Community structure in small-world and scale-free networks

The community structure of small-world networks and scale-free networks are explored in the framework of the modularity using computing simulations. We find: first, community structure in small-world networks is clear, but in scale-free networks it is not; second, community structure is affected by the density of the network, namely, the sparser the network connections, the clearer is the community structure; third, modularity in small-world networks is a dynamic variable which changes as a function of the probability of rewiring connections but not monotonically.