English

The Lemmens-Seidel conjecture and forbidden subgraphs

Combinatorics 2020-03-18 v1

Abstract

In this paper we show that the conjecture of Lemmens and Seidel of 1973 for systems of equiangular lines with common angle arccos(1/5)\arccos (1/5) is true. Our main tool is forbidden subgraphs for smallest Seidel eigenvalue 5-5.

Keywords

Cite

@article{arxiv.2003.07511,
  title  = {The Lemmens-Seidel conjecture and forbidden subgraphs},
  author = {Meng-Yue Cao and Jack H and Koolen and Yen-Chi Roger Lin and Wei-Hsuan Yu},
  journal= {arXiv preprint arXiv:2003.07511},
  year   = {2020}
}

Comments

28 pages, 2 tables, 6 figures

R2 v1 2026-06-23T14:16:54.376Z