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新疆大学数学与系统科学学院
Published:2018
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[1]李中华,吴宝音都仍,安新慧,等.列表双临界图(英文)[J],2018,35(01):1-3.
[1]李中华,吴宝音都仍,安新慧,等.列表双临界图(英文)[J],2018,35(01):1-3. DOI: 10.13568/j.cnki.651094.2018.01.001.
DOI:10.13568/j.cnki.651094.2018.01.001.
G是k-可着色的连通图
如果对于G中的所有边uv
都有G-u-v是(k-2)-可着色的
则称图G是双临界图.由Erdo?s和Lova′sz提出了一个长期未能解决的猜想:完全图是唯一的双临界图[1].连通图G称为边双临界图
如果G中包含多对不相邻的边
并且对于任意一对不相邻的边e1
e2
都有χ(G-e1-e2)=χ(G)-2
其中χ(G)表示图G的色数.Kawarabayashi等人[2]及后来的Lattanzio[3]证明了完全图是唯一的边双临界图.文章证明了在图G中
对于任意的两个点u
v∈V(G)
如果ch(G-u-v)=ch(G)-2
则图G是完全图
其中ch(G)表示G的选择数
还证明了完全图是唯一的列表双临界图.
A connected k-chromatic graph G is double-critical if for all edges uv of G the graph G-u-v is(k-2)-colorable. A long-standing conjecture
due to Erd o?s and Lova′sz[1]
states that the complete graphs are the only double-critical graphs. A connected graph G is called edge double-critical if it contains some pairs of nonadjacent edges
and χ(G-e1-e2) =χ(G)-2 for any two nonadjacent edges e1
e2∈ E(G)
where χ(G) denotes the chromatic number of G. Kawarabayashi et al.[2]and later
Lattanzio[3]proved that the complete graphs are the only edge double-critical graphs. In this note
we show that for a graph G
if ch(G-u-v) = ch(G)-2 for any vertices u
v ∈ V(G)
then G is a complete graph
where ch(G) denotes the choice number of G. We also prove that the complete graphs are the only edge list double-critical graphs.
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