English

Similar sublattices of the root lattice $A_4$

Metric Geometry 2019-07-17 v2 Combinatorics

Abstract

Similar sublattices of the root lattice A4A_4 are possible, according to a result of Conway, Rains and Sloane, for each index that is the square of a non-zero integer of the form m2+mnn2m^2 + mn - n^2. Here, we add a constructive approach, based on the arithmetic of the quaternion algebra H(Q(5))\mathbb{H} (\mathbb{Q} (\sqrt{5})) and the existence of a particular involution of the second kind, which also provides the actual sublattices and the number of different solutions for a given index. The corresponding Dirichlet series generating function is closely related to the zeta function of the icosian ring.

Keywords

Cite

@article{arxiv.math/0702448,
  title  = {Similar sublattices of the root lattice $A_4$},
  author = {Michael Baake and Manuela Heuer and Robert V. Moody},
  journal= {arXiv preprint arXiv:math/0702448},
  year   = {2019}
}

Comments

17 pages, 1 figure; revised version with several additions and improvements