Results 1 to 10 of about 2,905 (83)
On game chromatic number of oriented network graphs
AKCE International Journal of Graphs and CombinatoricsIn this paper, we determine the game chromatic number of oriented honeycomb network graphs and oriented cube connected cycle network graphs.
Alagammai Renganathan, V. Vijayalakshmi
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On the existence and non-existence of improper homomorphisms of oriented and $2$-edge-coloured graphs to reflexive targets [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 We consider non-trivial homomorphisms to reflexive oriented graphs in which some pair of adjacent vertices have the same image. Using a notion of convexity for oriented graphs, we study those oriented graphs that do not admit such homomorphisms. We fully
Christopher Duffy, Sonja Linghui Shan
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Strong oriented chromatic number of planar graphs without short cycles [PDF]
Discrete Mathematics & Theoretical Computer Science, 2008 Let M be an additive abelian group. A strong oriented coloringof an oriented graph G is a mapping φ from V(G) to M such that (1) φ(u) ≠ φ(v) whenever uv is an arc in G and (2) φ(v) - φ(u) ≠ -(φ(t) - φ(z)) whenever uv and zt are two arcs in
Mickaël Montassier +2 more
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Acyclic, Star and Oriented Colourings of Graph Subdivisions [PDF]
Discrete Mathematics & Theoretical Computer Science, 2005 Let G be a graph with chromatic number χ (G). A vertex colouring of G is \emphacyclic if each bichromatic subgraph is a forest. A \emphstar colouring of G is an acyclic colouring in which each bichromatic subgraph is a star forest. Let χ _a(G) and χ _s(G)
David R. Wood
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Oriented Chromatic Number of Cartesian Products Pm □ Pn and Cm □ Pn
Discussiones Mathematicae Graph Theory, 2022 We consider oriented chromatic number of Cartesian products of two paths Pm □ Pn and of Cartesian products of paths and cycles, Cm □ Pn. We say that the oriented graph G→\vec G is colored by an oriented graph H→\vec H if there is a homomorphism from G ...
Nenca Anna
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Negative results on acyclic improper colorings [PDF]
Discrete Mathematics & Theoretical Computer Science, 2005 Raspaud and Sopena showed that the oriented chromatic number of a graph with acyclic chromatic number $k$ is at most $k2^{k-1}$. We prove that this bound is tight for $k \geq 3$.
Pascal Ochem
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A model of colour appearance based on efficient coding of natural images.
PLoS Computational Biology, 2023 An object's colour, brightness and pattern are all influenced by its surroundings, and a number of visual phenomena and "illusions" have been discovered that highlight these often dramatic effects.
Jolyon Troscianko, Daniel Osorio
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The oriented chromatic number of edge-amalgamation of cycle graph
Indonesian Journal of Combinatorics, 2019 An oriented k − coloring of an oriented graph G⃗ is a partition of V(G⃗) into k color classes such that no two adjacent vertices belong to the same color class, and all the arcs linking the two color classes have the same direction.
Dina Eka Nurvazly +2 more
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Oriented Coloring on Recursively Defined Digraphs
Algorithms, 2019 Coloring is one of the most famous problems in graph theory. The coloring problem on undirected graphs has been well studied, whereas there are very few results for coloring problems on directed graphs. An oriented k-coloring of an oriented graph G =
Frank Gurski +2 more
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Oriented Incidence Colourings of Digraphs
Discussiones Mathematicae Graph Theory, 2019 Brualdi and Quinn Massey [6] defined incidence colouring while study- ing the strong edge chromatic index of bipartite graphs. Here we introduce a similar concept for digraphs and define the oriented incidence chromatic number.
Duffy Christopher +3 more
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