Hyperspaces of convex bodies of constant width

Abstract

Let n be a natural number equal or greater than 2. In this paper we study the topological structure of certain hyperspaces of convex subsets of constant width, equipped with the Hausdorff metric topology. We focus our attention on the hyperspace cw_D(R^n) of all compact convex subsets with constant width d\in D, where D is a convex subset of [0,\infty). Our main result states that cw_D(R^n) is homeomorphic to D\times R^n\times Q, where Q denotes the Hilbert cube. We also prove that the hyperspace crw_D(R^n), consisting of all pairs of compact convex sets of constant relative width d\in D is homeomorphic to cw_D(R^n). In particular, we prove that the hyperspace cw(R^n) of all compact convex bodies of constant width, as well as the hyperspace crw(R^n) of all pairs of compact convex sets of constant relative positive width are homeomorphic to R^{n+1}\times Q.