Fig. 2

In this figure, two example PPI networks are given. Green nodes are proteins which are in the same pathway (i.e., a pathway with the same number in both species). Dotted lines represent the alignment π between these two networks. Under this alignment, there are five conserved interactions between proteins in this pathway (shown by thick black edges in each network). Also, the number of correctly mapped proteins is four. Therefore, the accuracy of aligning this pathway is \(acc_{\pi,i} = \frac {2 \times 4}{6 + 5}\), where there are six and five proteins from this pathway in each species, respectively