Results 41 to 50 of about 34,455 (233)
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
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Journal of Algebra Combinatorics Discrete Structures and Applications, 2022 A $(0,1)$-labelling of a set is said to be {\em friendly} if approximately one half the elements of the set are labelled 0 and one half labelled 1. Let $g$ be a labelling of the edge set of a graph that is induced by a labelling $f$ of the vertex set. If both $g$ and $f$ are friendly then $g$ is said to be a {\em cordial} labelling of the graph.
Beasley, Leroy +3 more
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Perfect directed codes in Cayley digraphs
AIMS MathematicsA perfect directed code (or an efficient twin domination) of a digraph is a vertex subset where every other vertex in the digraph has a unique in- and a unique out-neighbor in the subset. In this paper, we show that a digraph covers a complete digraph if
Yan Wang , Kai Yuan , Ying Zhao
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International Journal of Mathematics and Mathematical Sciences, 1993 The antipodal graph of a graph G, denoted by A(G), has the same vertex set as G with an edge joining vertices u and v if d(u,v) is equal to the diameter of G.
Garry Johns, Karen Sleno
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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
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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
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Advances in Mathematics, 1996 The author applies the language of Joyal's species to enumeration problems of digraphs using the machinery of coloured species, see, e.g., the author and \textit{O. Nava} [J. Comb. Theory, Ser. A 64, No. 1, 102-129 (1993; Zbl 0787.05095)]. A species over digraphs is defined as a functor from the category of digraphs to the category of finite sets and ...
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Discrete Mathematics, 2006 Let $ (x,y)$ be a bivariate polynomial with complex coefficients. The zeroes of $ (x,y)$ are given a combinatorial structure by considering them as arcs of a directed graph $G( )$. This paper studies some relationship between the polynomial $ (x,y)$ and the structure of $G( )$.
Josep M. Brunat, Antonio Montes
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Extremal Digraphs Avoiding Distinct Walks of Length 4 with the Same Endpoints
Discussiones Mathematicae Graph Theory, 2022 Let n ≥ 8 be an integer. We characterize the extremal digraphs of order n with the maximum number of arcs avoiding distinct walks of length 4 with the same endpoints.
Lyu Zhenhua
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On (4,2)-digraph Containing a Cycle of Length 2 [PDF]
, 2000 A diregular digraph is a digraph with the in-degree and out-degree of all vertices is constant. The Moore bound for a diregular digraph of degree d and diameter k is M_{d,k}=l+d+d^2+...+d^k.
Baskoro, Edy Tri, Iswadi, Hazrul
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