【摘要】 如果6连通图的一条边收缩后使得所得到的图仍是6连通,则这条边称为6可收缩边.一个不包含6可收缩边的非完全图被称为收缩临界6连通图.由Egawa的结果可知:收缩临界6连通图中有6度点.设G是收缩临界6连通图,用V6表示G中6度点的集合.Ando等人通过证明存在常数c使得|V6|>c|V(G)|且c≥17.现将这一常数改进为c≥15.更多还原

【Abstract】 An edge of a 6 connected graph is said to be 6-contractible if its contraction results still in a 6 connected graph.A noncomplete 6 connected graph is called contraction-critical if it has no any 6-contractible edge.Let G be a contraction-critical 6 connected graph.By Egawa’s result,G has a vertex of degree 6.Let V₆ denote the set of vertices of degree 6 in G.Recently,Ando et.al showed that there is a constant c such that ｜V₆｜≥c｜V（G）｜,and c≥17.In this note,it is proved that c≥15.更多还原