نتایج جستجو برای: total roman domination

تعداد نتایج: 819671  

2007
Mehdi Hassankhani Nader Jafari Rad N. Jafari Rad

A graph G with no isolated vertex is total domination vertex critical if for any vertex v of G that is not adjacent to a vertex of degree one, the total domination number of G− v is less than the total domination number of G. We call these graphs total domination critical or just γt-critical. If such a graph G has total domination number k, we call it k-γt-critical. We study an open problem of ...

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 $D$....

Journal: :Discrete Applied Mathematics 2017

Journal: :Bulletin of the Iranian Mathematical Society 2019

Journal: :Australasian J. Combinatorics 2010
Nader Jafari Rad

A graph G with no isolated vertex is total domination bicritical if the removal of any pair of vertices, whose removal does not produce an isolated vertex, decreases the total domination number. In this paper we study properties of total domination bicritical graphs, and give several characterizations.

Journal: :Electr. J. Comb. 2017
Jernej Azarija Michael A. Henning Sandi Klavzar

Using hypergraph transversals it is proved that γt(Qn+1) = 2γ(Qn), where γt(G) and γ(G) denote the total domination number and the domination number of G, respectively, and Qn is the n-dimensional hypercube. More generally, it is shown that if G is a bipartite graph, then γt(G K2) = 2γ(G). Further, we show that the bipartiteness condition is essential by constructing, for any k > 1, a (non-bipa...

Journal: :Discussiones Mathematicae Graph Theory 2015
Diana Avella-Alaminos Magda Dettlaff Magdalena Lemanska Rita Zuazua

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...

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