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NIC-平面图中的轻边存在性及其定向染色
引用本文:刘维婵.NIC-平面图中的轻边存在性及其定向染色[J].计算机工程与应用,2018,54(7):62-65.
作者姓名:刘维婵
作者单位:西安电子科技大学 数学与统计学院,西安 710071
摘    要:如果一个图G]画在平面上有交叉c],则该交叉可以与产生它的两条边所关联的4个顶点所构成的点集合{v1,v2,v3,v4}]建立一个对应关系θ:c→{v1,v2,v3,v4}]。如果对于G]中任何两个不同的交叉(如果存在的话)c1]与c2]都有|θ(c1)?θ(c2)|≤1],则称图G]为NIC-平面图。证明了每个围长至少为5且最小度为4的NIC-平面图含有一条边,其2个顶点的度数都是4,从而每个围长至少为5的NIC-平面图的定向染色数至多为67。

关 键 词:NIC-平面图  轻边  权转移方法  定向染色  

Existence of light edge and oriented coloring of NIC-planar graphs
LIU Weichan.Existence of light edge and oriented coloring of NIC-planar graphs[J].Computer Engineering and Applications,2018,54(7):62-65.
Authors:LIU Weichan
Affiliation:School of Mathematics and Statistics, Xidian University, Xi’an 710071, China
Abstract:If there exists a crossing c in a graph G drawn on the plane, this crossing induces a function θ:c→]{v1,v2,]v3,v4}], where {v1,v2,v3,v4}] is a set of four vertices that are the ones incident with the two crossed edges generating the crossing c. If |θ(c1)∩θ(c2)|≤1] for any two distinct crossings c1 and c2(if exist) in G, G is a NIC-planar graph. It is proven that every NIC-planar graph with girth at least 5 and minimum degree 4 contains an edge with the degrees of the two adjacent vertices both being 4. As a consequence, it deduces that the oriented chromatic number of any NIC-planar graph with girth at least 5 is at most 67.
Keywords:NIC-planar graph  light edge  discharging method  oriented coloring  
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