刘汉辉, 黄琼湘. 双圈图的极小广义Randi指标(英文)[J]. Journal of Xinjiang University (Natural Science Edition in Chinese and English), 2006, (1).DOI:
双圈图的极小广义Randi指标(英文)
摘要
图G的广义R and i′c指标定义为Rα(G)=∑uv∈E(G)Rα(uv)=∑uv∈E(G)(d(u)d(v))α
其中d(u)是顶点u的度
α是实数.胡玉梅等给出了树的广义R and i′c指标的下界及其极图
吴宝音都仍等基本上给出了单圈图的广义R and i′c指标的下界及其极图.本文讨论双圈图G的R and i′c指标.利用吴宝音都仍的方法得到:当α>0时
Rα(G)≥6.6α+(n-5).4α(这里n=G).同时确定了这样的极图.
Abstract
The general Randi(c′) index R_α(G)ofa graphGis defined byR_α(G)=_uv∈E(G)R_α(uv)=_uv∈E(G)(d(u)d(v))~α
where d(u) denotes the degree of a vertex u in G and α is an arbitrary real number.Hu
Li and Yuan gave the minimum general Randi(c′) index of trees and its extremal graph
and basically Wu and Zhang gave the minimum general Randi(c′) index of unicyclic graphs and its extremal graph. Let G be a bicyclic graph with the order n. In this paper
we use a method similar to that of Wu and Zhang to prove that R_α(G)≥6·6~α+(n-5)·4~α for α>0
and give its extremal graphs.
关键词
Keywords
references
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