AMS classifications: 05C50; 05E99;

AMS classifications: 05C50, 05E99;

2000 Mathematics Subject Classification: 05C50, 05E99;

AMS classification: 05E30

We show that the Hamming graph H(3; q) with diameter three is uniquely determined by its spectrum for q ¸ 36. Moreover, we show that for given integer D ¸ 2, any graph cospectral with the Hamming graph H(D; q) is locally the disjoint union of D copies of the complete graph of size q ¡ 1, for q...

In this and a sequel paper [10] we study combinatorial designs whose incidence matrix has two distinct singular values.These generalize 2-(v, k, É) designs, and include partial geometric designs and uniform multiplicative designs.Here we study the latter, which are precisely the nonsingular...

In this and an earlier paper [17] we study combinatorial designs whose incidence matrix has two distinct singular values.These generalize (v, k, ë) designs, and include uniform multiplicative designs and partial geometric designs.Here we study the latter, which are precisely the designs with...

AMS classification: 05C50;

2010 Mathematics Subject Classification: 05E30, 05C50;

AMS classifications; 05C50; 05E30;