LaTeX
$$$ hf.implicitFunctionOfComplemented(f,f',hf',hker)(f(a),0) = a $$$
Lean4
@[simp]
theorem implicitFunctionOfComplemented_apply_image (hf : HasStrictFDerivAt f f' a) (hf' : range f' = ⊤)
(hker : (ker f').ClosedComplemented) : hf.implicitFunctionOfComplemented f f' hf' hker (f a) 0 = a := by
simpa only [implicitToOpenPartialHomeomorphOfComplemented_self] using
(hf.implicitToOpenPartialHomeomorphOfComplemented f f' hf' hker).left_inv
(hf.mem_implicitToOpenPartialHomeomorphOfComplemented_source hf' hker)