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The rise of online crowdsourcing services has prompted an evolution from traditional spamming accounts, which spread unwanted advertisements and fraudulent content, into novel spammers that resemble those of normal users. Prior research has mainly focused on machine accounts and spams separately, but characteristics of new types of spammers and spamming make it difficult for traditional methods to perform well. In this paper, we integrate the study of these new types of spammers with the study of crowdturfing microblogs, investigating the mechanism of crowdsourcing and the close relationship between crowdturfing spammers and microblogs in order to detect new types of spammers and spams more precisely. We propose a novel semi-supervised learning framework for co-detecting crowdturfing microblogs and spammers by comprehensively modeling user behavior, message content, and users’ following and retweeting networks. In order to meet the challenge of sparsely labeled datasets, we design an elaborate co-detection target optimal function to minimize empirical error and to permit the dissemination of sparse labels to unlabeled samples. The advantage of this framework is threefold. First, through a deep-level mining of new-type spammers, we aggregate a number of new-found features that can help us make significant distinctions between normal users and new-type spammers. Secondly, by modeling both following networks and retweeting networks, we characterize the essence of the crowdsourcing mechanism abused by spammers in crowdturfing microblog diffusion to markedly increase detection performance. Thirdly, through our optimal function based on semi-supervised methods, we overcome the problem of label sparseness, thus obtaining a more reliable capacity to deal with the challenges of big, sparsely labeled data. Extensive experiments on real datasets demonstrate that our method outperforms four baselines in various metrics (Precision-Recall, AUC values, Precision@K and so on). We also develop a robust system, the functions of which include data collection and availability analysis, spam and spammer detection, and visualization. To render our experiments replicable, we have made our dataset and codes openly available at https://github.com/sunxiangguo/Crowdturfing.

Personality analysis has been widely used in various social services such as mental healthcare, recommendation systems and so on because its natural explainability for AI applications in Web intelligence. With the penetration of Web2.0, traditional social researches have gradually turned to online social networks. However, for a long time, personality detection from online social texts has sunk into an embarrassing situation for the lack of large labeled datasets. Limited by supervised learning frameworks and small labeled datasets, prior works mainly detect one’s personality in the individual perspective, which may not well meet the challenges of massive un-labeled data in the near future. In this paper, we present a first look into group-level personality detection and we use an unsupervised feature learning method instead of supervised methods used in most related works. We propose AdaWalk, a new and novel model of group-level personality detection by learning the influence from text generated networks. The model uses different kernels to evaluate how much a given node should decide its walk path locally or globally. The advantage of AdaWalk is three-folded: a) the model is an unsupervised feature learning method, which means it relies less on annotations. b) by traversing the network, we can capture the influence in the group level, thus the analysis of one’s personality is not only based on individual records but also the information in groups. Therefore, AdaWalk can leverage small datasets more comprehensively. c) AdaWalk is scalable and can be easily transformed as distributed algorithms, which means it has more potential, compared with existing personality detection methods, to meet the massive data without annotations. We use AdaWalk to predict users’ Big Five personality scores in FIVE heterogeneous personality datasets. Compared with more than TEN famous related methods, AdaWalk outperforms the others, meanwhile verifying the significance of the group perspective and unsupervised feature learning methods in the application of personality analysis. To make our experiment repeatable, AdaWalk and related datasets are available at https://xiangguosun.strikingly.com.

Massive knowledge graphs, such as Linked Open Data or Freebase, contain billions of labeled entities and relationships. Star queries aim to identify an entity given a set of related entities, and they are common with massive knowledge graphs. It is important to find the best way to answer star queries, and we can do this by treating it as a graph pattern-matching problem. Because knowledge graphs are noisy and incomplete in nature, we must find answers that match the star pattern closely, and extract a precise match if possible. Thus, here we propose GStar, a framework to identify the top-k best answers for a star query. GStar effectively and efficiently answers top-k star queries on billion-node graphs through a novel query model, an index-free query algorithm, and a distributed query system. We evaluate GStar through experiments on real-world knowledge graphs. Experimental results show that our query model effectively answers real-life star-pattern queries; our query algorithm can answer top-k queries in a near-real-time manner without requiring expensive graph indices; and the distributed system scales well with both the graph size and number of machines used for computation.

Social networking websites with microblogging functionality, such as Twitter or Sina Weibo, have emerged as popular platforms for discovering real-time information on the Web. Like most Internet services, these websites have become the targets of spam campaigns, which contaminate Web contents and damage user experiences. Spam campaigns have become a great threat to social network services. In this paper, we investigate crowd-retweeting spam in Sina Weibo, the counterpart of Twitter in China. We carefully analyze the characteristics of crowd-retweeting spammers in terms of their profile features, social relationships and retweeting behaviors. We find that although these spammers are likely to connect more closely than legitimate users, the underlying social connections of crowd-retweeting campaigns are different from those of other existing spam campaigns because of the unique features of retweets that are spread in a cascade. Based on these findings, we propose retweeting-aware link-based ranking algorithms to infer more suspicious accounts by using identified spammers as seeds. Our evaluation results show that our algorithms are more effective than other link-based strategies.