Definable Lipschitz selections for affine-set valued maps

Adam Parusiński, Armin Rainer

Whitney's extension problem, i.e., how one can tell whether a function $f:X\to \mathbb{R}$, $X\subseteq {\mathbb{R}}^n$, is the restriction of a $C^m$-function on ${\mathbb{R}}^n$, wa…