Results 11 to 20 of about 238 (165)
Graph Powers and Graph Homomorphisms [PDF]
The Electronic Journal of Combinatorics, 2010 In this paper, we investigate some basic properties of fractional powers. In this regard, we show that for any non-bipartite graph $G$ and positive rational numbers ${2r+1\over 2s+1} < {2p+1\over 2q+1}$, we have $G^{2r+1\over 2s+1} < G^{2p+1\over 2q+1}$. Next, we study the power thickness of $G$, that is, the supremum of rational numbers ${2r+
Hossein Hajiabolhassan, Ali Taherkhani
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The Dichotomy of Evaluating Homomorphism-Closed Queries on Probabilistic Graphs [PDF]
Logical Methods in Computer Science, 2022 We study the problem of query evaluation on probabilistic graphs, namely, tuple-independent probabilistic databases over signatures of arity two. We focus on the class of queries closed under homomorphisms, or, equivalently, the infinite unions of ...
Antoine Amarilli, İsmail İlkan Ceylan
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Exact algorithm for graph homomorphism and locally injective graph homomorphism [PDF]
Information Processing Letters, 2014 For graphs $G$ and $H$, a homomorphism from $G$ to $H$ is a function $φ\colon V(G) \to V(H)$, which maps vertices adjacent in $G$ to adjacent vertices of $H$. A homomorphism is locally injective if no two vertices with a common neighbor are mapped to a single vertex in $H$.
Rz{\ka}żewski, Paweł +1 more
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Infinite limits and folding [PDF]
Discrete Mathematics & Theoretical Computer Science, 2005 We study infinite limits of graphs generated by the duplication model for biological networks. We prove that with probability 1, the sole nontrivial connected component of the limits is unique up to isomorphism. We describe certain infinite deterministic
Anthony Bonato, Jeannette Janssen
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Small Promise CSPs that reduce to large CSPs [PDF]
Logical Methods in Computer Science, 2022 For relational structures A, B of the same signature, the Promise Constraint Satisfaction Problem PCSP(A,B) asks whether a given input structure maps homomorphically to A or does not even map to B.
Alexandr Kazda, Peter Mayr, Dmitriy Zhuk
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Reconfiguring graph homomorphisms on the sphere [PDF]
European Journal of Combinatorics, 2020 Given a loop-free graph $H$, the reconfiguration problem for homomorphisms to $H$ (also called $H$-colourings) asks: given two $H$-colourings $f$ of $g$ of a graph $G$, is it possible to transform $f$ into $g$ by a sequence of single-vertex colour changes such that every intermediate mapping is an $H$-colouring?
Jae-Baek Lee +2 more
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Ideals of Graph Homomorphisms [PDF]
Annals of Combinatorics, 2012 In combinatorial commutative algebra and algebraic statistics many toric ideals are constructed from graphs. Keeping the categorical structure of graphs in mind we give previous results a more functorial context and generalize them by introducing the ideals of graph homomorphisms.
Engström Alexander, Norén Patrik
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Finding the Number of Weak Homomorphisms of Paths
Journal of Mathematics, 2022 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. In this paper, we provide an algorithm to determine the number of weak homomorphisms of paths.
Tawatchai Pomsri +2 more
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Novel Concepts in Vague Graphs with Application in Hospital’s Management System
Journal of Mathematics, 2022 Many problems of practical interest can be modeled and solved by using vague graph (VG) algorithms. Vague graphs, belonging to the fuzzy graphs (FGs) family, have good capabilities when faced with problems that cannot be expressed by FGs.
Xiaolong Shi +4 more
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Homomorphisms of planar signed graphs to signed projective cubes [PDF]
Discrete Mathematics & Theoretical Computer Science, 2013 We conjecture that every signed graph of unbalanced girth 2g, whose underlying graph is bipartite and planar, admits a homomorphism to the signed projective cube of dimension 2g1.
Reza Naserasr +2 more
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