Fig. 9

(L) A rooted level-1 network \(N^+\) with 2- and 3-cycles shown in light red, (C) the unrooted topological network \(N^-\) obtained from \(N^+\) by contracting 2- and 3-cycles and undirecting 4-cycles, and (R) a frontier-minimal splits graph that corresponds to \(N^-\) by Theorem 34. Note that the splits graph has a 4-cycle, a 5-dart, and a 6-dart, arising from the 4-, 5-, and 6-cycles of \(N^-\). The metric structure of the splits graph, which is not described by Theorem 34, reflects the split weights as defined by Definition 18. See also Example 37