泛圈图的邻域并

摘要

LetNC2 ＝ min｛ ｜N(x) UN(y)｜ ｜x,y ∈ V(G), d(x,y) ＝ 2｜｝ We obtained the following result: if G is a 2 - connected graphs of ordre n with NC2 ≥n -δ, then G is a Pancyclic graph of kn/2, n/2%让NC2 ＝ min｛｜N(x) UN(y)｜｜x,y ∈ V(G), d(x,y) ＝ 2｜｝,得到的主要结果如下：对于2连通n(n≤6)阶图G，如果则G是泛圈图或此结果改进了图论专家R．J．Faudree等的结果．