Quasi-total Roman Domination in Graphs

[EN] A quasi-total Roman dominating function on a graph G=(V,E) is a function f:V ->{0,1,2}satisfying the following: Every vertex for which u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) = 2, and If x is an isolated vertex in the subgraph induced by the set of vertices labeled with 1 and 2, then f(x) = 1. The weight of a quasi-total Roman dominating function is the value omega(f) = f(V) = Sigma(u is an element of V) f(u). The minimum weight of a quasi-total Roman dominating function on a graph G is called the quasi-total Roman domination number of G. We introduce the quasi-total Roman domination number of graphs in this article, and begin the study of its combinatorial and computational properties.Cabrera García, S.; Cabrera Martínez, A.; Yero, IG. (2019). Quasi-total Roman Domination in Graphs. Results in Mathematics. 74(4):1-18. https://doi.org/10.1007/s00025-019-1097-5S11874

Total Domination Multisubdivision Number of a Graph

The domination multisubdivision number of a nonempty graph G was defined in [3] as the minimum positive integer k such that there exists an edge which must be subdivided k times to increase the domination number of G. Similarly we define the total domination multisubdivision number msdγt (G) of a graph G and we show that for any connected graph G of order at least two, msdγt (G) ≤ 3. We show that for trees the total domination multisubdi- vision number is equal to the known total domination subdivision number. We also determine the total domination multisubdivision number for some classes of graphs and characterize trees T with msdγt (T) = 1