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arXiv · 2003.07511

The Lemmens-Seidel conjecture and forbidden subgraphs

Meng-Yue Cao·Jack H·Koolen·Yen-Chi Roger Lin·Wei-Hsuan Yu
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Abstract

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

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Meng-Yue Cao, Jack H, Koolen, Yen-Chi Roger Lin, Wei-Hsuan Yu. 2020-03-17. The Lemmens-Seidel conjecture and forbidden subgraphs. https://arxiv.org/abs/2003.07511

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