两类特殊三圈图的正负惯性指数和零度  

Positive and negative inertia indexes and nullity of two special kinds of tricyclic graphs

作　　者：杨陈[1] 马海成[1] 

机构地区：[1]青海民族大学数学系,青海西宁810007

出　　处：《山东大学学报（理学版）》2015年第2期32-37,共6页Journal of Shandong University(Natural Science)

基　　金：青海省自然科学基金资助项目(2011-Z-911)

摘　　要：讨论了Ⅰ-型三圈图和Ⅱ-型三圈图的正负惯性指数和零度问题。主要通过删除悬挂的树和压缩内部路等方法,给出了两类特殊三圈图的正负惯性指数和零度的计算方法:Ⅰ-型三圈图的正负惯性指数(零度)等于一些树和一些双圈图(或单圈图或树)的正负惯性指数(零度)之和;Ⅱ-型三圈图的正负惯性指数(零度)等于一些树和一些简单三圈图的正负惯性指数(零度)之和,对于点数较少的三圈图的正负惯性指数和零度利用软件Matlab计算得到。The problem how to calculate the positive and negative inertia indexes and nullity of Ⅰ-type and Ⅱ-type tricyclic graphs are discussed. By deleting pendant trees and compressing internal paths,a method of calculating the positive and negative inertia indexes and nullity of the two kinds of tricyclic graphs is given. It is proved that the positive and negative inertia indexes and nullity of Ⅰ-type tricyclic graphs equal to the sum of some trees and bicyclic graphs（ or unicyclic graphs or trees）,respectively; the positive and negative inertia indexes and nullity of Ⅱ-type tricyclic graphs equal to the sum of some trees and simple tricyclic graphs,and the positive and negative inertia indexes and nullity of simple tricyclic graphs can be calculated by M atlab.

关 键 词：三圈图 正惯性指数 负惯性指数 零度 

分 类 号：O157.5[理学—数学]