Results 121 to 130 of about 8,914 (221)
Interval Digraphs and Bounded Bitolerance Digraphs
, 2001 Interval digraphs and bounded bitolerance digraphs are two different directed graph analogues to the well-known interval graphs. Both are contained in the class of digraphs of Ferrers Dimension at most two.
Trenk, Ann N., Shull, Randy
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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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Random Directed Graph Distributions in the Triad Census in Social Networks [PDF]
This paper uses the concept of the triad census first introduced by Holland and Leinhardt, and describes several distributions on directed graphs. Methods are presented for calculating the mean and the covariance matrix of the triad census for the ...
Stanley S. Wasserman
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Algebra universalisAbstract Call a finite relational structure k-Słupecki if its only surjective k -ary polymorphisms are essentially unary, and Słupecki if it is k -Słupecki
Kunos, Ádám +2 more
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Discrete Mathematics, 2012 We generalize the class of split graphs to the directed case and show that these split digraphs can be identified from their degree sequences. The first degree sequence characterization is an extension of the concept of splittance to directed graphs, while the second characterization says a digraph is split if and only if its degree sequence satisfies ...
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Journal of Combinatorial Mathematics and Combinatorial ComputingA ( 0 , 1 ) -labeling of a set is said to be friendly if the number of elements of the set labeled 0 and the number labeled 1 differ by at most 1. Let g be a labeling of the edge set of a graph that is induced by a labeling f of the vertex set. If both g and f are friendly then g is said to be a cordial labeling of the graph.
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Discrete Mathematics, 2000 Let \(G\) denote a strongly-connected digraph with \(n\) nodes, girth \(g\), and diameter \(D\). The author shows that if \(G\) has \(t\) nodes of out-degree one, then \(D\leq n-g+ t\). He also shows that if \(r\) denotes the minimum out-degree of \(G\), then \(g\leq \max\{\lceil n/r\rceil, 2r- 2\}\). This last result implies that when \(n\geq 2r^2- 3r+
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Discrete Mathematics, 2001 The author studies the problem of upward embedding on the round sphere and gives a characterization of all spherical digraphs.
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On cyclic Kautz digraphs [PDF]
, 2015 A prominent problem in Graph Theory is to find extremal graphs or digraphs with restrictions in their diameter, degree and number of vertices. Here we obtain a new family of digraphs with minimal diameter, that is, given the number of vertices and out ...
Böhmová, Katerina +2 more
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