On planar sections of the dodecahedron

TL;DR

This paper investigates whether planar sections of the dodecahedron uniquely determine vertex subsets, finding that non-isometric subsets can share identical planar intersection statistics, revealing non-uniqueness in geometric tomography.

Contribution

It introduces a discrete analogue of biological microstructure analysis, demonstrating non-uniqueness in reconstructing 3D structures from planar intersection data.

Findings

Existence of non-isometric vertex subsets with identical planar statistics

Non-uniqueness of 3D polytopes based on intersection distributions

Analogy to classical non-uniqueness phenomena in geometric tomography

Abstract

In the analysis of three-dimensional biological microstructures such as organoids, microscopy frequently yields two-dimensional optical sections without access to their orientation. Motivated by the question of whether such random planar sections determine the underlying three-dimensional structure, we investigate a discrete analogue in which the ambient structure is the vertex set of a Platonic solid and the observed data are congruence classes of planar intersections. For the regular dodecahedron with vertex set $V$, we define the planar statistic of a subset $X\subseteq V$ of vertices as the distribution of isometry types of inclusions $\Pi\cap X \subseteq \Pi \cap V \subseteq V$, and ask whether this statistic determines $X$ up to isometry. We show that this is not the case: there exist two non-isometric $7$-element subsets with identical planar statistics. As a consequence, there exist two polytopes in $\mathbb R^3$, whose distribution of isometry classes of two-dimensional intersections is identical, while the polytopes are not themselves isometric. This result is an analogue of classical non-uniqueness phenomena in geometric tomography.