Nearest close friend search in geo-social networks

In this paper, we define a novel type of geo-social query called the k-Nearest ℓ-Close Friends query, which retrieves the k nearest data objects from among the ℓ-hop friends of the query user. We also propose three approaches for processing a kℓ-NCF query: Neighboring Cell Search, Friend-Cell Search, and Personal-Cell Search. In addition, we develop an efficient method of index update for supporting dynamic environments. We conduct a variety of experiments on synthetic and real data sets to evaluate and compare our methods.