Figure 7: Degree distributions for different networks. The horizontal axis is node degree (or ), and the vertical axis is the probability distribution (or ) of degrees, that is, the fraction of nodes that have degree greater than or equal to . The network shown in (a) is a heterogeneous network with two types of nodes, three networks (of power law, heterogeneous, and Poisson distribution) are depicted in (b) with a logarithmic degree scale.