Subdifferentiable functions satisfy Lusin properties of class $C^1$ or $C^2$

D. Azagra, J. Ferrera, M. García-Bravo +1

Let $f:{\mathbb{R}}^n\to \mathbb{R}$ be a function. Assume that for a measurable set $\Omega$ and almost every $x\in \Omega$ there exists a vector ${\xi }_x\in {\mathbb{R}}^n$ such that $$\liminf_{h\to…