JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE) ›› 2015, Vol. 50 ›› Issue (02): 32-37.doi: 10.6040/j.issn.1671-9352.0.2014.267

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

YANG Chen, MA Hai-cheng   

  1. Department of Mathematics, Qinghai University for Nationalities, Xining 810007, Qinghai, China
  • Received:2014-06-11 Revised:2014-10-14 Online:2015-02-20 Published:2015-01-27

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Abstract: 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 Matlab.

Key words: negative inertia index, tricyclic graph, positive inertia index, nullity

CLC Number: 

  • O157.5
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