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Wyszukujesz frazę "directed graph" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
On the Domination of Cartesian Product of Directed Cycles: Results for Certain Equivalence Classes of Lengths
Autorzy:
Mollard, Michel
Powiązania:
https://bibliotekanauki.pl/articles/30146581.pdf
Data publikacji:
2013-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
directed graph
Cartesian product
domination number
directed cycle
Opis:
Let \( \gamma ( \overrightarrow{C_m} \square \overrightarrow{C_n} ) \) be the domination number of the Cartesian product of directed cycles \( \overrightarrow{C_m} \) and \( \overrightarrow{C_n} \) for $m, n \ge 2 $. Shaheen [13] and Liu et al. ([11], [12]) determined the value of \( \gamma ( \overrightarrow{C_m} \square \overrightarrow{C_n} ) \) when $ m \le 6 $ and [12] when both $m$ and $ n \equiv 0 (\mod 3) $. In this article we give, in general, the value of \( \gamma ( \overrightarrow{C_m} \square \overrightarrow{C_n} ) \) when $ m \equiv 2(\mod 3) $ and improve the known lower bounds for most of the remaining cases. We also disprove the conjectured formula for the case $ m \equiv 0 ( \mod 3) $ appearing in [12].
Źródło:
Discussiones Mathematicae Graph Theory; 2013, 33, 2; 387-394
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Determinant of q-Distance Matrix of a Graph
Autorzy:
Li, Hong-Hai
Su, Li
Zhang, Jing
Powiązania:
https://bibliotekanauki.pl/articles/30147229.pdf
Data publikacji:
2014-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
q-distance matrix
determinant
weighted graph
directed graph
Opis:
In this note, we show how the determinant of the q-distance matrix Dq(T) of a weighted directed graph G can be expressed in terms of the corresponding determinants for the blocks of G, and thus generalize the results obtained by Graham et al. [R.L. Graham, A.J. Hoffman and H. Hosoya, On the distance matrix of a directed graph, J. Graph Theory 1 (1977) 85-88]. Further, by means of the result, we determine the determinant of the q-distance matrix of the graph obtained from a connected weighted graph G by adding the weighted branches to G, and so generalize in part the results obtained by Bapat et al. [R.B. Bapat, S. Kirkland and M. Neumann, On distance matrices and Laplacians, Linear Algebra Appl. 401 (2005) 193- 209]. In particular, as a consequence, determinantal formulae of q-distance matrices for unicyclic graphs and one class of bicyclic graphs are presented.
Źródło:
Discussiones Mathematicae Graph Theory; 2014, 34, 1; 103-111
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Undirected and directed graphs with near polynomial growth
Autorzy:
Trofimov, V.
Powiązania:
https://bibliotekanauki.pl/articles/743188.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
vertex-symmetric graph
vertex-symmetric directed graph
near polynomial growth
multivalued mapping
Opis:
The growth function of a graph with respect to a vertex is near polynomial if there exists a polynomial bounding it above for infinitely many positive integers. In the paper vertex-symmetric undirected graphs and vertex-symmetric directed graphs with coinciding in- and out-degrees are described in the case their growth functions are near polynomial.
Źródło:
Discussiones Mathematicae Graph Theory; 2003, 23, 2; 383-391
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Twin Minus Total Domination Numbers In Directed Graphs
Autorzy:
Dehgardi, Nasrin
Atapour, Maryam
Powiązania:
https://bibliotekanauki.pl/articles/31341587.pdf
Data publikacji:
2017-11-27
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
twin minus total dominating function
twin minus total domination number
directed graph
Opis:
Let $ D = (V,A) $ be a finite simple directed graph (shortly, digraph). A function $ f : V \rightarrow {−1, 0, 1} $ is called a twin minus total dominating function (TMTDF) if $ f(N^−(v)) \ge 1 $ and $ f(N^+(v)) \ge 1 $ for each vertex $ v \in V $. The twin minus total domination number of $D$ is $\gamma_{mt}^\ast (D) = \text{min} \{ w(f) | f $ is a TMTDF of $ D \} $. In this paper, we initiate the study of twin minus total domination numbers in digraphs and we present some lower bounds for $ \gamma_{mt}^\ast (D) $ in terms of the order, size and maximum and minimum in-degrees and out-degrees. In addition, we determine the twin minus total domination numbers of some classes of digraphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 4; 989-1004
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isomorphisms and traversability of directed path graphs
Autorzy:
Broersma, Hajo
Li, Xueliang
Powiązania:
https://bibliotekanauki.pl/articles/743350.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
directed path graph
line digraph
isomorphism
travers-ability
Opis:
The concept of a line digraph is generalized to that of a directed path graph. The directed path graph Pₖ(D) of a digraph D is obtained by representing the directed paths on k vertices of D by vertices. Two vertices are joined by an arc whenever the corresponding directed paths in D form a directed path on k+1 vertices or form a directed cycle on k vertices in D. In this introductory paper several properties of P₃(D) are studied, in particular with respect to isomorphism and traversability. In our main results, we characterize all digraphs D with P₃(D) ≅ D, we show that P₃(D₁) ≅ P₃(D₂) "almost always" implies D₁ ≅ D₂, and we characterize all digraphs with Eulerian or Hamiltonian P₃-graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2002, 22, 2; 215-228
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Factoring directed graphs with respect to the cardinal product in polynomial time
Autorzy:
Imrich, Wilfried
Klöckl, Werner
Powiązania:
https://bibliotekanauki.pl/articles/743472.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
directed graphs
cardinal product
graph algorithms
Opis:
By a result of McKenzie [4] finite directed graphs that satisfy certain connectivity and thinness conditions have the unique prime factorization property with respect to the cardinal product. We show that this property still holds under weaker connectivity and stronger thinness conditions. Furthermore, for such graphs the factorization can be determined in polynomial time.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 3; 593-601
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Factoring directed graphs with respect to the cardinal product in polynomial time II
Autorzy:
Imrich, Wilfried
Klöckl, Werner
Powiązania:
https://bibliotekanauki.pl/articles/744038.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
directed graphs
cardinal product
graph algorithms
Opis:
By a result of McKenzie [7] all finite directed graphs that satisfy certain connectivity conditions have unique prime factorizations with respect to the cardinal product. McKenzie does not provide an algorithm, and even up to now no polynomial algorithm that factors all graphs satisfying McKenzie's conditions is known. Only partial results [1,3,5] have been published, all of which depend on certain thinness conditions of the graphs to be factored.
In this paper we weaken the thinness conditions and thus significantly extend the class of graphs for which the prime factorization can be found in polynomial time.
Źródło:
Discussiones Mathematicae Graph Theory; 2010, 30, 3; 461-474
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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