Rotation inside convex Kakeya sets
Abstract
Let be a convex body (a compact convex set) in , that contains a copy of another body in every possible orientation. Is it always possible to continuously move any one copy of into another, inside ? As a stronger question, is it always possible to continuously select, for each orientation, one copy of in that orientation? These questions were asked by Croft. We show that, in two dimensions, the stronger question always has an affirmative answer. We also show that in three dimensions the answer is negative, even for the case when is a line segment -- but that in any dimension the first question has a positive answer when is a line segment. And we prove that, surprisingly, the answer to the first question is negative in dimension four for general .
Cite
@article{arxiv.2209.09728,
title = {Rotation inside convex Kakeya sets},
author = {Barnabás Janzer},
journal= {arXiv preprint arXiv:2209.09728},
year = {2022}
}
Comments
25 pages, 5 figures, updated introduction