设G是有限简单无向图,使G-S的每个分支都不含孤立的边割S称为G的限制边割。G的限制连连通度λ’(G)是G的限制边割之中最少的边数,定义ξ(G)=min|d(x)+d(y)-2;xy∈E(G)}为G的最小边度。如果λ’(G)=ξ(G),则称G是λ'最优的。若任意最小限制边割都弧立一边,则称图G是超级λ’的。应用范型度条件给出了图是λ’最优和超级λ’的令分条件。
Let G be a finite, simple and undirected graph. An edge-cut S of G is called a restricted edge-cut if G-S contains no isolated vertices. The minimum cardinality of all restrictededge-cuts is called the restricted connectivity of G,denoted by λ'(G). Let ξ(G) = min{ d(x) + d(y) - 2: xy ∈ E(G) } be the minimum edge-degree of G. We call G λ'-optimal if λ'(G) =6(G) and super-λ' if every minimum restricted edge-cut isolates an egeg. This paper shouws. Sufficient conditions for graphs to be λ'-optimal and super-λ' are shoun by Fan-type condition