Many networks of interest in the science, including social networks, computer networks and the World Wide Web, are found to be divided naturally into communities or groups. The problem of detecting communities is one of the outstanding issues in the study of network systems. Based on the...

Humans often behave discriminatorily towards others depending on their group membership. In this work, we establish a spatial Prisoner’s dilemma model to investigate the relation between tag-mediated discrimination and cooperation. By introducing tag-mediated selective interaction, we find...

We investigate the topological properties of N(N⩾1) disclination lines in cholesteric liquid crystals. The topological structure of N disclination lines is obtained with the Hopf index and Brouwer degree. Furthermore, the knotted χ disclination loops is proposed with the Hopf invariant. And...