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Wyszukujesz frazę "domination number" wg kryterium: Temat


Tytuł:
Weak signed Roman k-domination in digraphs
Autorzy:
Volkmann, Lutz
Powiązania:
https://bibliotekanauki.pl/articles/29519480.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
digraph
weak signed Roman k-dominating function
weak signed Roman k-domination number
signed Roman k-dominating function
signed Roman k-domination number
Opis:
Let $ k ≥ 1 $ be an integer, and let $ D $ be a finite and simple digraph with vertex set $ V (D) $. A weak signed Roman k-dominating function (WSRkDF) on a digraph $ D $ is a function $ f : V (D) → {−1, 1, 2} $ satisfying the condition that $ \Sigma_{x∈N^−[v]} f(x) ≥ k $ for each v ∈ V (D), where $ N^− [v] $ consists of $ v $ and all vertices of $ D $ from which arcs go into $ v $. The weight of a WSRkDF $ f $ is $ w(f) = \Sigma_{v∈V} (D) f(v) $. The weak signed Roman k-domination number $ \gamma_{wsR}^k (D) $ is the minimum weight of a WSRkDF on $ D $. In this paper we initiate the study of the weak signed Roman k-domination number of digraphs, and we present different bounds on $ \gamma_{wsR}^k (D) $. In addition, we determine the weak signed Roman k-domination number of some classes of digraphs. Some of our results are extensions of well-known properties of the weak signed Roman domination number $ \gamma_{wsR} (D) = \gamma_{wsR}^1 (D) $ and the signed Roman k-domination number $ \gamma_{sR}^k (D) $.
Źródło:
Opuscula Mathematica; 2024, 44, 2; 285-296
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On minimum intersections of certain secondary dominating sets in graphs
Autorzy:
Kosiorowska, Anna
Michalski, Adrian
Włoch, Iwona
Powiązania:
https://bibliotekanauki.pl/articles/29519420.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
dominating set
2-dominating set
(1, 2)-dominating set
proper (1, 2)-dominating set
domination number
(1,2)-intersection index
Opis:
In this paper we consider secondary dominating sets, also named as (1,k)-dominating sets, introduced by Hedetniemi et al. in 2008. In particular, we study intersections of the (1, 1)-dominating sets and proper (1, 2)-dominating sets. We introduce (1,2̅)-intersection index as the minimum possible cardinality of such intersection and determine its value for some classes of graphs.
Źródło:
Opuscula Mathematica; 2023, 43, 6; 813-827
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Classification of Cactus Graphs According to their Domination Number
Autorzy:
Hajian, Majid
Henning, Michael A.
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/32315639.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination number
lower bounds
cycles
cactus graphs
Opis:
A set S of vertices in a graph G is a dominating set of G if every vertex not in S is adjacent to some vertex in S. The domination number, γ(G), of G is the minimum cardinality of a dominating set of G. The authors proved in [A new lower bound on the domination number of a graph, J. Comb. Optim. 38 (2019) 721–738] that if G is a connected graph of order n ≥ 2 with k ≥ 0 cycles and ℓ leaves, then γ(G) ≥ ⌈(n − ℓ + 2 − 2k)/3⌉. As a consequence of the above bound, γ(G) = (n − ℓ + 2(1 − k) + m)/3 for some integer m ≥ 0. In this paper, we characterize the class of cactus graphs achieving equality here, thereby providing a classification of all cactus graphs according to their domination number.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 613-626
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Further Results on Packing Related Parameters in Graphs
Autorzy:
Mojdeh, Doost Ali
Samadi, Babak
Yero, Ismael G.
Powiązania:
https://bibliotekanauki.pl/articles/32361731.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
packing number
open packing number
independence number
Nordhaus-Gaddum inequality
total domination number
Opis:
Given a graph G = (V, E), a set B ⊆ V (G) is a packing in G if the closed neighborhoods of every pair of distinct vertices in B are pairwise disjoint. The packing number ρ(G) of G is the maximum cardinality of a packing in G. Similarly, open packing sets and open packing number are defined for a graph G by using open neighborhoods instead of closed ones. We give several results concerning the (open) packing number of graphs in this paper. For instance, several bounds on these packing parameters along with some Nordhaus-Gaddum inequalities are given. We characterize all graphs with equal packing and independence numbers and give the characterization of all graphs for which the packing number is equal to the independence number minus one. In addition, due to the close connection between the open packing and total domination numbers, we prove a new upper bound on the total domination number γt(T) for a tree T of order n ≥ 2 improving the upper bound γt(T) ≤ (n + s)/2 given by Chellali and Haynes in 2004, in which s is the number of support vertices of T.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 333-348
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
γ-paired dominating graphs of cycles
Autorzy:
Eakawinrujee, Pannawat
Trakultraipruk, Nantapath
Powiązania:
https://bibliotekanauki.pl/articles/2048671.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
paired dominating graph
paired dominating set
paired-domination number
Opis:
A paired dominating set of a graph G is a dominating set whose induced subgraph contains a perfect matching. The paired domination number, denoted by γpr(G), is the minimum cardinality of a paired dominating set of G. A γpr(G)-set is a paired dominating set of cardinality γpr(G). The γ-paired dominating graph of G, denoted by PDγ(G), as the graph whose vertices are γpr(G)-sets. Two γpr(G)-sets D1 and D2 are adjacent in PDγ(G) if there exists a vertex u ∈ D1 and a vertex v /∈ D1 such that D2 = (D1 \ {u}) ∪ {v}. In this paper, we present the γ-paired dominating graphs of cycles.
Źródło:
Opuscula Mathematica; 2022, 42, 1; 31-54
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Block Graphs with Large Paired Domination Multisubdivision Number
Autorzy:
Mynhardt, Christina M.
Raczek, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/32083905.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
paired domination
domination subdivision number
domination multisubdivision number
block graph
Opis:
The paired domination multisubdivision number of a nonempty graph G, denoted by msdpr(G), is the smallest positive integer k such that there exists an edge which must be subdivided k times to increase the paired domination number of G. It is known that msdpr(G) ≤ 4 for all graphs G. We characterize block graphs with msdpr(G) = 4.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 665-684
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changing and Unchanging of the Domination Number of a Graph: Path Addition Numbers
Autorzy:
Samodivkin, Vladimir
Powiązania:
https://bibliotekanauki.pl/articles/32083856.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination number
path addition
Opis:
Given a graph $G=(V, E)$ and two its distinct vertices $u$ and $v$, the $(u, v)$-$P_k$-addition graph of $G$ is the graph $G_{u,v,k−2}$ obtained from disjoint union of $G$ and a path $P_k : x_0, x_1,...,x_{k−1}, k ≥ 2$, by identifying the vertices $u$ and $x_0$, and identifying the vertices $v$ and $x_{k−1}$. We prove that $\gamma(G) − 1 ≤ \gamma(G_{u,v,k})$ for all $k ≥ 1$, and $\gamma(G_{u,v,k})>\gamma(G)$ when $k ≥ 5$. We also provide necessary and sufficient conditions for the equality $\gamma(G_{u,v,k})=\gamma(G)$ to be valid for each pair $u, v ∈ V(G)$. In addition, we establish sharp upper and lower bounds for the minimum, respectively maximum, $k$ in a graph $G$ over all pairs of vertices $u$ and $v$ in $G$ such that the $(u, v)$-$P_k$-addition graph of $G$ has a larger domination number than $G$, which we consider separately for adjacent and non-adjacent pairs of vertices.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 365-379
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Domination Number, Independent Domination Number and 2-Independence Number in Trees
Autorzy:
Dehgardi, Nasrin
Sheikholeslami, Seyed Mahmoud
Valinavaz, Mina
Aram, Hamideh
Volkmann, Lutz
Powiązania:
https://bibliotekanauki.pl/articles/32083746.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
2-independence number
domination number
independent domination number
Opis:
For a graph $G$, let $\gamma(G)$ be the domination number, $i(G)$ be the independent domination number and $\beta_2(G)$ be the 2-independence number. In this paper, we prove that for any tree $T$ of order $n ≥ 2, 4\beta_2(T) − 3\gamma(T) ≥ 3i(T)$, and we characterize all trees attaining equality. Also we prove that for every tree $T$ of order \(n ≥ 2, i(T)≤\frac{3\beta_2(T)}{4}\), and we characterize all extreme trees.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 39-49
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Domination Number of Graphs with Minimum Degree Five
Autorzy:
Bujtás, Csilla
Powiązania:
https://bibliotekanauki.pl/articles/32222697.pdf
Data publikacji:
2021-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
dominating set
domination number
discharging method
Opis:
We prove that for every graph G on n vertices and with minimum degree five, the domination number γ(G) cannot exceed n/3. The proof combines an algorithmic approach and the discharging method. Using the same technique, we provide a shorter proof for the known upper bound 4n/11 on the domination number of graphs of minimum degree four.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 3; 763-777
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Independent Transversal Total Domination versus Total Domination in Trees
Autorzy:
Martínez, Abel Cabrera
Peterin, Iztok
Yero, Ismael G.
Powiązania:
https://bibliotekanauki.pl/articles/32083825.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
independent transversal total domination number
total domination number
independence number
trees
Opis:
A subset of vertices in a graph G is a total dominating set if every vertex in G is adjacent to at least one vertex in this subset. The total domination number of G is the minimum cardinality of any total dominating set in G and is denoted by γt(G). A total dominating set of G having nonempty intersection with all the independent sets of maximum cardinality in G is an independent transversal total dominating set. The minimum cardinality of any independent transversal total dominating set is denoted by γtt(G). Based on the fact that for any tree T, γt(T) ≤ γtt(T) ≤ γt(T) + 1, in this work we give several relationships between γtt(T) and γt(T) for trees T which are leading to classify the trees which are satisfying the equality in these bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 213-224
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Grundy Total Domination Number in Product Graphs
Autorzy:
Brešar, Boštjan
Bujtás, Csilla
Gologranc, Tanja
Klavžar, Sandi
Košmrlj, Gašper
Marc, Tilen
Patkós, Balázs
Tuza, Zsolt
Vizer, Máté
Powiązania:
https://bibliotekanauki.pl/articles/32083828.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
total domination
Grundy total domination number
graph product
Opis:
A longest sequence $(v_1, . . ., v_k)$ of vertices of a graph $G$ is a Grundy total dominating sequence of $G$ if for all $i$, \(N(υ_i)\backslash\bigcup_{j=1}^{i-1}N(υ_j)≠∅\). The length $k$ of the sequence is called the Grundy total domination number of $G$ and denoted $\gamma_{gr}^t(G)$. In this paper, the Grundy total domination number is studied on four standard graph products. For the direct product we show that $\gamma_{gr}^t(G×H)≥\gamma_{gr}^t(G)\gamma_{gr}^t(H)$, conjecture that the equality always holds, and prove the conjecture in several special cases. For the lexicographic product we express $\gamma_{gr}^t(G∘H)$ in terms of related invariant of the factors and find some explicit formulas for it. For the strong product, lower bounds on $\gamma_{gr}^t(G⊠H)$ are proved as well as upper bounds for products of paths and cycles. For the Cartesian product we prove lower and upper bounds on the Grundy total domination number when factors are paths or cycles.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 225-247
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on the outer-independent double Italian domination number
Autorzy:
Volkman, Lutz
Powiązania:
https://bibliotekanauki.pl/articles/2051048.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
double Italian domination number
outer-independent double Italian domination number
Nordhaus-Gaddum bound
Opis:
Let $G$ be a graph with vertex set $V(G)$. If $u \in V(G)$, then $N[u]$ is the closed neighborhood of $u$. An outer-independent double Italian dominating function (OIDIDF) on a graph $G$ is a function $ƒ : V(G) \rightarrow \{0, 1, 2, 3\}$ such that if $ƒ (v) \in \{0, 1\}$ for a vertex $v \in V(G)$, then $\Sigma_{x \in N[v]} f(x) \geq 3$, and the set ${u \in V(G) : f (u) = 0}$ is independent. The weight of an OIDIDF $f$ is the sum $\Sigma_{v \in V(G)} f(v)$. The outer-independent double Italian domination number $\gamma_{oidI}(G)$ equals the minimum weight of an OIDIDF on G. In this paper we present Nordhaus-Gaddum type bounds on the outer-independent double Italian domination number which improved corresponding results given in [F. Azvin, N. Jafari Rad, L. Volkmann, \textit{Bounds on the outer-independent double Italian domination number}, Commun. Comb. Optim. 6 (2021), 123-136]. Furthermore, we determine the outer-independent double Italian domination number of some families of graphs.
Źródło:
Opuscula Mathematica; 2021, 41, 2; 259-268
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Total 2-Rainbow Domination Numbers of Trees
Autorzy:
Ahangar, H. Abdollahzadeh
Amjadi, J.
Chellali, M.
Nazari-Moghaddam, S.
Sheikholeslami, S.M.
Powiązania:
https://bibliotekanauki.pl/articles/32083855.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
2-rainbow dominating function
2-rainbow domination number
total 2-rainbow dominating function
total 2-rainbow domination number
Opis:
A 2-rainbow dominating function (2RDF) of a graph $G = (V(G), E(G))$ is a function $f$ from the vertex set $V(G)$ to the set of all subsets of the set {1, 2} such that for every vertex $v ∈ V(G)$ with $f(v) = ∅$ the condition \(\bigcup_{u∈N(v)}f(u) = \{1, 2\}\) is fulfilled, where $N(v)$ is the open neighborhood of $v$. A total 2-rainbow dominating function $f$ of a graph with no isolated vertices is a 2RDF with the additional condition that the subgraph of $G$ induced by $\{v ∈ V (G) | f(v) ≠∅\}$ has no isolated vertex. The total 2-rainbow domination number, $\gamma_{tr2}(G)$, is the minimum weight of a total 2-rainbow dominating function of $G$. In this paper, we establish some sharp upper and lower bounds on the total 2-rainbow domination number of a tree. Moreover, we show that the decision problem associated with $\gamma_{tr2}(G)$ is NP-complete for bipartite and chordal graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 345-364
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on bipartite graphs whose [1, k]-domination number equal to their number of vertices
Autorzy:
Ghareghani, Narges
Peterin, Iztok
Sharifani, Pouyeh
Powiązania:
https://bibliotekanauki.pl/articles/256007.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
domination
[1, k]-domination number
[l,k]-total domination number
bipartite graphs
Opis:
A subset D of the vertex set V of a graph G is called an [1, k]-dominating set if every vertex from V — D is adjacent to at least one vertex and at most fc vertices of D. A [1, k]-dominating set with the minimum number of vertices is called a [formula]-set and the number of its vertices is the [1, k]-domination number [formula] of G. In this short note we show that the decision problem whether [formula] is an NP-hard problem, even for bipartite graphs. Also, a simple construction of a bipartite graph G of order n satisfying [formula] is given for every integer n ≥ (k + l)(2k + 3).
Źródło:
Opuscula Mathematica; 2020, 40, 3; 375-382
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounds on the Locating-Total Domination Number in Trees
Autorzy:
Wang, Kun
Ning, Wenjie
Lu, Mei
Powiązania:
https://bibliotekanauki.pl/articles/31867549.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
tree
total dominating set
locating-total dominating set
locating-total domination number
Opis:
Given a graph $G = (V, E)$ with no isolated vertex, a subset $S$ of $V$ is called a total dominating set of $G$ if every vertex in $V$ has a neighbor in $S$. A total dominating set $S$ is called a locating-total dominating set if for each pair of distinct vertices $u$ and $v$ in $V \ S, N(u) ∩ S ≠ N(v) ∩ S$. The minimum cardinality of a locating-total dominating set of $G$ is the locating-total domination number, denoted by $γ_t^L(G)$. We show that, for a tree $T$ of order $n ≥ 3$ and diameter $d$, \(\frac{d+1}{2}≤γ_t^L(T)≤n−\frac{d−1}{2}\), and if $T$ has $l$ leaves, $s$ support vertices and $s_1$ strong support vertices, then \(γ_t^L(T)≥max\Big\{\frac{n+l−s+1}{2}−\frac{s+s_1}{4},\frac{2(n+1)+3(l−s)−s_1}{5}\Big\}\). We also characterize the extremal trees achieving these bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 25-34
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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