选一个“特定”的点 all intemediate vertices in2....-1 all intermediate vertices in....-1 p:all intermediate vertices in12..... Figure 25.3 Path p is a shortest path from vertex i to vertex,and k is the highest-numbered intermediate vertex of p.Path p.the portion of path p fromvertex i to vertexk,has all intermediate vertices in the set(12....-1).The same holds for path p2 from vertexk to vertexj.选一个“特定”的k点