Contemporary science has been particularly successful in addressing the physical properties of systems that are composed of many identical elements interacting through mainly local interactions. For example, many successes of materials science and solid state physics are based on the fact that most solids are made of relatively few types of elements that exhibit spatial order by forming a crystal lattice. Furthermore, these elements are coupled by local, nearest-neighbor interactions. However, the inability of contemporary science to describe systems composed of non-identical elements that have diverse and non-local interactions currently limits advances in many disciplines, ranging from molecular biology to computer science [1,2]. The diculty in describing these systems lies partly in their topology: many of them form complex networks, whose vertices are the elements of the system and edges represent the interactions between them.