Chromatic Choosability of a Class of Complete Multipartite Graphs
Received:August 12, 2005  Revised:November 27, 2005
Key Words: list coloring   complete multipartite graph   chromatic choosable graph   Ohba's conjecture.  
Fund Project:the Science Foundation of the Education Department of Hebei Province (2005108).
Author NameAffiliation
SHEN Yu-fa Dept. of Math. & Phys., Hebei Normal University of Sci. & Tech., Qinhuangdao 066004, China
College of Math. \& Info. Sci., Hebei Normal University, Shijiazhuang 050016, China 
ZHENG Guo-ping Dept. of Math. & Phys., Hebei Normal University of Sci. & Tech., Qinhuangdao 066004, China 
HE Wen-jie Applied Mathematics Institute, Hebei University of Technology, Tianjin 300130, China 
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Abstract:
      A graph $G$ is called to be chromatic choosable if its choice number is equal to its chromatic number. In 2002, Ohba conjectured that every graph $G$ with $2\chi(G)+1$ or fewer vertices is chromatic choosable. It is easy to see that Ohba's conjecture is true if and only if it is true for complete multipartite graphs. But at present only for some special cases of complete multipartite graphs, Ohba's conjecture have been verified. In this paper we show that graphs $K_{6,3,2*(k-6),1*4}$ ($k\geq6$) is chromatic choosable and hence Ohba's conjecture is true for the graphs $K_{6,3,2*(k-6),1*4}$ and all complete $k$-partite subgraphs of them.
Citation:
DOI:10.3770/j.issn:1000-341X.2007.02.006
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