English

The Hexagonal Tiling Honeycomb

History and Overview 2024-12-03 v1 Algebraic Geometry Metric Geometry

Abstract

The hexagonal tiling honeycomb is a beautiful structure in 3-dimensional hyperbolic space. It is called {6,3,3} because each hexagon has 6 edges, 3 hexagons meet at each vertex in a Euclidean plane tiled by regular hexagons, and 3 such planes meet along each edge of this honeycomb. It also appears naturally in algebraic geometry. If E\mathbb{E} denotes the Eisenstein integers, the N\'eron-Severi group of the abelian surface C2/E2\mathbb{C}^2/\mathbb{E}^2 is isomorphic to the lattice h2(E)\mathfrak{h}_2(\mathbb{E}) consisting of 2×22 \times 2 hermitian matrices with Eisenstein integer entries. The points Ah2(E)A \in \mathfrak{h}_2(\mathbb{E}) with tr(A)>0\mathrm{tr}(A) \gt 0 and det(A)>0\det(A) \gt 0 come from ample line bundles on C2/E2\mathbb{C}^2/\mathbb{E}^2, and among these points, those with det(A)=1\det(A) = 1 correspond to principal polarizations. But these points are precisely the centers of the hexagons in the hexagonal tiling honeycomb!

Keywords

Cite

@article{arxiv.2412.00048,
  title  = {The Hexagonal Tiling Honeycomb},
  author = {John C. Baez},
  journal= {arXiv preprint arXiv:2412.00048},
  year   = {2024}
}

Comments

2 pages, figure by Roice Nelson

R2 v1 2026-06-28T20:17:20.696Z