Results 151 to 160 of about 514 (184)
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Homomorphisms of Signed Graphs
Journal of Graph Theory, 2014AbstractA signed graph is a graph G together with an assignment of signs + and − to all the edges of G where Σ is the set of negative edges. Furthermore and are considered to be equivalent if the symmetric difference of Σ1 and Σ2 is an edge cut of G. Naturally arising from matroid theory, several notions of graph theory, such as the theory of minors
Reza Naserasr +2 more
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Journal of Graph Theory, 2011
AbstractA geometric graph is a simple graph drawn on points in the plane, in general position, with straightline edges. A geometric homomorphism from to is a vertex map that preserves adjacencies and crossings. This work proves some basic properties of geometric homomorphisms and defines the geochromatic number as the minimum n so that there is a ...
Debra L. Boutin, Sally Cockburn
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AbstractA geometric graph is a simple graph drawn on points in the plane, in general position, with straightline edges. A geometric homomorphism from to is a vertex map that preserves adjacencies and crossings. This work proves some basic properties of geometric homomorphisms and defines the geochromatic number as the minimum n so that there is a ...
Debra L. Boutin, Sally Cockburn
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Homomorphisms and inverse homomorphisms on graph-walking automata
Theoretical Computer Science, 2023zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Olga Martynova 0001, Alexander Okhotin
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2004
Abstract This is a book about graph homomorphisms, intended to introduce this exciting topic to a wide audience. It attempts to bring together what the authors see as the highlights of the theory and its many applications, and could be read as a sampler of this rich theory, and its most interesting results, techniques, and ...
Pavol Hell, Jaroslav Nesetril
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Abstract This is a book about graph homomorphisms, intended to introduce this exciting topic to a wide audience. It attempts to bring together what the authors see as the highlights of the theory and its many applications, and could be read as a sampler of this rich theory, and its most interesting results, techniques, and ...
Pavol Hell, Jaroslav Nesetril
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Dual graph homomorphism functions
Journal of Combinatorial Theory - Series A, 2010 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
László Lovasz, Alexander Schrijver
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Extremal Graphs for Homomorphisms II
Journal of Graph Theory, 2013AbstractExtremal problems for graph homomorphisms have recently become a topic of much research. Let denote the number of homomorphisms from G to H. A natural set of problems arises when we fix an image graph H and determine which graph(s) G on n vertices and m edges maximize .
Jonathan Cutler, A. J. Radcliffe
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Exact Algorithms for Graph Homomorphisms
Theory of Computing Systems, 2005Graph homomorphism, also called H-coloring, is a natural generalization of graph coloring: There is a homomorphism from a graph G to a complete graph on k vertices if and only if G is k-colorable. During recent years the topic of exact (exponential-time) algorithms for NP-hard problems in general, and for graph coloring in particular, has led to ...
Fedor V. Fomin +2 more
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The Homomorphism Structure of Classes of Graphs
Combinatorics, Probability and Computing, 1999We consider three aspects of homomorphisms of graphs and hypergraphs which are related to the structure of colour classes: (1) density, (2) the fractal property and (3) the generation of colour classes. In particular, we prove a density theorem for hypergraphs and show that, for connected oriented graphs, all jumps are balanced (and give an example ...
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2016
Aside from ordered sets, the fixed point property has been investigated in other settings. On one hand, the fixed point property is most likely originated in topology. (See Exercise 6-1 for the topological fixed point property.) On the other hand, in any branch of mathematics in which the underlying structures have a natural type of morphism, we can ...
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Aside from ordered sets, the fixed point property has been investigated in other settings. On one hand, the fixed point property is most likely originated in topology. (See Exercise 6-1 for the topological fixed point property.) On the other hand, in any branch of mathematics in which the underlying structures have a natural type of morphism, we can ...
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Homomorphisms of graphs into odd cycles
Journal of Graph Theory, 1988AbstractWe give a class of graphs G for which there exists a homomorphism (= adjacency preserving map) from V(G) to V(C), where C is the shortest odd cycle in G, thereby extending a result of Albertson, Catlin, and Gibbons. Our class of graphs is characterized by the following property: For each odd subdivision G′ of G there exists a homomorphic map ...
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