Miscellaneous Questions Regarding Hedgehogs
摘要
We consider some miscellaneous questions regarding hedgehogs and their applications, beginning with convolution of hedgehogs. We study the generic singularities that occur during an eversion of the sphere following a generic path of hedgehogs and show that such a path necessarily includes hedgehogs carrying positive swallowtails. Finally, we show through an example that hedgehogs are not only a generalization of convex bodies, but also a way of thinking about convex hypersurfaces in conjunction with their spherical images. Our example consists in giving a set of conditions that is necessary and sufficient for the existence and uniqueness up to translations of a 3-dimensional polytope in \(\mathbb {R}^{3}\) having N facets with given unit outward normal vectors and corresponding facet parameters.