Counterexamples Related to Rotations of Shadows of Convex Bodies

Abstract

We construct examples of two convex bodies $K,L$ in ${\mathbb{R}}^n$, such that every projection of $K$ onto a $(n-1)$-dimensional subspace can be rotated to be contained in the corresponding projection of $L$, but $K$ itself cannot be rotated to be contained in $L$. We also find necessary conditions on $K$ and $L$ to ensure that $K$ can be rotated to be contained in $L$ if all the $(n-1)$-dimensional projections have this property.

17 pages, 11 figures