English

Friezes over $\mathbb Z[\sqrt{2}]$

Combinatorics 2025-07-30 v2

Abstract

A frieze on a polygon is a map from the diagonals of the polygon to an integral domain which respects the Ptolemy relation. Conway and Coxeter previously studied positive friezes over Z\mathbb{Z} and showed that they are in bijection with triangulations of a polygon. We extend their work by studying friezes over Z[2]\mathbb Z[\sqrt{2}] and their relationships to dissections of polygons. We largely focus on the characterization of unitary friezes that arise from dissecting a polygon into triangles and quadrilaterals. We identify a family of dissections that give rise to unitary friezes and conjecture that this gives a complete classification of dissections which admit a unitary frieze.

Cite

@article{arxiv.2307.00440,
  title  = {Friezes over $\mathbb Z[\sqrt{2}]$},
  author = {Esther Banaian and Libby Farrell and Amy Tao and Kayla Wright and Joy Zhichun Zhang},
  journal= {arXiv preprint arXiv:2307.00440},
  year   = {2025}
}
R2 v1 2026-06-28T11:19:52.653Z