Article in volume
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Title:
Total Roman $\{2\}$-dominating functions in graphs
PDFSource:
Discussiones Mathematicae Graph Theory 42(3) (2022) 937-958
Received: 2019-10-29 , Revised: 2020-03-02 , Accepted: 2020-03-23 , Available online: 2020-04-18 , https://doi.org/10.7151/dmgt.2316
Abstract:
A Roman $\{2\}$-dominating function (R2F) is a function $f:V\rightarrow
\{0,1,2\}$ with the property that for every vertex $v\in V$ with $f(v)=0$
there is a neighbor $u$ of $v$ with $f(u)=2$, or there are two neighbors $x,y$
of $v$ with $f(x)=f(y)=1$. A total Roman $\{2\}$-dominating function (TR2DF)
is an R2F $f$ such that the set of vertices with $f(v)>0$ induce a subgraph
with no isolated vertices. The weight of a TR2DF is the sum of its function
values over all vertices, and the minimum weight of a TR2DF of $G$ is the
total Roman $\{2\}$-domination number $\gamma_{tR2}(G).$ In this paper, we
initiate the study of total Roman $\{2\}$-dominating functions, where properties
are established. Moreover, we present various bounds on the total Roman
$\{2\}$-domination number. We also show that the decision problem associated
with $\gamma_{tR2}(G)$ is NP-complete for bipartite and chordal graphs.
Moreover, we show that it is possible to compute this parameter in linear time
for bounded clique-width graphs (including trees).
Keywords:
Roman domination, Roman $\{2\}$-domination, total Roman $\{2\}$-domination
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