Atapour, M.; Norouzian, S.; Sheikholeslami, S.M.; Volkmann, L.
(Algebra and Discrete Mathematics, 2017)
Let D=(V,A) be a finite simple directed graph (shortly digraph). A function f:V⟶{−1,1} is called a twin signed dominating function (TSDF) if f(N⁻[v])≥1 and f(N⁺[v])≥1 for each vertex v∈V. The twin signed domination number ...