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Maximal perimeters of polytope sections and origin-symmetry

Banff International Research Station for Mathematical Innovation and Discovery

Let $P\subset\mathbb{R}^n$ $(n\geq 3)$ be a convex polytope containing the origin in its interior. Let $\mbox{vol}_{n-2} \big( \mbox{relbd} ( P\cap\lbrace t\xi + \xi^\perp \rbrace ) \big)$ denote the $(n-2)$-dimensional volume of the relative boundary of $P\cap\lbrace t\xi + \xi^\perp \rbrace$ for $t\in\mathbb{R}$, $\xi\in S^{n-1}$. We prove the following: if \begin{align*} \mbox{vol}_{n-2} \Big( \mbox{relbd} \big( P\cap\xi^\perp \big) \Big) = \max_{t\in\mathbb{R}} \mbox{vol}_{n-2} \Big( \mbox{relbd} \big( P\cap\lbrace t\xi + \xi^\perp \rbrace \big) \Big) \end{align*} for all $\xi\in S^{n-1}$, then $P = -P$. Our result gives a partial affirmative answer to a conjecture by Makai, Martini, and \'Odor.

Mathematics; Functional analysis; Convex and discrete geometry

video/mp4

Author affiliation: University of Alberta

2018-09-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/67249

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/