摘要: 极值图论是图论中的重要内容,主要研究具有某些性质的图的极值问题。平面图的Turán数

是指具有
n个顶点的平面图
G的最大边数,其中图
G不包含
H作为一个子图。这个问题是由Dowden在2016年提出的。最近Ghosh等人研究了若干双星图的平面Turán数,并得到很多结果。在这里,我们将给出不含双星
S2,6且任意相邻两点度数之和不等于12的平面图边数的上界,即设图
G是

个顶点的平面图,图中不包含
S2,6作为子图且任意相邻两点度数之和不等于12,那么有

。
Abstract:
Extremal graph theory is an important part of graph theory, which aims to study the extremal structure of graphs with certain properties. The planar Turán number, denoted by

, is the maximum number of edges in graph
G on
n vertices, where
G does not contain
H as a subgraph. This problem was initiated by Dowden in 2016. Recently, Ghosh
et al. discussed the planar Turán numbers of several double stars and obtained many results. In this paper, we will give the upper bound for the number of edges in the planar graph in which there does not exist a double star
S2,6 and degree sum of adjacent vertices is not equal to 12. That is, if the graph
G is a plane diagram of vertices, and the graph does not contain
S2,6 as a subgraph, and the sum of the degrees of any adjacent two points is not equal to 12, then

.