Problem 1501 (difficulty: 3/10)
Assume that \(\displaystyle f:\R\to\R\) is Lipschitz, and \(\displaystyle \forall x,y~ |f(x)-f(y)|\le K|x-y|\).
(a) Show that \(\displaystyle f\) is the integral-function of a Lebesgue-measurable \(\displaystyle g\).
(b) Show that \(\displaystyle |g|\le K\) a.e.