Set an undirected graph, if there is a subset of vertices, delete G (after deleting the middle vertex and its associated edges), and the number of connected branches of the obtained subgraph satisfies the number of connected branches of G. After deleting any proper subset, it is called the vertex cut set of G, and if there is only one vertex in the vertex cut set, it is called the cut point. If there is a subset of that edge set, ...