Roman dominating function} on a digraph $D$ with vertex set $V(D)$ is a labeling$fcolon V(D)to {0, 1, 2}$such that every vertex with label $0$ has an in-neighbor with label $2$. A set ${f_1,f_2,ldots,f_d}$ ofRoman dominating functions on $D$ with the property that $sum_{i=1}^d f_i(v)le 2$ for each $vin V(D)$,is called a {em Roman dominating family} (of functions) on $D$....

A subset S of vertices in a graph G is a global total dominating set, or just GTDS, if S is a total dominating set of both G and G. The global total domination number γgt(G) of G is the minimum cardinality of a GTDS of G. We present bounds for the global total domination number in graphs.

The global health agenda has been dominating the current global health policy debate. Furthermore, it has compelled countries to embrace strategies for tackling health inequalities in a wide range of public health areas. The article by Robert and colleagues highlights that although globalization has increased opportunities to share and spread ideas, there is still great asymmetry of power accor...

A defensive alliance in a graph is a set $S$ of vertices with the property that every vertex in $S$ has at most one moreneighbor outside of $S$ than it has inside of $S$. A defensive alliance $S$ is called global if it forms a dominating set. The global defensive alliance number of a graph $G$ is the minimum cardinality of a global defensive alliance in $G$. In this article we study the global ...

the global health agenda has been dominating the current global health policy debate. furthermore, it has compelled countries to embrace strategies for tackling health inequalities in a wide range of public health areas. the article by robert and colleagues highlights that although globalization has increased opportunities to share and spread ideas, there is still great asymmetry of power accor...

A Roman dominating function (RDF) on a digraph $D$ is a function $f: V(D)rightarrow {0,1,2}$ satisfying the condition that every vertex $v$ with $f(v)=0$ has an in-neighbor $u$ with $f(u)=2$. The weight of an RDF $f$ is the value $sum_{vin V(D)}f(v)$. The Roman domination number of a digraph $D$ is the minimum weight of an RDF on $D$. A set ${f_1,f_2,dots,f_d}$ of Roman dominating functions on ...

For any graph G = (V, E), D  V is a global dominating set if D dominates both G and its complement G . The global domination number g(G) of a graph G is the fewest number of vertices required of a global dominating set. In general, max{(G), (G )} ≤ g(G) ≤ (G)+(G ), where (G) and (G ) are the respective domination numbers of G and G . We show, when G is a planar graph, that g(G) ≤ max{...

Abstract: Let G=(V,E) be a graph and let f:V(G)→{0,1,2} be a function‎. ‎A vertex v is protected with respect to f‎, ‎if f(v)>0 or f(v)=0 and v is adjacent to a vertex of positive weight‎. ‎The function f is a co-Roman dominating function‎, ‎abbreviated CRDF if‎: ‎(i) every vertex in V is protected‎, ‎and (ii) each u∈V with positive weight has a neighbor v∈V with f(v)=0 such that the func...