Results 31 to 40 of about 861 (108)
On incidence algebras and directed graphs
International Journal of Mathematics and Mathematical Sciences, Volume 31, Issue 5, Page 301-305, 2002., 2002 The incidence algebra I(X, ℝ) of a locally finite poset (X, ≤) has been defined and studied by Spiegel and O′Donnell (1997). A poset (V, ≤) has a directed graph (Gv, ≤) representing it. Conversely, any directed graph G without any cycle, multiple edges, and loops is represented by a partially ordered set VG.
Ancykutty Joseph
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About (k, l)-Kernels, Semikernels and Grundy Functions in Partial Line Digraphs
Discussiones Mathematicae Graph Theory, 2019 Let D be a digraph of minimum in-degree at least 1. We prove that for any two natural numbers k, l such that 1 ≤ l ≤ k, the number of (k, l)-kernels of D is less than or equal to the number of (k, l)-kernels of any partial line digraph ℒD. Moreover, if l
Balbuena C. +2 more
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Homomorphically Full Oriented Graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2023 Homomorphically full graphs are those for which every homomorphic image is isomorphic to a subgraph. We extend the definition of homomorphically full to oriented graphs in two different ways.
Thomas Bellitto +2 more
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Families of (1, 2)‐symplectic metrics on full flag manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 29, Issue 11, Page 651-664, 2002., 2002 We obtain new families of (1, 2)‐symplectic invariant metrics on the full complex flag manifolds F(n). For n ≥ 5, we characterize n − 3 different n‐dimensional families of (1, 2)‐symplectic invariant metrics on F(n). Each of these families corresponds to a different class of nonintegrable invariant almost complex structures on F(n).
Marlio Paredes
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Incidence matrices and line graphs of mixed graphs
Special Matrices, 2023 In the theory of line graphs of undirected graphs, there exists an important theorem linking the incidence matrix of the root graph to the adjacency matrix of its line graph. For directed or mixed graphs, however, there exists no analogous result.
Abudayah Mohammad +2 more
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Algorithmic aspects of bipartite graphs
International Journal of Mathematics and Mathematical Sciences, Volume 18, Issue 2, Page 299-304, 1995., 1995 We generalize previous work done by Donald J. Rose and Robert E. Tarjan [2], who developed efficient algorithms for use on directed graphs. This paper considers an edge elimination process on bipartite graphs, presenting several theorems which lead to an algorithm for computing the minimal fill‐in of a given ordered graph.
Mihály Bakonyi, Erik M. Varness
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Total Roman domination on the digraphs
Open Mathematics, 2023 Let D=(V,A)D=\left(V,A) be a simple digraph with vertex set VV, arc set AA, and no isolated vertex. A total Roman dominating function (TRDF) of DD is a function h:V→{0,1,2}h:V\to \left\{0,1,2\right\}, which satisfies that each vertex x∈Vx\in V with h(x ...
Zhang Xinhong, Song Xin, Li Ruijuan
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Existence and uniqueness of solutions to the norm minimum problem on digraphs
Open Mathematics, 2022 In this article, based on the path homology theory of digraphs, which has been initiated and studied by Grigor’yan, Lin, Muranov, and Yau, we prove the existence and uniqueness of solutions to the problem ∥w∥=minu∈Ω2(G),u≠012∥∂u−w∥22+∣u∣1\parallel w ...
Wang Chong
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Unordered Love in infinite directed graphs
International Journal of Mathematics and Mathematical Sciences, Volume 15, Issue 4, Page 753-756, 1992., 1992 A digraph D = (V, A) has the Unordered Love Property (ULP) if any two different vertices have a unique common outneighbor. If both (V, A) and (V, A−1) have the ULP, we say that D has the SDULP. A love‐master in D is a vertex ν0 connected both ways to every other vertex, such that D − ν0 is a disjoint union of directed cycles.
Peter D. Johnson Jr.
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Arc-Disjoint Hamiltonian Cycles in Round Decomposable Locally Semicomplete Digraphs
Discussiones Mathematicae Graph Theory, 2018 Let D = (V,A) be a digraph; if there is at least one arc between every pair of distinct vertices of D, then D is a semicomplete digraph. A digraph D is locally semicomplete if for every vertex x, the out-neighbours of x induce a semicomplete digraph and ...
Li Ruijuan, Han Tingting
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