To simplify our arguments, as shown in Figure 2 below, we assume that v and y are the same vertex and u and x are connected by one edge in the tree . Let a denote the edge ux. Now, we look at the subtree TR in R and consider the cut (R1, R2) formed when a is removed from TR. Let R1 and R2 contain u and x, respectively. Figure 2. A Special Case Let us check our understanding of the notation. Recall that T is an MST of 9 and we remove edge b from T. When we apply Strategy A, we add the edge c. In the following diagram, identify the vertices u v, x and the edge a. Then indicate the sets R1, R2 and S. N . . .. .... N N N . .. ..... - -. .......... . . . . . ...... N N V 4 N is connected by some path in the