Results 61 to 70 of about 197 (101)
, 1991 International Journal of Mathematics and Mathematical Sciences, Volume 16, Issue 3, Page 579-586, 1993.
Garry Johns, Karen Sleno
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Signed Total Roman Domination in Digraphs
Discussiones Mathematicae Graph Theory, 2017 Let D be a finite and simple digraph with vertex set V (D). A signed total Roman dominating function (STRDF) on a digraph D is a function f : V (D) → {−1, 1, 2} satisfying the conditions that (i) ∑x∈N−(v)f(x) ≥ 1 for each v ∈ V (D), where N−(v) consists ...
Volkmann Lutz
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Solving the kernel perfect problem by (simple) forbidden subdigraphs for digraphs in some families of generalized tournaments and generalized bipartite tournaments [PDF]
Discrete Mathematics & Theoretical Computer Science, 2018 A digraph such that every proper induced subdigraph has a kernel is said to be \emph{kernel perfect} (KP for short) (\emph{critical kernel imperfect} (CKI for short) resp.) if the digraph has a kernel (does not have a kernel resp.).
H. Galeana-Sánchez, M. Olsen
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Discussiones Mathematicae Graph Theory, 2018 A digraph is called irregular if its distinct vertices have distinct degree pairs. An irregular digraph is called minimal (maximal) if the removal of any arc (addition of any new arc) results in a non-irregular digraph. It is easily seen that the minimum
Górska Joanna +4 more
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Niche Hypergraphs of Products of Digraphs
Discussiones Mathematicae Graph Theory, 2020 If D = (V, A) is a digraph, its niche hypergraph Nℋ(D) = (V, ℰ) has the edge set ℰ={e⊆V||e|≥2∧∃ υ∈V:e=ND−(υ)∨e=ND+(υ)}{\cal E} = \{ {e \subseteq V| | e | \ge 2 \wedge \exists \, \upsilon \in V:e = N_D^ - ( \upsilon ) \vee e = N_D^ + ( \upsilon ...
Sonntag Martin, Teichert Hanns-Martin
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Bounds on the Signed Roman k-Domination Number of a Digraph
Discussiones Mathematicae Graph Theory, 2019 Let k be a positive integer. A signed Roman k-dominating function (SRkDF) on a digraph D is a function f : V (D) → {−1, 1, 2} satisfying the conditions that (i) Σx∈N−[v]f(x) ≥ k for each v ∈ V (D), where N−[v] is the closed in-neighborhood of v, and (ii)
Chen Xiaodan +2 more
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Some Results on 4-Transitive Digraphs
Discussiones Mathematicae Graph Theory, 2017 Let D be a digraph with set of vertices V and set of arcs A. We say that D is k-transitive if for every pair of vertices u, v ∈ V, the existence of a uv-path of length k in D implies that (u, v) ∈ A.
García-Vázquez Patricio Ricardo +1 more
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Super Edge-Connectivity and Zeroth-Order Randić Index
Discussiones Mathematicae Graph Theory, 2020 Define the zeroth-order Randić index as R0(G)=∑x∈V(G)1dG(x),{R^0}\left( G \right) = \sum\nolimits_{x \in V\left( G \right)} {{1 \over {\sqrt {{d_G}} \left( x \right)}},} where dG(x) denotes the degree of the vertex x.
He Zhihong, Lu Mei
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On characterization of finite modules by hypergraphs
Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica, 2022 With a finite R-module M we associate a hypergraph 𝒞𝒥ℋR(M) having the set V of vertices being the set of all nontrivial submodules of M. Moreover, a subset Ei of V with at least two elements is a hyperedge if for K, L in Ei there is K ∩ L ≠ = 0 and Ei is
Hamzekolaee Ali Reza Moniri +1 more
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𝕮-inverse of graphs and mixed graphs
Open MathematicsThis article introduces a generalization of the concept of inverse graphs applicable to both graphs and mixed graphs. Given a graph GG with adjacency matrix A(G)A\left(G), the inverse graph G−1{G}^{-1} is defined such that its adjacency matrix is similar
Alomari Omar +2 more
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