关于顶点子集凝聚度的若干定理(续)

本文引进斥负集点、斥零集点新概念．并利用这些概念研究出顶点子集X 是只有形如NG（ｖ）最小断集的图G的负集的充要条件是：1°X 包含图G中所有度等于K(G)的顶点；2°图G不包含关于X的斥负集点；3°NG(X)中的任意点U， ，K 表示U与X相邻的顶点数，同时指出Y是图G的非特殊零集的充要条件．

Several Theorems of Cohesiveness of Subset of Points(Continuation)

The point or excluded negative set and the point of excluded zero set are intro- duced in this paper. These new concepts are find to find out the necessary and sufficient con- ditions for the subset or points X to be the negative set of graph G with only its form like the smallest disconnecting set or NG(V). the conditions are: (1) X includes all the points with de- grees equal to K(G) in graph G. (2) Points of excluded negative set about X are not included in graph G. (3) For an arbitrary point u in NG(X), dG(u) > K(G) + k, 1 < k < |X|, k indi- cates the number or points which u and x are neighbouring. Meanwhile, the sufficient condi- tions for X to be the nonspecial zero set or graph G are found out also.