Fig. 2

The network structures of the four simulated networks. The structure of the real protein-protein interaction networks [47] were used to construct networks of different sizes by varying the number of references required to support each connection. In the degree distribution, the 0.95 quantile is 7 (connections), so the nodes with more than 7 connections were defined as hub nodes, which are represented as black nodes in the network structure. a 52 edges among 44 nodes (3 hubs), b 103 edges among 83 nodes (3 hubs), c 290 edges among 231 nodes (8 hubs) and d 837 edges among 612 nodes (33 hubs)