Krein parameters and antipodal tight graphs with diameter 3 and 4

被引:30
|
作者
Jurisic, A
Koolen, J
机构
[1] IMFM, Nova Gorica, Slovenia
[2] Nova Gorica Polytech, Nova Gorica, Slovenia
[3] Univ Bielefeld, FSP, D-33501 Bielefeld, Germany
关键词
Krein parameters; distance-regular graphs; tight graphs; 1-homogeneous graphs; antipodal graphs; locally strongly-regular; Taylor graphs;
D O I
10.1016/S0012-365X(01)00082-6
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We determine which Krein parameters of nonbipartite antipodal distance-regular graphs of diameter 3 and 4 can vanish, and give combinatorial interpretations of their vanishing. We also study tight distance-regular graphs of diameter 3 and 4. In the case of diameter 3, tight graphs are precisely the Taylor graphs. In the case of antipodal distance-regular graphs of diameter 4, tight graphs are precisely the graphs for which the Krein parameter q(11)(4) vanishes. (C) 2002 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:181 / 202
页数:22
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