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Wyszukujesz frazę "Rad, Nader" wg kryterium: Autor


Tytuł:
On the Complexity of Reinforcement in Graphs
Autorzy:
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/31340751.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination
total domination
total restrained domination
p- domination
k-rainbow domination
reinforcement
NP-hard
Opis:
We show that the decision problem for p-reinforcement, p-total rein- forcement, total restrained reinforcement, and k-rainbow reinforcement are NP-hard for bipartite graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 877-887
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Roman bondage in graphs
Autorzy:
Rad, Nader
Volkmann, Lutz
Powiązania:
https://bibliotekanauki.pl/articles/743601.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination
Roman domination
Roman bondage number
Opis:
A Roman dominating function on a graph G is a function f:V(G) → {0,1,2} satisfying the condition that every vertex u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) = 2. The weight of a Roman dominating function is the value $f(V(G)) = ∑_{u ∈ V(G)}f(u)$. The Roman domination number, $γ_R(G)$, of G is the minimum weight of a Roman dominating function on G. In this paper, we define the Roman bondage $b_R(G)$ of a graph G with maximum degree at least two to be the minimum cardinality of all sets E' ⊆ E(G) for which $γ_R(G -E') > γ_R(G)$. We determine the Roman bondage number in several classes of graphs and give some sharp bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 4; 763-773
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fair Domination Number in Cactus Graphs
Autorzy:
Hajian, Majid
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/31343422.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
fair domination
cactus graph
unicyclic graph
Opis:
For k ≥ 1, a k-fair dominating set (or just kFD-set) in a graph G is a dominating set S such that |N(v) ∩ S| = k for every vertex v ∈ V \ S. The k-fair domination number of G, denoted by fdk(G), is the minimum cardinality of a kFD-set. A fair dominating set, abbreviated FD-set, is a kFD-set for some integer k ≥ 1. The fair domination number, denoted by fd(G), of G that is not the empty graph, is the minimum cardinality of an FD-set in G. In this paper, aiming to provide a particular answer to a problem posed in [Y. Caro, A. Hansberg and M.A. Henning, Fair domination in graphs, Discrete Math. 312 (2012) 2905–2914], we present a new upper bound for the fair domination number of a cactus graph, and characterize all cactus graphs G achieving equality in the upper bound of fd1(G).
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 489-503
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Progress on the Double Roman Domination in Graphs
Autorzy:
Rad, Nader Jafari
Rahbani, Hadi
Powiązania:
https://bibliotekanauki.pl/articles/31343730.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination
double Roman domination
Opis:
For a graph $ G = (V,E) $, a double Roman dominating function (or just DRDF) is a function $ f : V \rightarrow {0, 1, 2, 3} $ having the property that if $ f(v) = 0 $ for a vertex $ v $, then $ v $ has at least two neighbors assigned 2 under $ f $ or one neighbor assigned 3 under $ f $, and if $ f(v) = 1 $, then vertex $ v $ must have at least one neighbor $ w $ with $ f(w) \ge 2 $. The weight of a DRDF $f$ is the sum $f(V) = \Sigma_{ v \in V } f(v) $, and the minimum weight of a DRDF on $G$ is the double Roman domination number of $G$, denoted by $ \gamma_{dR} (G) $. In this paper, we derive sharp upper and lower bounds on $ \gamma_{dR} (G) + \gamma_{dR} ( \overline{G} ) $ and also $ \gamma_{dR} (G ) \gamma_{dR} ( \overline{G} ) $, where $ \overline{G} $ is the complement of graph $G$. We also show that the decision problem for the double Roman domination number is NP- complete even when restricted to bipartite graphs and chordal graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 41-53
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fair Total Domination Number in Cactus Graphs
Autorzy:
Hajian, Majid
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/32083904.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
fair total domination
cactus graph
Opis:
For k ≥ 1, a k-fair total dominating set (or just kFTD-set) in a graph G is a total dominating set S such that |N(v) ∩ S| = k for every vertex v ∈ V\S. The k-fair total domination number of G, denoted by ftdk(G), is the minimum cardinality of a kFTD-set. A fair total dominating set, abbreviated FTD-set, is a kFTD-set for some integer k ≥ 1. The fair total domination number of a nonempty graph G, denoted by ftd(G), of G is the minimum cardinality of an FTD-set in G. In this paper, we present upper bounds for the 1-fair total domination number of cactus graphs, and characterize cactus graphs achieving equality for the upper bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 647-664
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounds on the Double Italian Domination Number of a Graph
Autorzy:
Azvin, Farzaneh
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/32222552.pdf
Data publikacji:
2022-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Italian domination
double Italian domination
probabilistic methods
Opis:
For a graph G, a Roman {3}-dominating function is a function f : V → {0, 1, 2, 3} having the property that for every vertex u ∈ V, if f(u) ∈ {0, 1}, then f(N[u]) ≥ 3. The weight of a Roman {3}-dominating function is the sum w(f) = f(V) = Σv∈V f(v), and the minimum weight of a Roman {3}-dominating function is the Roman {3}-domination number, denoted by γ{R3}(G). In this paper, we present a sharp lower bound for the double Italian domination number of a graph, and improve previous bounds given in [D.A. Mojdeh and L. Volkmann, Roman {3}-domination (double Italian domination), Discrete Appl. Math. 283 (2022) 555–564]. We also present a probabilistic upper bound for a generalized version of double Italian domination number of a graph, and show that the given bound is asymptotically best possible.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 4; 1129-1137
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Algorithmic Aspects of the Independent 2-Rainbow Domination Number and Independent Roman {2}-Domination Number
Autorzy:
Poureidi, Abolfazl
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/32312036.pdf
Data publikacji:
2022-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
independent 2-rainbow dominating function
independent Roman {2}-dominating function
algorithm
3-SAT
Opis:
A 2-rainbow dominating function (2RDF) of a graph $G$ is a function $g$ from the vertex set $V (G)$ to the family of all subsets of $ \{1, 2\}$ such that for each vertex $v$ with $g(v) =\emptyset $ we have \( \bigcup_{u∈N(v)} g(u) = \{ 1, 2 \} \). The minimum of $ g(V (G)) = \Sigma_{v \in V (G)} |g(v)| $ over all such functions is called the 2-rainbow domination number. A 2RDF $g$ of a graph $G$ is independent if no two vertices assigned non empty sets are adjacent. The independent 2-rainbow domination number is the minimum weight of an independent 2RDF of $G$. A Roman {2}-dominating function (R2DF) $ f : V \rightarrow \{ 0, 1, 2 \} $ of a graph $G = (V, E)$ has the property that for every vertex $ v \in V$ with $f(v) = 0$ either there is $ u \in N(v)$ with $f(u) = 2$ or there are $x, y \in N(v)$ with $f(x) = f(y) = 1$. The weight of $f$ is the sum $f(V) = \Sigma_{v \in V} f(v) $. An R2DF $f$ is called independent if no two vertices assigned non-zero values are adjacent. The independent Roman {2}-domination number is the minimum weight of an independent R2DF on $G$. We first show that the decision problem for computing the independent 2-rainbow (respectively, independent Roman {2}-domination) number is NP-complete even when restricted to planar graphs. Then, we give a linear algorithm that computes the independent 2-rainbow domination number as well as the independent Roman {2}-domination number of a given tree, answering problems posed in [M. Chellali and N. Jafari Rad, Independent 2-rainbow domination in graphs, J. Combin. Math. Combin. Comput. 94 (2015) 133–148] and [A. Rahmouni and M. Chellali, Independent Roman {2}-domination in graphs, Discrete Appl. Math. 236 (2018) 408–414]. Then, we give a linear algorithm that computes the independent 2-rainbow domination number of a given unicyclic graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 3; 709-726
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strong Equality Between the Roman Domination and Independent Roman Domination Numbers in Trees
Autorzy:
Chellali, Mustapha
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/30146596.pdf
Data publikacji:
2013-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination
independent Roman domination
strong equality
trees
Opis:
A Roman dominating function (RDF) on a graph $G = (V,E)$ is a function $ f : V \rightarrow {0, 1, 2} $ satisfying the condition that every vertex $ u $ for which $ f(u) = 0 $ is adjacent to at least one vertex $v$ for which $f(v) = 2$. The weight of an RDF is the value $ f(V (G)) = \Sigma_{u \in V (G) } f(u) $. An RDF $f$ in a graph $G$ is independent if no two vertices assigned positive values are adjacent. The Roman domination number $ \gamma_R (G) $ (respectively, the independent Roman domination number $ i_R(G) $) is the minimum weight of an RDF (respectively, independent RDF) on $G$. We say that $ \gamma_R(G)$ strongly equals $ i_R(G)$, denoted by $ \gamma_R (G) \equiv i_R(G)$, if every RDF on $G$ of minimum weight is independent. In this paper we provide a constructive characterization of trees $T$ with $ \gamma_R(T) \equiv i_R(T) $.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 2; 337-346
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounds on the Locating Roman Domination Number in Trees
Autorzy:
Jafari Rad, Nader
Rahbani, Hadi
Powiązania:
https://bibliotekanauki.pl/articles/16647912.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination number
locating domination number
locating Roman domination number
tree
Opis:
A Roman dominating function (or just RDF) on a graph G = (V, E) is a function f : V → {0, 1, 2} satisfying the condition that every vertex u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) = 2. The weight of an RDF f is the value f(V (G)) = ∑u∈V(G) f(u). An RDF f can be represented as f = (V0, V1, V2), where Vi = {v ∈ V : f(v) = i} for i = 0, 1, 2. An RDF f = (V0, V1, V2) is called a locating Roman dominating function (or just LRDF) if N(u) ∩ V2 ≠ N(v) ∩ V2 for any pair u, v of distinct vertices of V0. The locating Roman domination number $\gamma _R^L (G)$ is the minimum weight of an LRDF of G. In this paper, we study the locating Roman domination number in trees. We obtain lower and upper bounds for the locating Roman domination number of a tree in terms of its order and the number of leaves and support vertices, and characterize trees achieving equality for the bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 49-62
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On The Roman Domination Stable Graphs
Autorzy:
Hajian, Majid
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/31341613.pdf
Data publikacji:
2017-11-27
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination number
bound
Opis:
A Roman dominating function (or just RDF) on a graph $ G = (V,E) $ is a function $ f : V \rightarrow \{ 0, 1, 2 \} $ satisfying the condition that every vertex $u$ for which $f(u) = 0$ is adjacent to at least one vertex $v$ for which $f(v) = 2$. The weight of an RDF $f$ is the value $f(V (G)) = \Sigma_{ u \in V(G) } f(u) $. The Roman domination number of a graph $G$, denoted by $ \gamma_R (G)$, is the minimum weight of a Roman dominating function on $G$. A graph $G$ is Roman domination stable if the Roman domination number of $G$ remains unchanged under removal of any vertex. In this paper we present upper bounds for the Roman domination number in the class of Roman domination stable graphs, improving bounds posed in [V. Samodivkin, Roman domination in graphs: the class $ R_{UV R} $, Discrete Math. Algorithms Appl. 8 (2016) 1650049].
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 4; 859-871
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounds on the Locating-Domination Number and Differentiating-Total Domination Number in Trees
Autorzy:
Rad, Nader Jafari
Rahbani, Hadi
Powiązania:
https://bibliotekanauki.pl/articles/31342324.pdf
Data publikacji:
2018-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
locating-dominating set
differentiating-total dominating set
tree
Opis:
A subset $S$ of vertices in a graph $G = (V,E)$ is a dominating set of $G$ if every vertex in $V − S$ has a neighbor in $S$, and is a total dominating set if every vertex in $V$ has a neighbor in $S$. A dominating set $S$ is a locating-dominating set of $G$ if every two vertices $ x, y \in V − S$ satisfy $N(x) \cap S \ne N(y) \cap S$. The locating-domination number $ \gamma_L (G) $ is the minimum cardinality of a locating-dominating set of $G$. A total dominating set $S$ is called a differentiating-total dominating set if for every pair of distinct vertices $u$ and $v$ of $G$, $ N[u] \cap S \ne N[v] \cap S $. The minimum cardinality of a differentiating-total dominating set of $G$ is the differentiating-total domination number of $G$, denoted by $ \gamma_t^D (G) $. We obtain new upper bounds for the locating-domination number, and the differentiating-total domination number in trees. Moreover, we characterize all trees achieving equality for the new bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 2; 455-462
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounds on the Locating Roman Domination Number in Trees
Autorzy:
Jafari Rad, Nader
Rahbani, Hadi
Powiązania:
https://bibliotekanauki.pl/articles/31342446.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination number
locating domination number
locating Roman domination number
tree
Opis:
A Roman dominating function (or just RDF) on a graph $ G = (V, E) $ is a function $ f : V \rightarrow \{ 0, 1, 2 \} $ satisfying the condition that every vertex $u$ for which $ f(u) = 0$ is adjacent to at least one vertex $v$ for which $f(v) = 2$. The weight of an RDF $f$ is the value $ f(V (G)) = \Sigma_{ u \in V (G) } f(u) $. An RDF $f$ can be represented as $ f = (V_0, V_1, V_2) $, where $ V_i = \{ v \in V : f(v) = i \} $ for $ i = 0, 1, 2 $. An RDF $ f = (V_0, V_1, V_2) $ is called a locating Roman dominating function (or just LRDF) if $ N(u) \cap V_2 \ne N(v) \cap V_2 $ for any pair $u$, $v$ of distinct vertices of $ V_0 $. The locating Roman domination number $ \gamma_R^L (G) $ is the minimum weight of an LRDF of $G$. In this paper, we study the locating Roman domination number in trees. We obtain lower and upper bounds for the locating Roman domination number of a tree in terms of its order and the number of leaves and support vertices, and characterize trees achieving equality for the bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 49-62
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on the Fair Domination Number in Outerplanar Graphs
Autorzy:
Hajian, Majid
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/31348125.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
fair domination
outerplanar graph
unicyclic graph
Opis:
For k ≥ 1, a k-fair dominating set (or just kFD-set), in a graph G is a dominating set S such that |N(v) ∩ S| = k for every vertex v ∈ V − S. The k-fair domination number of G, denoted by fdk(G), is the minimum cardinality of a kFD-set. A fair dominating set, abbreviated FD-set, is a kFD-set for some integer k ≥ 1. The fair domination number, denoted by fd(G), of G that is not the empty graph, is the minimum cardinality of an FD-set in G. In this paper, we present a new sharp upper bound for the fair domination number of an outerplanar graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 1085-1093
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the intersection graphs of ideals of direct product of rings
Autorzy:
Rad, Nader
Jafari, Sayyed
Ghosh, Shamik
Powiązania:
https://bibliotekanauki.pl/articles/729199.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
ideal
direct sum
intersection graph
Eulerian
Hamiltonian
Opis:
In this paper we first calculate the number of vertices and edges of the intersection graph of ideals of direct product of rings and fields. Then we study Eulerianity and Hamiltonicity in the intersection graph of ideals of direct product of commutative rings.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2014, 34, 2; 191-201
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of cubic graphs $G$ with $ir_t(G)=IR_t(G)=2$
Autorzy:
Eslahchi, Changiz
Haghi, Shahab
Jafari Rad, Nader
Powiązania:
https://bibliotekanauki.pl/articles/30148358.pdf
Data publikacji:
2014-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
total domination
total irredundance
cubic
Opis:
A subset $S$ of vertices in a graph $G$ is called a total irredundant set if, for each vertex $v$ in $G$, $v$ or one of its neighbors has no neighbor in $S −{v}$. The total irredundance number, $ir(G)$, is the minimum cardinality of a maximal total irredundant set of $G$, while the upper total irredundance number, $IR(G)$, is the maximum cardinality of a such set. In this paper we characterize all cubic graphs $G$ with $ir_t(G) = IR_t(G) = 2$.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 3; 559-565
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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