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Wyszukujesz frazę "edge-connectivity" wg kryterium: Temat


Wyświetlanie 1-11 z 11
Tytuł:
Minimum Edge Cuts in Diameter 2 Graphs
Autorzy:
Bickle, Allan
Schwenk, Allen
Powiązania:
https://bibliotekanauki.pl/articles/31343375.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge connectivity
diameter
Opis:
Plesnik proved that the edge connectivity and minimum degree are equal for diameter 2 graphs. We provide a streamlined proof of this fact and characterize the diameter 2 graphs with a nontrivial minimum edge cut.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 605-608
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Graphs with Large Generalized (Edge-)Connectivity
Autorzy:
Li, Xueliang
Mao, Yaping
Powiązania:
https://bibliotekanauki.pl/articles/31340594.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
(edge-)connectivity
Steiner tree
internally disjoint trees
edge-disjoint trees
packing
generalized (edge-)connectivity
Opis:
The generalized $k$-connectivity $ \kappa_k (G) $ of a graph $G$, introduced by Hager in 1985, is a nice generalization of the classical connectivity. Recently, as a natural counterpart, we proposed the concept of generalized $k$-edge-connectivity $ \lambda_k (G)$. In this paper, graphs of order $n$ such that $ \kappa_k (G) = n - k/2 - 1 $ and $ \lambda_k (G) = n - k/2 - 1 $ for even $k$ are characterized.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 931-958
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Sharp Lower Bound For The Generalized 3-Edge-Connectivity Of Strong Product Graphs
Autorzy:
Sun, Yuefang
Powiązania:
https://bibliotekanauki.pl/articles/31341589.pdf
Data publikacji:
2017-11-27
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
generalized connectivity
generalized edge-connectivity
strong product
Opis:
The generalized $k$-connectivity $ \kappa_k (G) $ of a graph $G$, mentioned by Hager in 1985, is a natural generalization of the path-version of the classical connectivity. As a natural counterpart of this concept, Li et al. in 2011 introduced the concept of generalized $k$-edge-connectivity which is defined as $ \lambda_k (G) = \text{min} \{ \lambda_G (S) | S \subseteq V (G) $ and $ |S| = k \} $, where $ \lambda_G (S) $ denote the maximum number $ \mathcal{l} $ of pairwise edge-disjoint trees $ T_1 $, $ T_2 $, . . ., $ T_\mathcal{l} $ in $G$ such that $S \subseteq V (T_i)$ for $ 1 \le i \le \mathcal{l} $. In this paper we get a sharp lower bound for the generalized 3-edge-connectivity of the strong product of any two connected graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 4; 975-988
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cospectral Pairs of Regular Graphs with Different Connectivity
Autorzy:
Haemers, Willem H.
Powiązania:
https://bibliotekanauki.pl/articles/31552242.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph spectrum
vertex-connectivity
edge-connectivity
spectral characterization
Opis:
For vertex- and edge-connectivity we construct infinitely many pairs of regular graphs with the same spectrum, but with different connectivity.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 577-584
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
More on even [a,b]-factors in graphs
Autorzy:
Khodkar, Abdollah
Xu, Rui
Powiązania:
https://bibliotekanauki.pl/articles/743747.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
[a,b]-factor
spanning graph
edge-connectivity
Opis:
In this note we give a characterization of the complete bipartite graphs which have an even (odd) [a,b]-factor. For general graphs we prove that an a-edge connected graph G with n vertices and with δ(G) ≥ max{a+1,an/(a+b) + a - 2} has an even [a,b]-factor, where a and b are even and 2 ≤ a ≤ b. With regard to the edge-connectivity this result is slightly better than one of the similar results obtained by Kouider and Vestergaard in 2004 and unlike their results, this result has no restriction on the order of graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 1; 193-204
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Minimum Size of a Graph with Given Tree Connectivity
Autorzy:
Sun, Yuefang
Sheng, Bin
Jin, Zemin
Powiązania:
https://bibliotekanauki.pl/articles/32083875.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
generalized connectivity
tree connectivity
eneralized k-connectivity
generalized k-edge-connectivity
packing
Opis:
For a graph $G = (V, E)$ and a set $S ⊆ V$ of at least two vertices, an $S$-tree is a such subgraph $T$ of $G$ that is a tree with $S ⊆ V(T)$. Two $S$-trees $T_1$ and $T_2$ are said to be internally disjoint if $E(T_1) ∩ E(T_2) = ∅$ and $V(T_1) ∩ V(T_2) = S$, and edge-disjoint if $E(T_1) ∩ E(T_2) = ∅$. The generalized local connectivity $κ_G(S)$ (generalized local edge-connectivity $λ_G(S)$, respectively) is the maximum number of internally disjoint (edge-disjoint, respectively) $S$-trees in $G$. For an integer $k$ with $2 ≤ k ≤ n$, the generalized $k$-connectivity (generalized $k$-edge-connectivity, respectively) is defined as $κ_k(G) = min{κ_G(S) | S ⊆ V(G), |S| = k} (λ_k(G) = min{λ_G(S) | S ⊆ V(G), |S| = k}$, respectively). Let $f(n, k, t)$ ($g(n, k, t)$, respectively) be the minimum size of a connected graph $G$ with order $n$ and $κ_k(G) = t$ ($λ_k(G) = t$, respectively), where $3 ≤ k ≤ n$ and \(1≤t≤n-⌈\frac{k}{2}⌉\). For general $k$ and $t$, Li and Mao obtained a lower bound for $g(n, k, t)$ which is tight for the case $k = 3$. We show that the bound also holds for $f(n, k, t)$ and is tight for the case $k = 3$. When t is general, we obtain upper bounds of both $f(n, k, t)$ and $g(n, k, t)$ for $k ∈ {3, 4, 5}$, and all of these bounds can be attained. When $k$ is general, we get an upper bound of $g(n, k, t)$ for $t ∈ {1, 2, 3, 4}$ and an upper bound of $f(n, k, t)$ for $t ∈ {1, 2, 3}$. Moreover, both bounds can be attained.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 409-425
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sharp Upper Bounds for Generalized Edge-Connectivity of Product Graphs
Autorzy:
Sun, Yuefang
Powiązania:
https://bibliotekanauki.pl/articles/31340760.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
generalized edge-connectivity
Cartesian product
strong product
lexicographic product
Opis:
The generalized $k$-connectivity $ \kappa_k (G) $ of a graph $G$ was introduced by Hager in 1985. As a natural counterpart of this concept, Li et al. in 2011 introduced the concept of generalized $k$-edge-connectivity which is defined as $ \lambda k(G) = \text{min} \{ \lambda (S) : S \subseteq V (G) \text{ and } |S| = k \} $, where $ \lambda(S) $ denote the maximum number $ \mathcal{l} $ of pairwise edge-disjoint trees $ T_1, T_2, . . ., T_\mathcal{l} $ in $G$ such that $ S \subseteq V ( T_i ) $ for $ 1 \le i \le \mathcal{l} $. In this paper, we study the generalized edge- connectivity of product graphs and obtain sharp upper bounds for the generalized 3-edge-connectivity of Cartesian product graphs and strong product graphs. Among our results, some special cases are also discussed.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 833-843
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sufficient Conditions for Maximally Edge-Connected and Super-Edge-Connected Graphs Depending on The Clique Number
Autorzy:
Volkmann, Lutz
Powiązania:
https://bibliotekanauki.pl/articles/31343389.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-connectivity
clique number
maximally edge-connected graphs
super-edge-connected graphs
Opis:
Let G be a connected graph with minimum degree δ and edge-connectivity λ. A graph is maximally edge-connected if λ = δ, and it is super-edgeconnected if every minimum edge-cut is trivial; that is, if every minimum edge-cut consists of edges incident with a vertex of minimum degree. The clique number ω(G) of a graph G is the maximum cardinality of a complete subgraph of G. In this paper, we show that a connected graph G with clique number ω(G) ≤ r is maximally edge-connected or super-edge-connected if the number of edges is large enough. These are generalizations of corresponding results for triangle-free graphs by Volkmann and Hong in 2017.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 567-573
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Sufficient Condition for Graphs to Be Super k-Restricted Edge Connected
Autorzy:
Wang, Shiying
Wang, Meiyu
Zhang, Lei
Powiązania:
https://bibliotekanauki.pl/articles/31341790.pdf
Data publikacji:
2017-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
neighborhood
k -restricted edge connectivity
super k -restricted edge connected graph
Opis:
For a subset $S$ of edges in a connected graph $G$, $S$ is a $k$-restricted edge cut if $G − S$ is disconnected and every component of $G − S$ has at least $k$ vertices. The $k$-restricted edge connectivity of $G$, denoted by $ \lambda_k (G) $, is defined as the cardinality of a minimum $k$-restricted edge cut. Let \( \xi_k(G) = \text{min} \{ | [ X , \overline{X} ] | : |X| = k, G[X] \) is connected $ \} $, where $ \overline{X} = V (G) \backslash X $. A graph $G$ is super $k$-restricted edge connected if every minimum $k$-restricted edge cut of $G$ isolates a component of order exactly $k$. Let $k$ be a positive integer and let $G$ be a graph of order $ \nu \ge 2k$. In this paper, we show that if $ | N( u ) \cup N( v ) | \ge k +1 $ for all pairs $u$, $v$ of nonadjacent vertices and $ \xi_k (G) \le \floor{ ν/2}+k $, then $G$ is super $k$-restricted edge connected.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 3; 537-545
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
More on the Rainbow Disconnection in Graphs
Autorzy:
Bai, Xuqing
Chang, Renying
Huang, Zhong
Li, Xueliang
Powiązania:
https://bibliotekanauki.pl/articles/32222544.pdf
Data publikacji:
2022-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-coloring
edge-connectivity
rainbow disconnection coloring (number)
Erdős-Gallai type problem
Nordhaus-Gaddum type bounds
complexity
NP-hard (complete)
Opis:
Let G be a nontrivial edge-colored connected graph. An edge-cut R of G is called a rainbow-cut if no two of its edges are colored the same. An edge-colored graph G is rainbow disconnected if for every two vertices u and v of G, there exists a u-v-rainbow-cut separating them. For a connected graph G, the rainbow disconnection number of G, denoted by rd(G), is defined as the smallest number of colors that are needed in order to make G rainbow disconnected. In this paper, we first determine the maximum size of a connected graph G of order n with rd(G) = k for any given integers k and n with 1 ≤ k ≤ n − 1, which solves a conjecture posed only for n odd in [G. Chartrand, S. Devereaux, T.W. Haynes, S.T. Hedetniemi and P. Zhang, Rainbow disconnection in graphs, Discuss. Math. Graph Theory 38 (2018) 1007–1021]. From this result and a result in their paper, we obtain Erdős-Gallai type results for rd(G). Secondly, we discuss bounds on rd(G) for complete multipartite graphs, critical graphs with respect to the chromatic number, minimal graphs with respect to the chromatic index, and regular graphs, and we also give the values of rd(G) for several special graphs. Thirdly, we get Nordhaus-Gaddum type bounds for rd(G), and examples are given to show that the upper and lower bounds are sharp. Finally, we show that for a connected graph G, to compute rd(G) is NP-hard. In particular, we show that it is already NP-complete to decide if rd(G) = 3 for a connected cubic graph. Moreover, we show that for a given edge-colored (with an unbounded number of colors) connected graph G it is NP-complete to decide whether G is rainbow disconnected.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 4; 1185-1204
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Gutman Index and the Edge-Wiener Index of Graphs with Given Vertex-Connectivity
Autorzy:
Mazorodze, Jaya Percival
Mukwembi, Simon
Vetrík, Tomáš
Powiązania:
https://bibliotekanauki.pl/articles/31340463.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Gutman index
edge-Wiener index
vertex-connectivity
Opis:
The Gutman index and the edge-Wiener index have been extensively investigated particularly in the last decade. An important stream of re- search on graph indices is to bound indices in terms of the order and other parameters of given graph. In this paper we present asymptotically sharp upper bounds on the Gutman index and the edge-Wiener index for graphs of given order and vertex-connectivity κ, where κ is a constant. Our results substantially generalize and extend known results in the area.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 867-876
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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