Results 1 to 10 of about 238 (165)
Entropy, Graph Homomorphisms, and Dissociation Sets [PDF]
Entropy, 2023 Given two graphs G and H, the mapping of f:V(G)→V(H) is called a graph homomorphism from G to H if it maps the adjacent vertices of G to the adjacent vertices of H.
Ziyuan Wang, Jianhua Tu, Rongling Lang
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Extremal graphs for homomorphisms [PDF]
Journal of Graph Theory, 2011 Summary: The study of graph homomorphisms has a long and distinguished history, with applications in many areas of graph theory. There has been recent interest in counting homomorphisms, and in particular on the question of finding upper bounds for the number of homomorphisms from a graph \(G\) into a fixed image graph \(H\).
Jonathan Cutler
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An Algorithm for the Numbers of Homomorphisms from Paths to Rectangular Grid Graphs
Mathematics, 2023 Let G and H be graphs. A mapping f from the vertices of G to the vertices of H is known as a homomorphism from G to H if, for every pair of adjacent vertices x and y in G, the vertices f(x) and f(y) are adjacent in H.
Hatairat Yingtaweesittikul +2 more
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Homomorphisms of Strongly Regular Graphs [PDF]
Electronic Notes in Discrete Mathematics, 2016 We prove that if G and H are primitive strongly regular graphs with the same parameters and φ
David Robérson
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Homomorphisms of derivative graphs
Discrete Mathematics, 1971 AbstractThe derivative graphs and their homomorphisms are studied. Inspirated by the Whitney theorem on automorphisms, we are considering endomorphisms of a graph in their relationship to endomorphisms of its derivative graph. Particularly, we characterize in this connection the graphs with the best endomorphisms.
Jaroslav Nešetřil
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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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Weighted Graphs and Fuzzy Graphs [PDF]
Transactions on Fuzzy Sets and Systems, 2023 It has been shown in literature that in the two-dimensional case, the lattices of truth values considered are pairwise isomorphic, and so are the corresponding families of fuzzy sets.
John Mordeson +2 more
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Formulas for the Number of Weak Homomorphisms from Paths to Ladder Graphs and Stacked Prism Graphs
Journal of Mathematics, 2023 Let G and H be graphs. A mapping f from VG to VH is called a weak homomorphism from G to H if fx=fy or fx,fy∈EH whenever x,y∈EG. A ladder graph is the Cartesian product of two paths, where one of the paths has only one edge.
Hatairat Yingtaweesittikul +2 more
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Homomorphism–homogeneous graphs [PDF]
Journal of Graph Theory, 2010 AbstractWe answer two open questions posed by Cameron and Nesetril concerning homomorphism–homogeneous graphs. In particular we show, by giving a characterization of these graphs, that extendability to monomorphism or to homomorphism leads to the same class of graphs when defining homomorphism–homogeneity.
Momchil Rusinov, Pascal Schweitzer
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On the Complexity of Digraph Colourings and Vertex Arboricity [PDF]
Discrete Mathematics & Theoretical Computer Science, 2020 It has been shown by Bokal et al. that deciding 2-colourability of digraphs is an NP-complete problem. This result was later on extended by Feder et al. to prove that deciding whether a digraph has a circular $p$-colouring is NP-complete for all rational
Winfried Hochstättler +2 more
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