On the geometric-arithmetic index of a graph

被引:10
|
作者
Chen, Yin [1 ]
Wu, Baoyindureng [2 ]
机构
[1] Xiamen Univ, Sch Math Sci, Xiamen 361005, Peoples R China
[2] Xinjiang Univ, Coll Math & Syst Sci, Urumqi 830046, Xinjiang, Peoples R China
关键词
Geometric-arithmetic index; Chromatic number; Clique number; CHROMATIC NUMBER; BOUNDS;
D O I
10.1016/j.dam.2018.06.021
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Very recently, Aouchiche and Hansen gave an upper bound on the ratio of GA/chi of the geometric-arithmetic index GA(G) and the chromatic number chi(G) of a graph. Furthermore, they proposed several conjectures on the relation between geometric-arithmetic index and chromatic number, and clique number. In this note, we disprove four of those conjectures. In addition, we present a sufficient condition for an edge e is an element of E(G) with GA(G - e) < GA(G). (C) 2018 Elsevier B.V. All rights reserved.
引用
收藏
页码:268 / 273
页数:6
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