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Wyszukujesz frazę "product of graphs" wg kryterium: Temat


Tytuł:
Nearly perfect sets in products of graphs
Autorzy:
Kwaśnik, M.
Perl, M.
Powiązania:
https://bibliotekanauki.pl/articles/2050769.pdf
Data publikacji:
2004
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
dominating sets
product of graphs
Opis:
The study of nearly perfect sets in graphs was initiated in [2]. Let $S \subseteq V(G)$. We say that $S$ is a nearly perfect set (or is nearly perfect) in $G$ if every vertex in $V(G) - S$ is adjacent to at most one vertex in $S$. A nearly perfect set $S$ in $G$ is called maximal if for every vertex $u \in V(G) - S, S \cup \{u\}$ is not nearly perfect in $G$. The minimum cardinality of a maximal nearly perfect set is denoted by $n_{p}(G)$. It is our purpose in this paper to determine maximal nearly perfect sets in two well-known products of two graphs, i.e. in the Cartesian product and in the strong product. Lastly, we give upper bounds of $n_{p}(G1 \times G2)$ and $n_{p}(G1 \otimes G2)$, for some special graphs $G1,G2$.
Źródło:
Opuscula Mathematica; 2004, 24, 2; 177-180
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nearly perfect sets in the n-fold products of graphs
Autorzy:
Perl, M.
Powiązania:
https://bibliotekanauki.pl/articles/255571.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
dominating sets
product of graphs
Opis:
The study of nearly perfect sets in graphs was initiated in [2], Let S ⊆ V(G). We say that S is a nearly perfect set (or is nearly perfect) in G if every vertex in V(G) - S is adjacent to at most one vertex in S. A nearly perfect set S in G is called 1-maximal if for every vertex u ∈ V(G) - S, S ∪ {u} is not nearly perfect in G. We denote the minimum cardinality of a 1-maximal nearly perfect set in G by np(G). We will call the 1-maximal nearly perfect set of the cardinality np(G) an np(G) - set. In this paper, we evaluate the parameter np(G) for some n-fold products of graphs. To this effect, we determine 1-maximal nearly perfect sets in the n-fold Cartesian product of graphs and in the n-fold strong product of graphs.
Źródło:
Opuscula Mathematica; 2007, 27, 1; 83-88
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Edge-Transitive Lexicographic and Cartesian Products
Autorzy:
Imrich, Wilfried
Iranmanesh, Ali
Klavžar, Sandi
Soltani, Abolghasem
Powiązania:
https://bibliotekanauki.pl/articles/31340755.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
edge-transitive graph
vertex-transitive graph
lexicographic product of graphs
Cartesian product of graphs
Opis:
In this note connected, edge-transitive lexicographic and Cartesian products are characterized. For the lexicographic product G ◦ H of a connected graph G that is not complete by a graph H, we show that it is edge-transitive if and only if G is edge-transitive and H is edgeless. If the first factor of G ∘ H is non-trivial and complete, then G ∘ H is edge-transitive if and only if H is the lexicographic product of a complete graph by an edgeless graph. This fixes an error of Li, Wang, Xu, and Zhao [11]. For the Cartesian product it is shown that every connected Cartesian product of at least two non-trivial factors is edge-transitive if and only if it is the Cartesian power of a connected, edge- and vertex-transitive graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 857-865
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Path-Pairability in the Cartesian Product of Graphs
Autorzy:
Mészáros, Gábor
Powiązania:
https://bibliotekanauki.pl/articles/31340793.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
path-pairable graphs
Cartesian product of graphs
Opis:
We study the inheritance of path-pairability in the Cartesian product of graphs and prove additive and multiplicative inheritance patterns of path-pairability, depending on the number of vertices in the Cartesian product. We present path-pairable graph families that improve the known upper bound on the minimal maximum degree of a path-pairable graph. Further results and open questions about path-pairability are also presented.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 743-758
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Proper Connection Of Direct Products
Autorzy:
Hammack, Richard H.
Taylor, Dewey T.
Powiązania:
https://bibliotekanauki.pl/articles/31341584.pdf
Data publikacji:
2017-11-27
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
direct product of graphs
proper connection of graphs
Opis:
The proper connection number of a graph is the least integer k for which the graph has an edge coloring with k colors, with the property that any two vertices are joined by a properly colored path. We prove that given two connected non-bipartite graphs, one of which is (vertex) 2-connected, the proper connection number of their direct product is 2.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 4; 1005-1013
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Note on the split domination number of the Cartesian product of paths
Autorzy:
Zwierzchowski, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/744304.pdf
Data publikacji:
2005
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination number
split domination number
Cartesian product of graphs
Opis:
In this note the split domination number of the Cartesian product of two paths is considered. Our results are related to [2] where the domination number of Pₘ ☐ Pₙ was studied. The split domination number of P₂ ☐ Pₙ is calculated, and we give good estimates for the split domination number of Pₘ ☐ Pₙ expressed in terms of its domination number.
Źródło:
Discussiones Mathematicae Graph Theory; 2005, 25, 1-2; 79-84
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Motion planning in Cartesian product graphs
Autorzy:
Deb, Biswajit
Kapoor, Kalpesh
Powiązania:
https://bibliotekanauki.pl/articles/30148104.pdf
Data publikacji:
2014-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
robot motion in a graph
Cartesian product of graphs
Opis:
Let $G$ be an undirected graph with $n$ vertices. Assume that a robot is placed on a vertex and $n − 2$ obstacles are placed on the other vertices. A vertex on which neither a robot nor an obstacle is placed is said to have a hole. Consider a single player game in which a robot or obstacle can be moved to adjacent vertex if it has a hole. The objective is to take the robot to a fixed destination vertex using minimum number of moves. In general, it is not necessary that the robot will take a shortest path between the source and destination vertices in graph $G$. In this article we show that the path traced by the robot coincides with a shortest path in case of Cartesian product graphs. We give the minimum number of moves required for the motion planning problem in Cartesian product of two graphs having girth 6 or more. A result that we prove in the context of Cartesian product of $P_n$ with itself has been used earlier to develop an approximation algorithm for ($n^2 − 1$)-puzzle
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 2; 207-221
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Well-Covered Direct Products
Autorzy:
Kuenzel, Kirsti
Rall, Douglas F.
Powiązania:
https://bibliotekanauki.pl/articles/32315158.pdf
Data publikacji:
2022-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
well-covered graph
direct product of graphs
isolatable vertex
Opis:
A graph G is well-covered if all maximal independent sets of G have the same cardinality. In 1992 Topp and Volkmann investigated the structure of well-covered graphs that have nontrivial factorizations with respect to some of the standard graph products. In particular, they showed that both factors of a well-covered direct product are also well-covered and proved that the direct product of two complete graphs (respectively, two cycles) is well-covered precisely when they have the same order (respectively, both have order 3 or 4). Furthermore, they proved that the direct product of two well-covered graphs with independence number one-half their order is well-covered. We initiate a characterization of nontrivial connected well-covered graphs G and H, whose independence numbers are strictly less than one-half their orders, such that their direct product G × H is well-covered. In particular, we show that in this case both G and H have girth 3 and we present several infinite families of such well-covered direct products. Moreover, we show that if G is a factor of any well-covered direct product, then G is a complete graph unless it is possible to create an isolated vertex by removing the closed neighborhood of some independent set of vertices in G.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 2; 627-640
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Constant Sum Partition of Sets of Integers and Distance Magic Graphs
Autorzy:
Cichacz, Sylwia
Gőrlich, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/31342439.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
constant sum partition
distance magic labeling
product of graphs
Opis:
Let $ A = {1, 2, . . ., tm+tn} $. We shall say that $A$ has the $(m, n, t)$-balanced constant-sum-partition property ($(m, n, t)$-BCSP-property) if there exists a partition of $A$ into $2t$ pairwise disjoint subsets $ A^1, A^2, ... , A^t, B^1, B^2, ... , B^t$ such that $ | A^i | = m $ and $ | B^i | = n $, and $ \Sigma_{ a \in A^i } \ a = \Sigma_ {b \in B^j} \ b $ for $ 1 \le i \le t $ and $ 1 \le j \le t $. In this paper we give sufficient and necessary conditions for a set $A$ to have the $(m, n, t)$-BCSP-property in the case when $m$ and $n$ are both even. We use this result to show some families of distance magic graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 97-106
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The General Position Problem on Kneser Graphs and on Some Graph Operations
Autorzy:
Ghorbani, Modjtaba
Maimani, Hamid Reza
Momeni, Mostafa
Mahid, Farhad Rahimi
Klavžar, Sandi
Rus, Gregor
Powiązania:
https://bibliotekanauki.pl/articles/32222714.pdf
Data publikacji:
2021-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
general position set
Kneser graphs
Cartesian product of graphs
corona over graphs
line graphs
Opis:
A vertex subset S of a graph G is a general position set of G if no vertex of S lies on a geodesic between two other vertices of S. The cardinality of a largest general position set of G is the general position number (gp-number) gp(G) of G. The gp-number is determined for some families of Kneser graphs, in particular for K(n, 2), n ≥ 4, and K(n, 3), n ≥ 9. A sharp lower bound on the gp-number is proved for Cartesian products of graphs. The gp-number is also determined for joins of graphs, coronas over graphs, and line graphs of complete graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 4; 1199-1213
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on the Thue Chromatic Number of Lexicographic Products of Graphs
Autorzy:
Peterin, Iztok
Schreyer, Jens
Škrabul’áková, Erika Fecková
Taranenko, Andrej
Powiązania:
https://bibliotekanauki.pl/articles/31342285.pdf
Data publikacji:
2018-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
non-repetitive colouring
Thue chromatic number
lexicographic product of graphs
Opis:
A sequence is called non-repetitive if none of its subsequences forms a repetition (a sequence r1r2⋯r2n such that ri = rn+i for all 1 ≤ i ≤ n). Let G be a graph whose vertices are coloured. A colouring ϕ of the graph G is non-repetitive if the sequence of colours on every path in G is non-repetitive. The Thue chromatic number, denoted by π(G), is the minimum number of colours of a non-repetitive colouring of G. In this short note we present two general upper bounds for the Thue chromatic number for the lexicographic product G ◦ H of graphs G and H with respect to some properties of the factors. One upper bound is then used to derive the exact values for π(G ◦ H) when G is a complete multipartite graph and H an arbitrary graph.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 3; 635-643
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the total restrained domination number of direct products of graphs
Autorzy:
Shiu, Wai
Chen, Hong-Yu
Chen, Xue-Gang
Sun, Pak
Powiązania:
https://bibliotekanauki.pl/articles/743278.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
total domination number
total restrained domination number
direct product of graphs
Opis:
Let G = (V,E) be a graph. A total restrained dominating set is a set S ⊆ V where every vertex in V∖S is adjacent to a vertex in S as well as to another vertex in V∖S, and every vertex in S is adjacent to another vertex in S. The total restrained domination number of G, denoted by $γ_r^t(G)$, is the smallest cardinality of a total restrained dominating set of G. We determine lower and upper bounds on the total restrained domination number of the direct product of two graphs. Also, we show that these bounds are sharp by presenting some infinite families of graphs that attain these bounds.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 4; 629-641
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Graphs with Clusters Perturbed by Regular Graphs—Aα-Spectrum and Applications
Autorzy:
Cardoso, Domingos M.
Pastén, Germain
Rojo, Oscar
Powiązania:
https://bibliotekanauki.pl/articles/31546556.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
cluster
convex combination of matrices
corona product of graphs
Aα-spectrum
Opis:
Given a graph G, its adjacency matrix A(G) and its diagonal matrix of vertex degrees D(G), consider the matrix Aα(G) = αD(G) + (1 − α)A(G), where α ∈ [0, 1). The Aα -spectrum of G is the multiset of eigenvalues of Aα(G) and these eigenvalues are the α-eigenvalues of G. A cluster in G is a pair of vertex subsets (C, S), where C is a set of cardinality |C| ≥ 2 of pairwise co-neighbor vertices sharing the same set S of |S| neighbors. Assuming that G is connected and it has a cluster (C, S), G(H) is obtained from G and an r-regular graph H of order |C| by identifying its vertices with the vertices in C, eigenvalues of Aα(G) and Aα(G(H)) are deduced and if Aα(H) is positive semidefinite, then the i-th eigenvalue of Aα(G(H)) is greater than or equal to i-th eigenvalue of Aα(G). These results are extended to graphs with several pairwise disjoint clusters (C1, S1), . . ., (Ck, Sk). As an application, the effect on the energy, α-Estrada index and α-index of a graph G with clusters when the edges of regular graphs are added to G are analyzed. Finally, the Aα-spectrum of the corona product G ◦ H of a connected graph G and a regular graph H is determined.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 451-466
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the rainbow connection of Cartesian products and their subgraphs
Autorzy:
Klavžar, Sandi
Mekiš, Gašper
Powiązania:
https://bibliotekanauki.pl/articles/743307.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
rainbow connection
strong rainbow connection
Cartesian product of graphs
isometric subgraph
hypercube
Opis:
Rainbow connection number of Cartesian products and their subgraphs are considered. Previously known bounds are compared and non-existence of such bounds for subgraphs of products are discussed. It is shown that the rainbow connection number of an isometric subgraph of a hypercube is bounded above by the rainbow connection number of the hypercube. Isometric subgraphs of hypercubes with the rainbow connection number as small as possible compared to the rainbow connection of the hypercube are constructed. The concept of c-strong rainbow connected coloring is introduced. In particular, it is proved that the so-called Θ-coloring of an isometric subgraph of a hypercube is its unique optimal c-strong rainbow connected coloring.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 4; 783-793
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On θ-graphs of partial cubes
Autorzy:
Klavžar, Sandi
Kovse, Matjaz
Powiązania:
https://bibliotekanauki.pl/articles/743784.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
intersection graph
partial cube
median graph
expansion theorem
Cartesian product of graphs
Opis:
The Θ-graph Θ(G) of a partial cube G is the intersection graph of the equivalence classes of the Djoković-Winkler relation. Θ-graphs that are 2-connected, trees, or complete graphs are characterized. In particular, Θ(G) is complete if and only if G can be obtained from K₁ by a sequence of (newly introduced) dense expansions. Θ-graphs are also compared with familiar concepts of crossing graphs and τ-graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 2; 313-321
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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