Minus Domination Numbers of Directed Graphs
The concept of minus domination number of an undirected graph is transferred to directed graphs. Exact values are found for the directed cycle and particular types of tournaments. Furthermore, we present some lower bounds for minus domination number in terms of the order, the maximum degree, the maximum outdegree and the minimum outdegree of a directed graph.
W. S. Li and H. M. Xing, "Minus Domination Numbers of Directed Graphs", Advanced Materials Research, Vol. 267, pp. 334-337, 2011