Some results on λ-designs

Abstract

A λ-design as introduced by Ryser [3] is a (0, 1)-square matrix with constant column inner products but not all column sums equal. Ryser has shown such a matrix to have two row sums and he constructs an infinite family of λ-designs called H-designs. This paper does three things: (1) generalizes Ryser's H-design construction to an arbitrary (ν, k, λ)-configuration, (2) establishes some additional general properties of λ-designs, and (3) determines all 4-designs.