Twin domination and twin irredundance in digraphs
S. Arumugam, Karam Ebadi, L. Sathikala · Applicable Analysis and Discrete Mathematics · 2013
Let D = (V,A) be a digraph. A subset S of V is called a twin dominating set of D if for every vertex v ? V ? S, there exist vertices u1, u2 ? S ( u1 and u2 may coincide) such that (v, u1) and (u2, v) are arcs in D. The minimum cardinality of a twin dominating set in D is called the twin domination number of D and is denoted by ?*(D). In this paper we present several basic results on these and other related parameters.