Krein Parameters of Fiber-Commutative Coherent Configurations

Keiji Ito, Akihiro Munemasa

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


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.

Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalAlgebra Colloquium
Issue number1
Publication statusPublished - 2020 Mar 1


  • Krein condition
  • Krein parameter
  • absolute bound
  • association scheme
  • coherent configuration
  • generalized quadrangle


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