Figure 6

Illustrating proof that cycles formed by completeBundle can contain only zero or one TT adjacency. g _h l is the cuttable edge formed when kl is destroyed as k is incorporated into a cycle. Case A reflects the first step in Figure 5 (r > 1), not involving any TT adjacencies. Cases B and C show how the paths from an originally closed bundle enter into the completion process thanks to the switched adjacency of a pair of half paths illustrated in Figure 3. Case D shows how two (or more) such adjacencies can accumulate in one path, but always with a cuttable edge between them. Cases E and F show how a single adjacency is incorporated in a cycle, through deletion of the cuttable edge between the adjacency and any other adjacency in the path. Cases G and H show a step in the completion of an open bundle without T, constructed as in Figure 4, also leading to the entry of originally closed bundle paths into the completion process.