English

On planar sections of the dodecahedron

Metric Geometry 2026-01-29 v4

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 VV, we define the planar statistic of a subset XVX\subseteq V of vertices as the distribution of isometry types of inclusions ΠXΠVV\Pi\cap X \subseteq \Pi \cap V \subseteq V, and ask whether this statistic determines XX up to isometry. We show that this is not the case: there exist two non-isometric 77-element subsets with identical planar statistics. As a consequence, there exist two polytopes in R3\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.

Keywords

Cite

@article{arxiv.2511.12773,
  title  = {On planar sections of the dodecahedron},
  author = {Andreas Thom},
  journal= {arXiv preprint arXiv:2511.12773},
  year   = {2026}
}

Comments

10 pages, 75 figures, 2 tables; v3 minor update; v4 another minor update to the intro