Results 31 to 40 of about 28,427 (196)
ITM Web of Conferences, 2018 The quasi-pseudo metrics on the vertices of a digraph induces a unique bitopology. In this work, we obtained that a bitopology is associated with any knot km, where k is crossing points of knot and m = 1,2 by using quasi-pseudo metrics on the vertices of
Elmali Ceren Sultan +2 more
doaj +1 more source
On the digraph of a unitary matrix
, 2003 Given a matrix M of size n, a digraph D on n vertices is said to be the digraph of M, when M_{ij} is different from 0 if and only if (v_{i},v_{j}) is an arc of D.
Grössing Gerhard +5 more
core +2 more sources
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
doaj +1 more source
The Existence of Planar Hypotraceable Oriented Graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 A digraph is \emph{traceable} if it has a path that visits every vertex. A digraph $D$ is \emph{hypotraceable} if $D$ is not traceable but $D-v$ is traceable for every vertex $v\in V(D)$.
Susan van Aardt +2 more
doaj +1 more source
On the existence and number of $(k+1)$-kings in $k$-quasi-transitive digraphs
, 2012 Let $D=(V(D), A(D))$ be a digraph and $k \ge 2$ an integer. We say that $D$ is $k$-quasi-transitive if for every directed path $(v_0, v_1,..., v_k)$ in $D$, then $(v_0, v_k) \in A(D)$ or $(v_k, v_0) \in A(D)$.
Galeana-Sánchez, Hortensia +2 more
core +1 more source
Journal of Combinatorial Theory, Series B, 1981 AbstractLet G be a directed graph on n vertices (single loops allowed) such that there are λ directed paths of length k from P to Q for any distinct pair of vertices (P, Q). We prove that if n > 2 and k > 2, G is regular. The regular case is also discussed.
Bridges, W.G, Mena, R.A
openaire +2 more sources
H-kernels by walks in H-colored digraphs and the color-class digraph
AKCE International Journal of Graphs and Combinatorics, 2016 Let H be a digraph possibly with loops and D a finite digraph without loops whose arcs are colored with the vertices of H (D is an H-colored digraph). V(D) and A(D) will denote the sets of vertices and arcs of D respectively.
Hortensia Galeana-Sánchez +1 more
doaj +1 more source
Vertices with the second neighborhood property in Eulerian digraphs [PDF]
Opuscula Mathematica, 2019 The Second Neighborhood Conjecture states that every simple digraph has a vertex whose second out-neighborhood is at least as large as its first out-neighborhood, i.e. a vertex with the Second Neighborhood Property.
Michael Cary
doaj +1 more source
Graph partitioning: an updated survey
AKCE International Journal of Graphs and Combinatorics, 2023 Graph partitioning problem, which is one of the most important topics in graph theory, usually asks for a partition of the vertex set of a graph into pairwise disjoint subsets with various requirements. It comes from the well-known Max-Cut Problem: Given
Shufei Wu, Jianfeng Hou
doaj +1 more source
Toward Wojda's conjecture on digraph packing [PDF]
Opuscula Mathematica, 2017 Given a positive integer \(m\leq n/2\), Wojda conjectured in 1985 that if \(D_1\) and \(D_2\) are digraphs of order \(n\) such that \(|A(D_1)|\leq n-m\) and \(|A(D_2)|\leq 2n-\lfloor n/m\rfloor-1\) then \(D_1\) and \(D_2\) pack.
Jerzy Konarski, Andrzej Żak
doaj +1 more source