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Algorithmic aspects of 2-secure domination in graphs
Let G ( V , E ) be a simple, connected and undirected graph. A dominating set S ⊆ V is called a 2- secure dominating set (2-SDS) in G , if for each pair of distinct vertices v 1 , v 2 ∈ V there exists a pair of distinct vertices u 1 , u 2 ∈ S such that u 1 ∈ N [ v 1 ] , u 2 ∈ N [ v 2 ] and ( S \ {...
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Published in: | Journal of combinatorial optimization 2021-07, Vol.42 (1), p.56-70 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Let
G
(
V
,
E
) be a simple, connected and undirected graph. A dominating set
S
⊆
V
is called a 2-
secure dominating set
(2-SDS) in
G
, if for each pair of distinct vertices
v
1
,
v
2
∈
V
there exists a pair of distinct vertices
u
1
,
u
2
∈
S
such that
u
1
∈
N
[
v
1
]
,
u
2
∈
N
[
v
2
]
and
(
S
\
{
u
1
,
u
2
}
)
∪
{
v
1
,
v
2
}
is a dominating set in
G
. The size of a minimum 2-SDS in
G
is said to be 2-
secure domination number
denoted by
γ
2
s
(
G
)
. The 2-SDM problem is to check if an input graph
G
has a 2-SDS
S
, with
|
S
|
≤
k
, where
k
∈
Z
+
. It is proved that for bipartite graphs 2-SDM is NP-complete. In this paper, we prove that the 2-SDM problem is NP-complete for planar graphs and doubly chordal graphs, a subclass of chordal graphs. We reinforce the existing NP-complete result for bipartite graphs, by proving 2-SDM is NP-complete for some subclasses of bipartite graphs specifically, comb convex bipartite and star convex bipartite graphs. We prove that this problem is linear time solvable for bounded tree-width graphs. We also show that the 2-SDM is W[2]-hard even for split graphs. The M2SDS problem is to find a 2-SDS of minimum size in the given graph. We give a
Δ
+
1
-approximation algorithm for M2SDS, where
Δ
is the maximum degree of the given graph and prove that M2SDS cannot be approximated within
(
1
-
ϵ
)
ln
(
|
V
|
)
for any
ϵ
>
0
unless
N
P
⊆
D
T
I
M
E
(
|
V
|
O
(
log
log
|
V
|
)
)
. Finally, we prove that the M2SDS is APX-complete for graphs with
Δ
=
4
. |
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ISSN: | 1382-6905 1573-2886 |
DOI: | 10.1007/s10878-021-00739-9 |