Results 21 to 30 of about 514 (184)
Homomorphisms of signed graphs: An update
European Journal of Combinatorics, 2021 A signed graph is a graph together with an assignment of signs to the edges. A closed walk in a signed graph is said to be positive (negative) if it has an even (odd) number of negative edges, counting repetition. Recognizing the signs of closed walks as one of the key structural properties of a signed graph, we define a homomorphism of a signed graph $
Naserasr, Reza +2 more
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Graph Homomorphism Convolution
CoRR, 2020 In this paper, we study the graph classification problem from the graph homomorphism perspective. We consider the homomorphisms from $F$ to $G$, where $G$ is a graph of interest (e.g. molecules or social networks) and $F$ belongs to some family of graphs (e.g. paths or non-isomorphic trees).
Hoang NT, Takanori Maehara
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On index coding and graph homomorphism [PDF]
2014 IEEE Information Theory Workshop (ITW 2014), 2014 In this work, we study the problem of index coding from graph homomorphism perspective. We show that the minimum broadcast rate of an index coding problem for different variations of the problem such as non-linear, scalar, and vector index code, can be upper bounded by the minimum broadcast rate of another index coding problem when there exists a ...
Javad B. Ebrahimi +1 more
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Homomorphic Preimages of Geometric Paths
Discussiones Mathematicae Graph Theory, 2018 A graph G is a homomorphic preimage of another graph H, or equivalently G is H-colorable, if there exists a graph homomorphism f : G → H. A geometric graph Ḡ is a simple graph G together with a straight line drawing of G in the plane with the vertices in
Cockburn Sally
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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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Notion of Complex Spherical Dombi Fuzzy Graph and Its Application in Decision-Making Problems
IEEE Access, 2023 The complex spherical fuzzy graph (CSFG), which extends the concept of a spherical fuzzy graph (SFG), proves to be a more effective means of depicting relationships among diverse objects when these relationships are subject to uncertainty.
Ehsan Mehboob Ahmed Butt +4 more
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On weighted graph homomorphisms [PDF]
, 2004 For given graphs $G$ and $H$, let $|Hom(G,H)|$ denote the set of graph homomorphisms from $G$ to $H$. We show that for any finite, $n$-regular, bipartite graph $G$ and any finite graph $H$ (perhaps with loops), $|Hom(G,H)|$ is maximum when $G$ is a disjoint union of $K_{n,n}$'s. This generalizes a result of J.
David J. Galvin, Prasad Tetali
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Homomorphisms on Graph-Walking Automata
, 2022 Graph-walking automata (GWA) are a model for graph traversal using finite-state control: these automata move between the nodes of an input graph, following its edges. This paper investigates the effect of node-replacement graph homomorphisms on recognizability by these automata.
Olga Martynova 0001, Alexander Okhotin
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Graph Homomorphisms between Trees [PDF]
The Electronic Journal of Combinatorics, 2014 In this paper we study several problems concerning the number of homomorphisms of trees. We begin with an algorithm for the number of homomorphisms from a tree to any graph. By using this algorithm and some transformations on trees, we study various extremal problems about the number of homomorphisms of trees.
Csikvari, Peter, Lin, Zhicong
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A Homomorphic Polynomial for Oriented Graphs
The Electronic Journal of Combinatorics, 2023 In this article, we define a function that counts the number of (onto) homomorphisms of an oriented graph. We show that this function is always a polynomial and establish it as an extension of the notion of chromatic polynomials. We study algebraic properties of this function.
Sandip Das 0001 +3 more
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