没有完美匹配的二部图G,若给它任意增加一条新的边,结果得到的二部图有完美匹配,则称图G是饱和的.设X包含于V(G),Γ(X)表示V(G)中与X中至少一个顶点相邻的所有顶点组成的集合.本文证明了一个二部图G=(U,W)是饱和的当且仅当(a)存在唯一X包含于U,使得X〉Γ(X),X-1〉Γ(X)且G的导出子图G[X∪Γ(X)]是完全二部图;(b)G的导出子图G[(U-X)∪(W-Γ(X))]是完全二部图,且满足U-X+1=W-Γ(X);(c)U-X中每个顶点与W中的每个顶点都相邻,且X∪(W-Γ(X))是图G的一个独立集.
A bipartite graph G without a perfect matching is said to be saturated if any new line is added,the resulting bipartitegraph having a perfect matching. For Xlohtai in V(G),Γ(X)denotes all points in V(G)which are adjacent to at least one point of X. It isobtained that a bipartite graph G=(U,W)is saturated if and only if (a)there is only one Xlohtai in U such that X Γ(X) with X -1=Γ(X) and the induced subgraph G[X∪Γ(X)]is a complete bipartite graph;(b)G[(U-X)∪(W-Γ(X))]with U-X +1= W-Γ(X)is a complete bipartite graph;(c)every point of U-X is adjacent to every point of W and X∪(W-Γ(X))is an independent set.