Results 21 to 30 of about 9,271 (238)
A digraph equation for homomorphic images
International Journal of Mathematics and Mathematical Sciences, 1986 The definitions of a homomorphism and a contraction of a graph are generalized to digraphs. Solutions are given to the graph equation ϕ(D)¯=θϕ(D¯).
Robert D. Girse, Richard A. Gillman
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Reducing Graph Parameters by Contractions and Deletions [PDF]
Algorithmica, 2023 AbstractWe consider the following problem: for a given graph G and two integers k and d, can we apply a fixed graph operation at most k times in order to reduce a given graph parameter $$\pi $$ π by at least d? We show that this problem is NP-hard when the parameter is the independence number and the graph operation ...
Felicia Lucke, Felix Mann
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Homomorphisms and related contractions of graphs
International Journal of Mathematics and Mathematical Sciences, 1988 For every homomorphism ϕ of a graph G there exists a contraction θϕ on G¯, the complement of G. Here we study the graph equation ϕ(G)=θϕ(G¯). In the course of our work we show that Hadwiger's Conjecture is true for every self-complementary graph.
Robert D. Girse, Richard A. Gillman
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On graph contractions and induced minors [PDF]
Discrete Applied Mathematics, 2012 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Pim van 't Hof +4 more
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Homomorphisms of complete n-partite graphs
International Journal of Mathematics and Mathematical Sciences, 1986 It is shown that for every homomorphism ϕ of a graph G there exists a contraction θϕ on G¯, the complement of G, such that ϕ(G)¯=θϕ(G¯) if and only if G is a complete n-partite graph.
Robert D. Girse
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Fixed Points of -Type Quasi-Contractions on Graphs
Abstract and Applied Analysis, 2013 Recently, fixed point theory on graphs has been considered by many authors. In this paper, by combining some ideas in some published papers and introducing -type quasi-contractions, we give some fixed point results for -type quasi-contractions on graphs.
R. H. Haghi, Sh. Rezapour, N. Shahzad
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Contracting Graphs to Split Graphs and Threshold Graphs
CoRR, 2013 14 pages, 4 ...
Leizhen Cai, Chengwei Guo
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Applications of Multivalued Contractions on Graphs to Graph-Directed Iterated Function Systems
Abstract and Applied Analysis, 2015 We apply a fixed point result for multivalued contractions on complete metric spaces endowed with a graph to graph-directed iterated function systems.
T. Dinevari, M. Frigon
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Contracting a Planar Graph Efficiently
CoRR, 2017 We present a data structure that can maintain a simple planar graph under edge contractions in linear total time. The data structure supports adjacency queries and provides access to neighbor lists in $O(1)$ time. Moreover, it can report all the arising self-loops and parallel edges.
Jacob Holm +5 more
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PLoS ONE, 2020 BackgroundCatecholaminergic polymorphic ventricular tachycardia (CPVT) is a severe inherited arrhythmic disease associated with a risk of syncope and sudden cardiac death (SCD).AimsWe aimed at identifying RYR2 P2328S founder mutation carriers and ...
Mikael Koponen +9 more
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