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Elusive extremal graphs [PDF]

open access: yesProceedings 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 ...
Grzesik, Andrzej   +2 more
core   +8 more sources

Tight upper bound on the maximum anti-forcing numbers of graphs [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2017
Let $G$ be a simple graph with a perfect matching. Deng and Zhang showed that the maximum anti-forcing number of $G$ is no more than the cyclomatic number.
Lingjuan Shi, Heping Zhang
doaj   +3 more sources

On some interconnections between combinatorial optimization and extremal graph theory [PDF]

open access: yesYugoslav Journal of Operations Research, 2004
The uniting feature of combinatorial optimization and extremal graph theory is that in both areas one should find extrema of a function defined in most cases on a finite set.
Cvetković Dragoš M.   +2 more
doaj   +3 more sources

Extremal Optimization for Graph Partitioning [PDF]

open access: yesPhysical Review E, 2001
Extremal optimization is a new general-purpose method for approximating solutions to hard optimization problems. We study the method in detail by way of the NP-hard graph partitioning problem.
A. K. Hartmann   +44 more
core   +3 more sources

Capture-Time Extremal Cop-Win Graphs

open access: yesDiscussiones 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
doaj   +1 more source

On symmetric division deg index of unicyclic graphs and bicyclic graphs with given matching number

open access: yesAIMS Mathematics, 2021
Nowadays, it is an important task to find extremal values on any molecular descriptor with respect to different graph parameters. In a molecular graph, the vertices represent the atoms and the edges represent the chemical bonds in the terms of graph ...
Xiaoling Sun, Yubin Gao, Jianwei Du
doaj   +1 more source

On the Boundary of Incidence Energy and Its Extremum Structure of Tricycle Graphs

open access: yesFrontiers 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
doaj   +1 more source

The Signless Laplacian Estrada Index of Unicyclic Graphs [PDF]

open access: yesMathematics Interdisciplinary Research, 2017
‎For a simple graph G‎, ‎the signless Laplacian Estrada index is defined as SLEE(G)=∑ni=1eqi‎, ‎where q1‎, ‎q2‎,...‎, ‎qn are the eigenvalues of the signless Laplacian matrix of G‎.
Hamid Reza Ellahi   +3 more
doaj   +1 more source

A note on the Ramsey numbers for theta graphs versus the wheel of order 5

open access: yesAKCE International Journal of Graphs and Combinatorics, 2018
The study of exact values and bounds on the Ramsey numbers of graphs forms an important family of problems in the extremal graph theory. For a set of graphs S and a graph F , the Ramsey number R (S , F) is the smallest positive integer r such that for ...
Mohammed M.M. Jaradat   +3 more
doaj   +2 more sources

On the eccentric connectivity coindex in graphs

open access: yesAIMS Mathematics, 2022
The well-studied eccentric connectivity index directly consider the contribution of all edges in a graph. By considering the total eccentricity sum of all non-adjacent vertex, Hua et al.
Hongzhuan Wang, Xianhao Shi, Ber-Lin Yu
doaj   +1 more source

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