An important class of graph data is the social data, generated from online social networks (OSNs). The social data have been growing rapidly over the internet through various OSNs, including online websites (such as Facebook, LinkedIn, and ResearchGate) and messengers (such as Skype). The widespread use of them leads to an increasing interest in efficiently and correctly discovering important, useful, and implicit information. Efficient techniques for data harnessing about social data are crucial to applications across many domains, including public safety, environment management, election, and viral marketing.