  We study a subset of the movie collaboration network, imdb.com, where only
adult movies are included. We show that there are many benefits in using such a
network, which can serve as a prototype for studying social interactions. We
find that the strength of links, i.e., how many times two actors have
collaborated with each other, is an important factor that can significantly
influence the network topology. We see that when we link all actors in the same
movie with each other, the network becomes small-world, lacking a proper
modular structure. On the other hand, by imposing a threshold on the minimum
number of links two actors should have to be in our studied subset, the network
topology becomes naturally fractal. This occurs due to a large number of
meaningless links, namely, links connecting actors that did not actually
interact. We focus our analysis on the fractal and modular properties of this
resulting network, and show that the renormalization group analysis can
characterize the self-similar structure of these networks.
