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Wyszukujesz frazę "Nordhaus-Gaddum" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Generalised irredundance in graphs: Nordhaus-Gaddum bounds
Autorzy:
Cockayne, Ernest
Finbow, Stephen
Powiązania:
https://bibliotekanauki.pl/articles/744461.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
generalised irredundance
Nordhaus-Gaddum
Opis:
For each vertex s of the vertex subset S of a simple graph G, we define Boolean variables p = p(s,S), q = q(s,S) and r = r(s,S) which measure existence of three kinds of S-private neighbours (S-pns) of s. A 3-variable Boolean function f = f(p,q,r) may be considered as a compound existence property of S-pns. The subset S is called an f-set of G if f = 1 for all s ∈ S and the class of f-sets of G is denoted by $Ω_f(G)$. Only 64 Boolean functions f can produce different classes $Ω_f(G)$, special cases of which include the independent sets, irredundant sets, open irredundant sets and CO-irredundant sets of G. Let $Q_f(G)$ be the maximum cardinality of an f-set of G. For each of the 64 functions f, we establish sharp upper bounds for the sum $Q_f(G) + Q_f(G̅)$ and the product $Q_f(G)Q_f(G̅)$ in terms of n, the order of G.
Źródło:
Discussiones Mathematicae Graph Theory; 2004, 24, 1; 147-160
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on Roman Domination of Digraphs
Autorzy:
Chen, Xiaodan
Hao, Guoliang
Xie, Zhihong
Powiązania:
https://bibliotekanauki.pl/articles/31343785.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Roman domination number
domination number
digraph
Nordhaus-Gaddum
Opis:
A vertex subset $S$ of a digraph $D$ is called a dominating set of $D$ if every vertex not in $S$ is adjacent from at least one vertex in $S$. The domination number of a digraph $D$, denoted by $ \gamma(D) $, is the minimum cardinality of a dominating set of $D$. A Roman dominating function (RDF) on a digraph $D$ is a function $ f : V (D) \rightarrow {0, 1, 2} $ satisfying the condition that every vertex $v$ with $f(v) = 0$ has an in-neighbor $u$ with $f(u) = 2$. The weight of an RDF $f$ is the value $ \omega (f) = \Sigma_{ v \in V(D) } f(v) $. The Roman domination number of a digraph $D$, denoted by $ \gamma_R (D) $, is the minimum weight of an RDF on $D$. In this paper, for any integer $k$ with $ 2 \le k \le \gamma(D) $, we characterize the digraphs $D$ of order $ n \ge 4 $ with $ \delta − (D) \ge 1 $ for which $ \gamma_R(D) = (D) + k $ holds. We also characterize the digraphs $D$ of order $ n \ge k $ with $ \gamma_R(D) = k $ for any positive integer $k$. In addition, we present a Nordhaus-Gaddum bound on the Roman domination number of digraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 13-21
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Various Bounds for Liar’s Domination Number
Autorzy:
Alimadadi, Abdollah
Mojdeh, Doost Ali
Rad, Nader Jafari
Powiązania:
https://bibliotekanauki.pl/articles/31340859.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
liar’s domination
diameter
regular graph
Nordhaus-Gaddum
Opis:
Let $ G = (V,E) $ be a graph. A set $ S \subseteq V $ is a dominating set if \( \bigcup_{v \in S} N[v] = V \), where $ N[v] $ is the closed neighborhood of $ v $. Let $ L \subseteq V $ be a dominating set, and let $v$ be a designated vertex in $V$ (an intruder vertex). Each vertex in $ L \cap N[v] $ can report that $v$ is the location of the intruder, but (at most) one $ x \in L \cap N[v] $ can report any $ w \in N[x] $ as the intruder location or $ x $ can indicate that there is no intruder in $ N[x] $. A dominating set $L$ is called a liar’s dominating set if every $ v \in V (G) $ can be correctly identified as an intruder location under these restrictions. The minimum cardinality of a liar’s dominating set is called the liar’s domination number, and is denoted by $ \gamma_{LR} (G) $. In this paper, we present sharp bounds for the liar’s domination number in terms of the diameter, the girth and clique covering number of a graph. We present two Nordhaus-Gaddum type relations for $ \gamma_{LR} (G) $, and study liar’s dominating set sensitivity versus edge-connectivity. We also present various bounds for the liar’s domination component number, that is, the maximum number of components over all minimum liar’s dominating sets.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 629-641
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the hat problem on a graph
Autorzy:
Krzywkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/256048.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
hat problem
graph
degree
neighborhood
neighborhood-dominated
unicyclic
universal vertex
Nordhaus-Gaddum
Opis:
The topic of this paper is the hat problem in which each of n players is uniformly and independently fitted with a blue or red hat. Then everybody can try to guess simultaneously his own hat color by looking at the hat colors of the other players. The team wins if at least one player guesses his hat color correctly, and no one guesses his hat color wrong; otherwise the team loses. The aim is to maximize the probability of winning. In this version every player can see everybody excluding himself. We consider such a problem on a graph, where vertices correspond to players, and a player can see each player to whom he is connected by an edge. The solution of the hat problem on a graph is known for trees and for cycles on four or at least nine vertices. In this paper first we give an upper bound on the maximum chance of success for graphs with neighborhood-dominated vertices. Next we solve the problem on unicyclic graphs containing a cycle on at least nine vertices. We prove that the maximum chance of success is one by two. Then we consider the hat problem on a graph with a universal vertex. We prove that there always exists an optimal strategy such that in every case some vertex guesses its color. Moreover, we prove that there exists a graph with a universal vertex for which there exists an optimal strategy such that in some case no vertex guesses its color. We also give some Nordhaus-Gaddum type inequalities.
Źródło:
Opuscula Mathematica; 2012, 32, 2; 285-296
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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