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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, A J Radcliffe
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Extremal graphs for the odd prism
Discrete MathematicsThe Turán number $\mathrm{ex}(n,H)$ of a graph $H$ is the maximum number of edges in an $n$-vertex graph which does not contain $H$ as a subgraph. The Turán number of regular polyhedrons was widely studied in a series of works due to Simonovits. In this paper, we shall present the exact Turán number of the prism $C_{2k+1}^{\square} $, which is defined ...
Xiaocong He, Lihua Feng
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On Eccentricity Version of Zagreb Coindices [PDF]
Mathematics Interdisciplinary Research, 2021 The eccentric connectivity coindex has recently been introduced (Hua and Miao, 2019) as the total eccentricity sum of all pairs of non-adjacent vertices in a graph.
Mahdieh Azari
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Proceedings of the London Mathematical Society, 2020 We study the uniqueness of optimal solutions to extremal graph theory problems. Lovasz conjectured that every finite feasible set of subgraph density constraints can be extended further by a finite set of density constraints so that the resulting set is satisfied by an asymptotically unique graph.
Grzesik, Andrzej +2 more
openaire +6 more sources
Capture-Time Extremal Cop-Win Graphs
Discussiones Mathematicae Graph Theory, 2021 We investigate extremal graphs related to the game of Cops and Robbers. We focus on graphs where a single cop can catch the robber; such graphs are called cop-win.
Offner David, Ojakian Kerry
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Construction Algorithm of Given Girth Graphs Based on Quantum Evolution [PDF]
Jisuanji gongcheng, 2017 To construct an extremal graph with a given girth is still a challenging problem of graph theory.Especially when the vertex number increasex combination explosion will appear.Thus,this paper proposes an algorithm for constructing graphs with given girth ...
FENG Xiaohua,SUN Yongqi
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Extremal K_(s,t)-free bipartite graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2008 Graphs and ...
Camino Balbuena +3 more
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Extremal properties of distance-based graph invariants for $k$-trees [PDF]
Mathematica Bohemica, 2018 Sharp bounds on some distance-based graph invariants of $n$-vertex $k$-trees are established in a unified approach, which may be viewed as the weighted Wiener index or weighted Harary index.
Minjie Zhang, Shuchao Li
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On the Boundary of Incidence Energy and Its Extremum Structure of Tricycle Graphs
Frontiers in Physics, 2020 With the wide application of graph theory in circuit layout, signal flow chart and power system, more and more attention has been paid to the network topology analysis method of graph theory.
Hongyan Lu, Zhongxun Zhu
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The Aα-spectral radius of complements of bicyclic and tricyclic graphs with n vertices
Special Matrices, 2021 Recently, the extremal problem of the spectral radius in the class of complements of trees, unicyclic graphs, bicyclic graphs and tricyclic graphs had been studied widely.
Chen Chaohui +2 more
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