Fig. 7.

(L) A cycle in a level-1 network $N^{-}$, and (R) the two simpler networks produced from it by deleting one hybrid edge. The cycle edges in these networks that arise from the original cycle are shown in blue. If $N^{-}$ has a single cycle, then the networks on the right are the two trees in $\mathcal{G}(N^{-})$