The red nodes in Figure 3(b) indicate the nodes in the set V ' (STEP-1), similar red colored edges indicate the edges in E '. After list ranking (STEP-3) we will have four maximal chains as follows, . Now if we stick to the convention described in STEP-5 we renumber the new node corresponding to the chains as Y
. As a result the edges and are updated (shown in green in Figure 3(c)) as and Finally the directed edges are replaced with bi-directed edges in Figure 3(d).