The -domatic number of a graph
Let be a positive integer, and let be a simple graph with vertex set . A of the graph is a subset of such that every vertex of is adjacent to at least vertices in . A of is a partition of into -dominating sets. The maximum number of dominating sets in a -domatic partition of is called the . In this paper, we present upper and lower bounds for the -domatic number, and we establish Nordhaus-Gaddum-type results. Some of our results extend those for the classical...