摘要
设P(G,λ)是图G的色多项式,如果任意与图G的色多项式相等(P(G,λ)=P(H,λ))的图H都与图G同构(G≌H),则称图G是色唯一图.这里,通过比较图的三角形子图和无弦四边形的个数,完全解决了一类完全三部图K(n-k,n-3,n)的色唯一性问题,证明了,若n≥k+2≥5,则完全三部图K(n-k,n-3,n)是色唯一图.
Let P(G,λ)be the chromatic polynomial of a graph G.A graph Gis chromatically unique if for any graph H,P(H,λ)=P(G,λ)implies G≌H.Here,by comparing the number of the triangular subgraphs and the number of the quadrangular subgraphs without chords,the chromatic uniqueness problem of the complete tripartite graphs K(n-k,n-3,n)was completely solved.It was proved that K(n-k,n-3,n)is chromatically unique if n≥k+2≥5.
作者
徐利民
杨志林
XU Limin;YANG Zhilin(Department of Humanities Education,Huainan Vocational and Technical College,Huainan 232001,China;School of Mathematics,Hefei University of Technology,Hefei 230009,China)
基金
Supported by the Natural Science Research Project of Higher Education of Anhui(KJ2015A404)
关键词
完全三部图
色唯一性
三角形子图
无弦四边形子图
complete tripartite graph
chromatically uniqueness
triangular subgraph
quadrangular subgraph without chords