FIG. 1.—

Midpoint rooting trees and networks. (a) The pathway from node v_i to v_j and the midpoint (red circle) in a phylogenetic tree is shown. (b) An illustration of the procedure used to root a split network. The two most distant taxa are v_i and v_j. There are two shortest paths between these two taxa (colored arrows) and two midpoints. The numbering of the splits is indicated, noting that the two central splits are associated with two edges each. The vector encoding is made with reference to taxon v_i. The encoding for the root is (1,0,0,0.5,0.5), which corresponds to the center of the central box (red circle).