Krein Parameters of Fiber-Commutative Coherent Configurations  

作　　者：Keiji Ito Akihiro Munemasa 

机构地区：[1]Research Center for Pure and Applied Mathematics,Graduate School of Information Sciences,Tohoku University,Sendai,Japan

出　　处：《Algebra Colloquium》2020年第1期1-10,共10页代数集刊（英文版）

摘　　要：For fiber-commutative coherent configurations,we show that Krein parameters can be defined essentially uniquely.As a consequence,the general Krein condition reduces to positive semidefiniteness of finitely many matrices determined by the parameters of a coherent configuration.We mention its implications in the coherent configuration defined by a generalized quadrangle.We also simplify the absolute bound using the matrices of Krein parameters.

关 键 词：coherent configuration association scheme Krein parameter Krein condition generalized quadrangle absolute bound 

分 类 号：O15[理学—数学]