Designs

Abstract

Most of the combinatorial objects studied in this book have been defined as systems satisfying certain conditions. The term “design” is reserved for a system ∧ = (V, f, E) with selection s such that $\overline s$ and $\overline {{s^ * }}$ are constant on some of the collections P_t(V) (t = 1,..., |V| − 1) and P_a(E) (a = 1,..., |E| − 1) respectively. The reader may wish before proceeding to review the properties of the functions $\overline s$ and $\overline {{s^ * }}$ in §IE.