间题6： 两个biock的“边界”是什么？ Corollary 5.9 Every two distinct blocks Bi and B2 in a nontrivial connected graph G have the following properties: (a)The blocks B and B2 are edge-disjoint. (b)The blocks B and B2 have at most one vertex in common. (c)If Bi and B2 have a vertex v in common,then v is a cut- vertex of G
Corollary 5.9 Every two distinct blocks 𝐵1 and 𝐵2 in a nontrivial connected graph 𝐺 have the following properties: (a) The blocks 𝐵1 and 𝐵2 are edge-disjoint. (b) The blocks 𝐵1 and 𝐵2 have at most one vertex in common. (c) If 𝐵1 and 𝐵2 have a vertex 𝑣 in common, then 𝑣 is a cutvertex of 𝐺
点连通度K(G) 最小点割集的势 请特别注意：极小点割集和最小点割集 minimala和minimum
点连通度𝜅(𝐺) 请特别注意：极小点割集和最小点割集 minimal和minimum 最小点割集的势
K-连通图 K(G)≥k 间题7： 从一个k-连通图中删除k个点，剩下的图是否一 定不连通了？ 注意： G =K for some positive integer n,then x(G)is defined to be n -1. 问题8 Blocki和2-连通图是什么关系？Bock的连通度？
K-连通图 从一个k-连通图中删除k个点，剩下的图是否一 定不连通了？ 𝜅 𝐺 ≥ 𝑘 注意： 𝐺 = 𝐾𝑛 for some positive integer 𝑛, then 𝜅(𝐺) is defined to be 𝑛 − 1
问题9： 边连通度是什么概念？ 我们能够简称4边连通度图为4连通图吗？
边连通度λ(G) 最小边割集的势 An edge-cut in a nontrivial graph G is a subset X of edges of G such that G -X is disconnected. An edge-cut X of a connected graph G is minimal if no proper subset of X is an edge-cut of G. An edge-cut of minimum cardinality is called a minimum edge-cut
边连通度𝜆(𝐺) 最小边割集的势 An edge-cut of minimum cardinality is called a minimum edge-cut. An edge-cut in a nontrivial graph 𝐺 is a subset 𝑋 of edges of 𝐺 such that 𝐺 − 𝑋 is disconnected. An edge-cut 𝑋 of a connected graph 𝐺 is minimal if no proper subset of 𝑋 is an edge-cut of 𝐺