Abstract
LetX n be the set ofn ×n symmetric matrices over a finite fieldF q, whereq is a power of an odd prime. ForS 1,S 2 εX n , we define (S 1,S 2) εR 0 iffS 1 =S 2; (S 1,S 2) εR (r,ξ) iffS 1 -S 2 is congruent to
where ξ = 1 orz,z being a fixed non-square element ofF q . ThenX n = (X n , {R 0,R (r,ξ) | 1 ≤r ≤n, ξ = 1 orz}) is a non-symmetric association scheme of class 2n onX n . The parameters ofX n have been computed. And we also prove thatX n is commutative.
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Huo, Y., Wan, Z. Non-symmetric association schemes of symmetric matrices. Acta Mathematicae Applicatae Sinica 9, 236–255 (1993). https://doi.org/10.1007/BF02032918
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DOI: https://doi.org/10.1007/BF02032918