On Lipschitz and d.c. surfaces of finite codimension in a Banach space
Abstract
Properties of Lipschitz and d.c. surfaces of finite codimension in a Banach space, and properties of generated
σ
-ideals are studied. These
σ
-ideals naturally appear in the differentiation theory and in the abstract approximation theory. Using these properties, we improve an unpublished result of M. Heisler which gives an alternative proof of a result of D. Preiss on singular points of convex functions.