Fitch-type solution. The Fitch-type solution applied to the same phylogenetic network and the leaf data in Figure 2. Each vertex is assigned a set of all possible states, along with a score when the network vertices are traversed in post-order. The score at the root gives a upper bound for the optimal score. The state assignments are given during the pre-order traversal phase and the number of substitutions matches with the score at the root.