Equiangular lines in Euclidean spaces

被引:51
|
作者
Greaves, Gary [1 ]
Koolen, Jacobus H. [2 ]
Munemasa, Akihiro [1 ]
Szoellosi, Ferenc [1 ]
机构
[1] Tohoku Univ, Grad Sch Informat Sci, Res Ctr Pure & Appl Math, Sendai, Miyagi 9808579, Japan
[2] Univ Sci & Technol China, Sch Math Sci, Hefei 230026, Anhui, Peoples R China
关键词
Equiangular lines; Seidel matrix; Switching; Two-graph; HADAMARD-MATRICES; EULER GRAPHS; REPRESENTATIONS;
D O I
10.1016/j.jcta.2015.09.008
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We obtain several new results contributing to the theory of real equiangular line systems Among other things, we present a new general lower bound on the maximum number of equiangular lines in d dimensional Euclidean space; we describe the two-graphs on 12 vertices; and we investigate Seidel matrices with exactly three distinct eigenvalues. As a result, we improve on two long-standing upper bounds regarding the maximum number of equiangular lines in dimensions d = 14 and d = 16. Additionally, we prove the nonexistence of certain regular graphs with four eigenvalues, and correct some tables from the literature. (C) 2015 Elsevier Inc. All rights reserved.
引用
收藏
页码:208 / 235
页数:28
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