Detecting hubs and quasi cliques in scale-free networks

Scale-free networks are believed to closely model most real-world networks. An interesting property of such networks is the existence of so-called hub and community structures. In this paper, we model hubs as high-degree nodes and communities as quasi cliques. We propose a new problem formulation called the ¿-list dominating set and show how this single problem is suited to model both the structures in real-world networks better than traditional problems like vertex cover and clique. Additionally, we provide a fixed-parameter tractable algorithm to this detect these structures and show experimental results on protein-protein interaction networks.