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图的Nordhaus Gaddumm型的代数连通度的界
引用本文:吕大梅,杜娟,吕嘉钧.图的Nordhaus Gaddumm型的代数连通度的界[J].浙江大学学报(理学版),2009,36(6):616-619.
作者姓名:吕大梅  杜娟  吕嘉钧
作者单位:南通大学,理学院,数学系,江苏,南通,210007
基金项目:Supported by NSFC (10671033) . The Natural Science Foundation of Nantong University (08Z003).
摘    要:设图G是n阶的单图,G'是它的补图.用a(G)表示图G的代数连通度.在很多文献中,已经研究了邻接谱半径的Nordhaus—Gaddum型的界的问题.本文进一步探讨了代数连通度的Nordhaus—Gaddum型的界.得到:对树和其他一些图,a(G)+a(G')≥1成立,并刻画了等式成立时的图的特征.根据这些结果,最后提出这样一个猜想:对n阶的单图G,有n(G)+n(G')≥1.

关 键 词:N—G型  代数连通度  

A sharp lower bound for the algebraic connectivity of the Nordhaus-Gaddumm type
L Da-mei,DU Juan,L Jia-jun.A sharp lower bound for the algebraic connectivity of the Nordhaus-Gaddumm type[J].Journal of Zhejiang University(Sciences Edition),2009,36(6):616-619.
Authors:L Da-mei  DU Juan  L Jia-jun
Institution:L(U) Da-mei,DU Juan,L(U) Jia-jun
Abstract:Let G be a simple graph with n vertices and Gc be its complement graph.Let a(G) be the algebraic connectivity of G.The bound for the spectrum of the Nordhaus-Gaddum type has been studied in many papers while this paper,the bound for the algebraic connectivity of the Nordhaus-Gaddum type is observed.For the trees and some other graphs,a(G) + a(Gc)≥1 is obtained and the graphs which achieve the bound is also characterized.As a result,the following conjecture is given: Let G be a graph of order n,then a(G)+a(Gc)≥1.
Keywords:Nordhaus-Gaddum type  algebraic connectivity  bound
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