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Coloring Mixed and Directional Interval Graphs
Lecture Notes in Computer Science, 2023 A mixed graph has a set of vertices, a set of undirected egdes, and a set of directed arcs. A proper coloring of a mixed graph $G$ is a function $c$ that assigns to each vertex in $G$ a positive integer such that, for each edge $uv$ in $G$, $c(u) \ne c(v)$ and, for each arc $uv$ in $G$, $c(u) < c(v)$. For a mixed graph $G$, the chromatic number $χ(G)
Alexander Wolff +2 more
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Bivariate Chromatic Polynomials of Mixed Graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2023 The bivariate chromatic polynomial $\chi_G(x,y)$ of a graph $G = (V, E)$, introduced by Dohmen-P\"{o}nitz-Tittmann (2003), counts all $x$-colorings of $G$ such that adjacent vertices get different colors if they are $\le y$. We extend this notion to
Matthias Beck, Sampada Kolhatkar
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The gamma-Signless Laplacian Adjacency Matrix of Mixed Graphs
Theory and Applications of Graphs, 2023 The α-Hermitian adjacency matrix Hα of a mixed graph X has been recently introduced. It is a generalization of the adjacency matrix of unoriented graphs. In this paper, we consider a special case of the complex number α.
Omar Alomari +2 more
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On bipartite‐mixed graphs [PDF]
Journal of Graph Theory, 2018 AbstractMixed graphs can be seen as digraphs that have both arcs and edges (or digons, that is, two opposite arcs). In this article, we consider the case where such graphs are bipartite. As main results, we show that in this context the Moore‐like bound is attained in the case of diameter , and that bipartite‐mixed graphs of diameter do not exist.
Dalfó Simó, Cristina +2 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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The mixed page number of graphs
Theoretical Computer Science, 2022 A linear layout of a graph typically consists of a total vertex order, and a partition of the edges into sets of either non-crossing edges, called stacks, or non-nested edges, called queues. The stack (queue) number of a graph is the minimum number of required stacks (queues) in a linear layout.
Jawaherul Md. Alam +4 more
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Integral mixed circulant graphs
Discrete Mathematics, 2023 A mixed graph is said to be \textit{integral} if all the eigenvalues of its Hermitian adjacency matrix are integer. The \textit{mixed circulant graph} $Circ(\mathbb{Z}_n,\mathcal{C})$ is a mixed graph on the vertex set $\mathbb{Z}_n$ and edge set $\{ (a,b): b-a\in \mathcal{C} \}$, where $0\not\in \mathcal{C}$.
Monu Kadyan, Bikash Bhattacharjya
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Enumeration of Mixed Graphs [PDF]
Proceedings of the American Mathematical Society, 1966 and three oriented lines. An ordinary graph may be regarded as a mixed graph with no oriented lines, and an oriented graph as a mixed graph with no ordinary lines. Further, any digraph may be considered as a mixed graph by changing each symmetric pair of lines to an ordinary line.
Harary, Frank, Palmer, Edgar M.
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Incidence matrices and line graphs of mixed graphs
Special Matrices, 2023 In the theory of line graphs of undirected graphs, there exists an important theorem linking the incidence matrix of the root graph to the adjacency matrix of its line graph. For directed or mixed graphs, however, there exists no analogous result.
Abudayah Mohammad +2 more
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The Vertex-Edge Resolvability of Some Wheel-Related Graphs
Journal of Mathematics, 2021 A vertex w∈VH distinguishes (or resolves) two elements (edges or vertices) a,z∈VH∪EH if dw,a≠dw,z. A set Wm of vertices in a nontrivial connected graph H is said to be a mixed resolving set for H if every two different elements (edges and vertices) of H ...
Bao-Hua Xing +4 more
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