This happens if the graph is disconnected or has a cutvertex.
如果一个图是不连通的或有割点，就发生这种情况。
2
Finally, for the spectral radius of a graph with a cutvertex, we give an inequality concerning the spectral radius of the graph and its subgraphs.
最后，对于有割点的图的谱半径给出一个与子图的谱半径有关的一个不等式。
3
The algorithm use a binary digit to divide the vertex set of a non-direction graph, and employ the incident sets of the vertices in the subgraph to produce opposite cut sets.