General constructions of c-Bhaskar Rao designs and the (c,λ) spectrum of a c-BRD(v,k,λ) Original Research Article

New constructions of Bhaskar Rao designs (BRDs) and new families of c-BRDs are given using the relationship of BRDs to other combinatorial structures. For example, we use different families and their properties in various ways to obtain natural signings of BIBDs in order to construct c-BRDs. We investigate the extreme possibilities for c relative to λ, and k relative to v, and prove the non-existence of an infinite series of designs. We also give a symmetricized version of Ehlichʹs Hadamard construction.