围绕割点的若千结论 Theorem 5.1 Let y be a vertex incident with a bridge in a connected graph G.Then v is a cut-vertex of G if and only if degv≥2. Theorem 5.3 Let v be a cut-vertex in a conected graph G and let u and w be vertices in distinct components of G-v. Then v lies on every u-w path in G. Theorem 5.5 Let G be a nontrivial connected graph and let u EV(G).Ifv is a vertex that is farthest from u in G,then v is not a cut-vertex of G.围绕割点的若干结论