
Journal of Convex Analysis 25 (2018), No. 1, 103118 Copyright Heldermann Verlag 2018 The Typical Irregularity of Virtual Convex Bodies Rolf Schneider Mathematisches Institut, AlbertLudwigsUniversität, 79104 Freiburg, Germany rolf.schneider@math.unifreiburg.de The semigroup of convex bodies in R^{n} with Minkowski addition has a canonical embedding into an abelian group; its elements have been called virtual convex bodies. Geometric interpretations of such virtual convex bodies have been particularly fruitful under the restriction to polytopes. For general convex bodies, mainly the planar case has been studied, as a part of the more general investigation of hedgehogs. Here we restrict ourselves to strictly convex bodies in R^{n}. A particularly natural geometric interpretation of virtual convex bodies can then be seen in the set of differences of boundary points of two convex bodies with the same outer normal vector. We describe how in the typical case (in the sense of Baire category) this leads to a highly singular object. Keywords: Virtual convex body, difference of support functions, Baire category, hedgehog. MSC: 52A30; 53A07 [ Fulltextpdf (282 KB)] for subscribers only. 