Digraphs

Graph theory is a very popular area of discrete mathematics with not only numerous theoretical developments, but also countless applications to prac­ tical problems. As a research area, graph theory is still relatively young, but it is maturing rapidly with many deep results having been discovered over the last couple of decades. The theory of graphs can be roughly partitioned into two branches: the areas of undirected graphs and directed graphs (digraphs). Even though both areas have numerous i