Results 21 to 30 of about 834 (84)
The hull number of an oriented graph
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 36, Page 2265-2275, 2003., 2003 We present characterizations of connected graphs G of order n ≥ 2 for which h+(G) = n. It is shown that for every two integers n and m with 11≤n−≤m≤(n2), there exists a connected graph G of order n and size m such that for each integer k with 2 ≤ k ≤ n, there exists an orientation of G with hull number G.
Gary Chartrand +2 more
wiley +1 more source
Classification of Filiform Lie Algebras up to dimension 7 Over Finite Fields
Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica, 2016 This paper tries to develop a recent research which consists in using Discrete Mathematics as a tool in the study of the problem of the classification of Lie algebras in general, dealing in this case with filiform Lie algebras up to dimension 7 over ...
Falcón Óscar J. +4 more
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Discrete Mathematics & Theoretical Computer Science, 2023 Mixed graphs have both directed and undirected edges. A mixed cage is a regular mixed graph of given girth with minimum possible order. In this paper mixed cages are studied. Upper bounds are obtained by general construction methods and computer searches.
Geoffrey Exoo
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An algebraic framework of weighted directed graphs
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 58, Page 3657-3678, 2003., 2003 We show that an algebraic formulation of weighted directed graphs leads to introducing a k‐vector space equipped with two coproducts Δ and Δ˜ verifying the so‐called coassociativity breaking equation (Δ˜⊗id)Δ=(id⊗Δ)Δ˜. Such a space is called an L‐coalgebra.
Philippe Leroux
wiley +1 more source
The Dichromatic Number of Infinite Families of Circulant Tournaments
Discussiones Mathematicae Graph Theory, 2017 The dichromatic number dc(D) of a digraph D is defined to be the minimum number of colors such that the vertices of D can be colored in such a way that every chromatic class induces an acyclic subdigraph in D.
Javier Nahid, Llano Bernardo
doaj +1 more source
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
wiley +1 more source
Products Of Digraphs And Their Competition Graphs
Discussiones Mathematicae Graph Theory, 2016 If D = (V, A) is a digraph, its competition graph (with loops) CGl(D) has the vertex set V and {u, v} ⊆ V is an edge of CGl(D) if and only if there is a vertex w ∈ V such that (u, w), (v, w) ∈ A.
Sonntag Martin, Teichert Hanns-Martin
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The second out-neighborhood for local tournaments
Open Mathematics, 2020 Sullivan stated the conjectures: (1) every oriented graph has a vertex x such that d ++(x) ≥ d −(x) and (2) every oriented graph has a vertex x such that d ++(x) + d +(x) ≥ 2d −(x)
Li Ruijuan, Liang Juanjuan
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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
wiley +1 more source