Acta mathematica scientia,Series A ›› 2004, Vol. 4 ›› Issue (5): 530-536.

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Bidirectional Double Tracings and Maximum Genus

 HUANG Yuan-Qiu, LIU Pan-Pei, CHU Yu-Meng   

  • Online:2004-07-20 Published:2004-07-20
  • Supported by:

    数学天元青年基金(10226018)、国家自然科学基金(10271045)及湖南省教

    育厅青年基金(02B018)

Abstract:

Let G be a connected graph and L be a bidirectional double tracing of G. The authors first introduce a new invarint of G, which is called the  retracing number and denoted by ε(G).  The definition  of ε(G) is  given as follows: ε(G)=min〖DD(X〗L〖DD)〗 ε(G, L), where  ε(G, L) is the number of retracings in L, and the minimum ranges over all bidirectional double tracings of G. Then, for a connected 3regular graph G  the authors prove that ε(G) is closely related to the maximum genus γ\-M(G) of G, namely ε(G), equals to the value 2γ\-M(G)-β(G) where β(G) is the rank number of G.  Also the authors  provide an instructural characterization on thegraph G  according to the value ε(G). Thus these  may be viewed as  some  generalizations  of  Thomassen C's results.

Key words: Bidirectional double tracing, Retracing number, Betti , deficiency number, Upper embeddable, Maximum genus

CLC Number: 

  • 05C75
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