ABSTRACT

Our choice of topics in this chapter is governed by an interest in extending to digraphs some of the themes of earlier chapters. We first note that the four standard products can be interpreted as products on digraphs. Then we develop properties of connectedness, prime factorization, and cancellation. For the lexicographic product, these issues (as well as that of commutativity) are intimately tied to transitive tournaments, and one section is devoted to this.