Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "rainbow coloring" wg kryterium: Temat


Wyświetlanie 1-15 z 15
Tytuł:
Facial Rainbow Coloring of Plane Graphs
Autorzy:
Jendroľ, Stanislav
Kekeňáková, Lucia
Powiązania:
https://bibliotekanauki.pl/articles/31343192.pdf
Data publikacji:
2019-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
cyclic coloring
rainbow coloring
plane graphs
Opis:
A vertex coloring of a plane graph $G$ is a facial rainbow coloring if any two vertices of $G$ connected by a facial path have distinct colors. The facial rainbow number of a plane graph $G$, denoted by $ rb(G) $, is the minimum number of colors that are necessary in any facial rainbow coloring of $G$. Let $L(G)$ denote the order of a longest facial path in $G$. In the present note we prove that $ rb(T) \le \floor{ 3/2 L(T) } $ for any tree $T$ and $rb(G) \le \ceil{ 5/3 L(G) } $ for arbitrary simple graph $G$. The upper bound for trees is tight. For any simple 3-connected plane graph $G$ we have $ rb(G) \le L(G) + 5 $.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 4; 889-897
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rainbow Connection Number of Dense Graphs
Autorzy:
Li, Xueliang
Liu, Mengmeng
Schiermeyer, Ingo
Powiązania:
https://bibliotekanauki.pl/articles/30146190.pdf
Data publikacji:
2013-07-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-colored graph
rainbow coloring
rainbow connection number
Opis:
An edge-colored graph $G$ is rainbow connected, if any two vertices are connected by a path whose edges have distinct colors. The rainbow connection number of a connected graph $G$, denoted $rc(G)$, is the smallest number of colors that are needed in order to make $G$ rainbow connected. In this paper we show that $rc(G) \leq 3$ if \( |E(G)| \geq \binom{n-2}{2} + 2 \), and $ rc(G) \leq 4 $ if \( |E(G)| \geq \binom{n-3}{2} + 3 \). These bounds are sharp.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 3; 603-611
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vertex rainbow colorings of graphs
Autorzy:
Fujie-Okamoto, Futaba
Kolasinski, Kyle
Lin, Jianwei
Zhang, Ping
Powiązania:
https://bibliotekanauki.pl/articles/743667.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rainbow path
vertex rainbow coloring
vertex rainbow connection number
Opis:
In a properly vertex-colored graph G, a path P is a rainbow path if no two vertices of P have the same color, except possibly the two end-vertices of P. If every two vertices of G are connected by a rainbow path, then G is vertex rainbow-connected. A proper vertex coloring of a connected graph G that results in a vertex rainbow-connected graph is a vertex rainbow coloring of G. The minimum number of colors needed in a vertex rainbow coloring of G is the vertex rainbow connection number vrc(G) of G. Thus if G is a connected graph of order n ≥ 2, then 2 ≤ vrc(G) ≤ n. We present characterizations of all connected graphs G of order n for which vrc(G) ∈ {2,n-1,n} and study the relationship between vrc(G) and the chromatic number χ(G) of G. For a connected graph G of order n and size m, the number m-n+1 is the cycle rank of G. Vertex rainbow connection numbers are determined for all connected graphs of cycle rank 0 or 1 and these numbers are investigated for connected graphs of cycle rank 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 1; 63-80
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gallai-Ramsey Numbers for Rainbow $S_3^+$ and Monochromatic Paths
Autorzy:
Li, Xihe
Wang, Ligong
Powiązania:
https://bibliotekanauki.pl/articles/32387979.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Gallai-Ramsey number
rainbow coloring
monochromatic paths
Opis:
Motivated by Ramsey theory and other rainbow-coloring-related problems, we consider edge-colorings of complete graphs without rainbow copy of some fixed subgraphs. Given two graphs $G$ and $H$, the $k$-colored Gallai-Ramsey number $ gr_k(G : H)$ is defined to be the minimum positive integer $n$ such that every $k$-coloring of the complete graph on $n$ vertices contains either a rainbow copy of $G$ or a monochromatic copy of $H$. Let $ S_3^+$ be the graph on four vertices consisting of a triangle with a pendant edge. In this paper, we prove that $ gr_k(S_3^+ : P_5) = k+4 (k \ge 5)$, $ gr_k(S_3^+ : mP_2) = (m-1)k+m+1 (k \ge 1) $, $ gr_k(S_3^+ : P_3 \cup P_2) = k+4 (k \ge 5) $ and $ gr_k( S_3^+ : 2P_3) = k+5 (k \ge1) $.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 349-362
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The strong 3-rainbow index of some certain graphs and its amalgamation
Autorzy:
Awanis, Zata Yumni
Salman, A.N.M.
Powiązania:
https://bibliotekanauki.pl/articles/2216176.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
amalgamation
rainbow coloring
rainbow Steiner tree
strong k-rainbow index
Opis:
We introduce a strong k-rainbow index of graphs as modification of well-known k-rainbow index of graphs. A tree in an edge-colored connected graph G, where adjacent edge may be colored the same, is a rainbow tree if all of its edges have distinct colors. Let k be an integer with 2 ≤ k ≤ n. The strong k-rainbow index of G, denoted by $srx_k(G)$, is the minimum number of colors needed in an edge-coloring of G so that every k vertices of G is connected by a rainbow tree with minimum size. We focus on k = 3. We determine the strong 3-rainbow index of some certain graphs. We also provide a sharp upper bound for the strong 3-rainbow index of amalgamation of graphs. Additionally, we determine the exact values of the strong 3-rainbow index of amalgamation of some graphs.
Źródło:
Opuscula Mathematica; 2022, 42, 4; 527-547
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Almost-Rainbow Edge-Colorings of Some Small Subgraphs
Autorzy:
Krop, Elliot
Krop, Irina
Powiązania:
https://bibliotekanauki.pl/articles/30097998.pdf
Data publikacji:
2013-09-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Ramsey theory
generalized Ramsey theory
rainbow-coloring
edge-coloring
Erdös problem
Opis:
Let $ f(n, p, q) $ be the minimum number of colors necessary to color the edges of $ K_n $ so that every $ K_p $ is at least $ q $-colored. We improve current bounds on these nearly “anti-Ramsey” numbers, first studied by Erdös and Gyárfás. We show that $ f(n, 5, 0) \ge \frac{7}{4} n - 3 $, slightly improving the bound of Axenovich. We make small improvements on bounds of Erdös and Gyárfás by showing $ \frac{5}{6} n + 1 \leq f(n,4,5) $ and for all even $ n ≢ 1(\text{mod } 3) $, $ f(n, 4, 5) \leq n−1 $. For a complete bipartite graph $ G= K_{n,n}$, we show an $n$-color construction to color the edges of $ G $ so that every $ C_4 ⊆ G $ is colored by at least three colors. This improves the best known upper bound of Axenovich, Füredi, and Mubayi.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 4; 771-784
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rainbow Total-Coloring of Complementary Graphs and Erdős-Gallai Type Problem For The Rainbow Total-Connection Number
Autorzy:
Sun, Yuefang
Jin, Zemin
Tu, Jianhua
Powiązania:
https://bibliotekanauki.pl/articles/31342242.pdf
Data publikacji:
2018-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Rainbow total-coloring
rainbow total-connection number
complementary graph
Erdős-Gallai type problem
Opis:
A total-colored graph $G$ is rainbow total-connected if any two vertices of $G$ are connected by a path whose edges and internal vertices have distinct colors. The rainbow total-connection number, denoted by $ rtc(G) $, of a graph $G$ is the minimum number of colors needed to make $G$ rainbow total-connected. In this paper, we prove that $ rtc(G) $ can be bounded by a constant 7 if the following three cases are excluded: $ diam( \overline{G} ) = 2 $, $ diam( \overline{G} ) = 3 $, $ \overline{G} $ contains exactly two connected components and one of them is a trivial graph. An example is given to show that this bound is best possible. We also study Erdős-Gallai type problem for the rainbow total-connection number, and compute the lower bounds and precise values for the function $ f(n, k) $, where $ f(n, k) $ is the minimum value satisfying the following property: if $ |E(G)| \ge f(n, k) $, then $ rtc(G) \le k $.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 4; 1023-1036
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:
Rainbow Disconnection in Graphs
Autorzy:
Chartrand, Gary
Devereaux, Stephen
Haynes, Teresa W.
Hedetniemi, Stephen T.
Zhang, Ping
Powiązania:
https://bibliotekanauki.pl/articles/31342243.pdf
Data publikacji:
2018-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge coloring
rainbow connection
rainbow disconnection
Opis:
Let G be a nontrivial connected, edge-colored graph. An edge-cut R of G is called a rainbow cut if no two edges in R are colored the same. An edge-coloring of G is a rainbow disconnection coloring if for every two distinct vertices u and v of G, there exists a rainbow cut in G, where u and v belong to different components of G − R. We introduce and study the rainbow disconnection number rd(G) of G, which is defined as the minimum number of colors required of a rainbow disconnection coloring of G. It is shown that the rainbow disconnection number of a nontrivial connected graph G equals the maximum rainbow disconnection number among the blocks of G. It is also shown that for a nontrivial connected graph G of order n, rd(G) = n−1 if and only if G contains at least two vertices of degree n − 1. The rainbow disconnection numbers of all grids Pm □ Pn are determined. Furthermore, it is shown for integers k and n with 1 ≤ k ≤ n − 1 that the minimum size of a connected graph of order n having rainbow disconnection number k is n + k − 2. Other results and a conjecture are also presented.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 4; 1007-1021
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rainbow Connection Number of Graphs with Diameter 3
Autorzy:
Li, Hengzhe
Li, Xueliang
Sun, Yuefang
Powiązania:
https://bibliotekanauki.pl/articles/31342160.pdf
Data publikacji:
2017-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-coloring
rainbow path
rainbow connection number
diameter
Opis:
A path in an edge-colored graph G is rainbow if no two edges of the path are colored the same. The rainbow connection number rc(G) of G is the smallest integer k for which there exists a k-edge-coloring of G such that every pair of distinct vertices of G is connected by a rainbow path. Let f(d) denote the minimum number such that rc(G) ≤ f(d) for each bridgeless graph G with diameter d. In this paper, we shall show that 7 ≤ f(3) ≤ 9.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 1; 141-154
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Worm Colorings
Autorzy:
Goddard, Wayne
Wash, Kirsti
Xu, Honghai
Powiązania:
https://bibliotekanauki.pl/articles/31339329.pdf
Data publikacji:
2015-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
coloring
rainbow
monochromatic
forbidden
path
Opis:
Given a coloring of the vertices, we say subgraph H is monochromatic if every vertex of H is assigned the same color, and rainbow if no pair of vertices of H are assigned the same color. Given a graph G and a graph F, we define an F-WORM coloring of G as a coloring of the vertices of G without a rainbow or monochromatic subgraph H isomorphic to F. We present some results on this concept especially as regards to the existence, complexity, and optimization within certain graph classes. The focus is on the case that F is the path on three vertices.
Źródło:
Discussiones Mathematicae Graph Theory; 2015, 35, 3; 571-584
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vertex Colorings without Rainbow Subgraphs
Autorzy:
Goddard, Wayne
Xu, Honghai
Powiązania:
https://bibliotekanauki.pl/articles/31340560.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
coloring
rainbow
monochromatic
forbidden
path
Opis:
Given a coloring of the vertices of a graph G, we say a subgraph is rainbow if its vertices receive distinct colors. For a graph F, we define the F-upper chromatic number of G as the maximum number of colors that can be used to color the vertices of G such that there is no rainbow copy of F. We present some results on this parameter for certain graph classes. The focus is on the case that F is a star or triangle. For example, we show that the K3-upper chromatic number of any maximal outerplanar graph on n vertices is [n/2] + 1.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 989-1005
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
WORM Colorings of Planar Graphs
Autorzy:
Czap, J.
Jendrol’, S.
Valiska, J.
Powiązania:
https://bibliotekanauki.pl/articles/31341972.pdf
Data publikacji:
2017-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
plane graph
monochromatic path
rainbow path
WORM coloring
facial coloring
Opis:
Given three planar graphs $F$, $H$, and $G$, an $(F,H)$-WORM coloring of $G$ is a vertex coloring such that no subgraph isomorphic to $F$ is rainbow and no subgraph isomorphic to $H$ is monochromatic. If $G$ has at least one $(F,H)$-WORM coloring, then $ W_{F,H}^- (G)$ denotes the minimum number of colors in an $(F,H)$-WORM coloring of $G$. We show that (a) $W_{F,H}^- (G) \le 2 $ if $ |V (F)| \ge 3$ and $H$ contains a cycle, (b) $W_{F,H}^- (G) \le 3 $ if $ |V (F)| \ge 4$ and $H$ is a forest with $ \Delta (H) \ge 3$, (c) $W_{F,H}^- (G) \le 4 $ if $ |V (F)| \ge 5$ and $H$ is a forest with $1 \le \Delta (H) \le 2 $. The cases when both $F$ and $H$ are nontrivial paths are more complicated; therefore we consider a relaxation of the original problem. Among others, we prove that any 3-connected plane graph (respectively outerplane graph) admits a 2-coloring such that no facial path on five (respectively four) vertices is monochromatic.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 2; 353-368
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Vertex-Rainbow Index of A Graph
Autorzy:
Mao, Yaping
Powiązania:
https://bibliotekanauki.pl/articles/31340818.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
vertex-coloring
connectivity
vertex-rainbow S-tree
vertex- rainbow index
Nordhaus-Gaddum type
Opis:
The k-rainbow index rxk(G) of a connected graph G was introduced by Chartrand, Okamoto and Zhang in 2010. As a natural counterpart of the k-rainbow index, we introduce the concept of k-vertex-rainbow index rvxk(G) in this paper. In this paper, sharp upper and lower bounds of rvxk(G) are given for a connected graph G of order n, that is, 0 ≤ rvxk(G) ≤ n − 2. We obtain Nordhaus-Gaddum results for 3-vertex-rainbow index of a graph G of order n, and show that rvx3(G) + rvx3(Ḡ) = 4 for n = 4 and 2 ≤ rvx3(G) + rvx3(Ḡ) ≤ n − 1 for n ≥ 5. Let t(n, k, ℓ) denote the minimal size of a connected graph G of order n with rvxk(G) ≤ ℓ, where 2 ≤ ℓ ≤ n − 2 and 2 ≤ k ≤ n. Upper and lower bounds on t(n, k, ℓ) are also obtained.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 669-681
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Rainbow Vertex-Connection
Autorzy:
Li, Xueliang
Shi, Yongtang
Powiązania:
https://bibliotekanauki.pl/articles/30146636.pdf
Data publikacji:
2013-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rainbow vertex-connection
vertex coloring
minimum degree
2-step dominating set
Opis:
A vertex-colored graph is rainbow vertex-connected if any two vertices are connected by a path whose internal vertices have distinct colors. The rainbow vertex-connection of a connected graph $G$, denoted by $rvc(G)$, is the smallest number of colors that are needed in order to make $G$ rainbow vertex-connected. It was proved that if $G$ is a graph of order $n$ with minimum degree $ \delta $, then $ rvc(G) < 11n//\delta$. In this paper, we show that $rvc(G) \le 3n//(δ+1)+5$ for $ \delta \ge \sqrt{n-1} -1 $ and $ n \le 290 $, while $ rvc(G) \le 4n//(δ + 1) + 5 $ for $ 16 \le \delta \le \sqrt{n-1}-2 $ and $ rvc(G) \le 4n//(\delta + 1) + C(\delta) $ for $6 \le \delta \le 15$, where $ C(\delta) = e^\frac{ 3 \log (\delta^3 + 2 \delta^2 +3)-3(\log 3 - 1)}{\delta - 3} - 2$. We also prove that $ rvc(G) \le 3n//4 − 2 $ for $ \delta = 3$, $ rvc(G) \le 3n//5 − 8//5$ for $\delta = 4$ and $rvc(G) \le n//2 − 2$ for $\delta = 5$. Moreover, an example constructed by Caro et al. shows that when $ \delta \ge \sqrt{n-1} - 1 $ and $ \delta = 3, 4, 5 $, our bounds are seen to be tight up to additive constants.
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 2; 307-313
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-15 z 15

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies