English

Typical curvature behaviour of bodies of constant width

Metric Geometry 2014-04-29 v1

Abstract

It is known that an nn-dimensional convex body which is typical in the sense of Baire category, shows a simple, but highly non-intuitive curvature behaviour: at almost all of its boundary points, in the sense of measure, all curvatures are zero, but there is also a dense and uncountable set of boundary points at which all curvatures are infinite. The purpose of this paper is to find a counterpart to this phenomenon for typical convex bodies of given constant width. Such bodies cannot have zero curvatures. A main result says that for a typical nn-dimensional convex body of constant width 11 (without loss of generality), at almost all boundary points, in the sense of measure, all curvatures are equal to 11. (In contrast, note that a ball of width 11 has radius 1/21/2, hence all its curvatures are equal to 22.) Since the property of constant width is linear with respect to Minkowski addition, the proof requires recourse to a linear curvature notion, which is provided by the tangential radii of curvature.

Keywords

Cite

@article{arxiv.1404.7019,
  title  = {Typical curvature behaviour of bodies of constant width},
  author = {Imre Barany and rolf Schneider},
  journal= {arXiv preprint arXiv:1404.7019},
  year   = {2014}
}