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