Geodesic
Trace, Symmetry and Orthogonality
Canadian mathematical bulletin, Tome 37 (1994) no. 4, pp. 461-467

Voir la notice de l'article provenant de la source Cambridge University Press

Does there exist a circulant conference matrix of order > 2? When is there a symmetric Hadamard matrix with constant diagonal? How many pairwise disjoint, amicable weighing matrices of order n can there be? These are questions concerning which the trace function gives a great deal of insight. We offer easy proofs of the known solutions to the first two, the first being new, and develop new results regarding the latter question. It is shown that there are 2t disjoint amicable weighing matrices of order 2tp, where p is odd, and that this is an upper bound for t ≤ 1. An even stronger bound is obtained for certain cases.
DOI : 10.4153/CMB-1994-067-1
Mots-clés : Primary: 05B20, secondary: 15A15, 05C50 
Craigen, R. Trace, Symmetry and Orthogonality. Canadian mathematical bulletin, Tome 37 (1994) no. 4, pp. 461-467. doi: 10.4153/CMB-1994-067-1
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