基于社会学理论的信任关系预测模型

随着社会网络的盛行,信任作为用户之间交互的基础,在信息共享、经验交流和社会舆论方面发挥着重要作用。然而,信任是一个复杂而抽象的概念,受多种因素影响,很难识别信任形成的诱因以及其形成机制。由于来自社会科学的社会学理论有助于解释社会现象,而社会网络反映了现实世界中用户之间的联系,因此,从社会学角度出发,通过研究社会等级理论和同质性理论获取信任关系的发展规律,进而构建信任关系预测模型。首先,对社会等级理论和同质性理论进行阐述,并验证了社会等级理论和同质性理论在社会网络中的存在;然后,分别针对社会等级理论和同质性理论对信任关系的影响提出社会等级正则化方法和同质性正则化方法;最后,利用非负矩阵的三维分解方法并结合社会等级理论和同质性理论实现对信任关系预测的建模,并提出 SocialTrust 模型用于信任关系预测。实验结果表明,相比于其他方法,该方法在信任关系预测方面具有较高的精度。     

Modeling online user behaviors with competitive interactions

Online user behaviors are increasingly modulated by social media. Extant literature mainly focuses on investigating how network structures affect user behaviors. However, recent empirical results demonstrate that user behaviors and network structures usually coevolve dynamically, and topological patterns turn out to be inadequate for characterizing real-world user behaviors. In this paper, we present a dynamic model to deal with this challenge. This proposed model is mainly governed by two competing principles: homophily and homeostasis. Empirical evaluations of three online real-world datasets suggest that the proposed dynamic model can well predict long-range online user behaviors.     

Strategies for predicting local trust based on trust propagation in social networks

Trust plays a critical role in determining social interactions in both online and offline networks, and reduces information overload, uncertainties and risk from unreliable users. In a social network, even if two users are not directly connected, one user can still trust the other user if there exists at least one path between the two users through friendship networks. This is the result of trust propagation based on the transitivity property of trust, which is “A trusts B and B trusts C, so A will trust C”. It is important to provide a trust inference model to find reliable trust paths from a source user to an unknown target user, and to systematically combine multiple trust paths leading to a target user. We propose strategies for estimating level of trust based on Reinforcement Learning, which is particularly well suited to predict a long-term goal (i.e. indirect trust value on long-distance user) with short-term reward (i.e. direct trust value between directly connected users). In other words, we compare and evaluate how the length of available trust paths and aggregation methods affects prediction accuracy and then propose the best strategy to maximize the prediction accuracy.     

Context-aware trust network extraction in large-scale trust-oriented social networks

In recent years, social networking sites have been used as a means for a rich variety of activities, such as movie recommendations and product recommendations. In order to evaluate the trust between a truster (i.e., the source) and a trustee (i.e., the target) who have no direct interaction in Online Social Networks (OSNs), the trust network between them that contains important intermediate participants, the trust relations between the participants, and the social context, has an important influence on trust evaluation. Thus, to deliver a reasonable trust evaluation result, before performing any trust evaluation (i.e., trust transitivity), the contextual trust network from a given source to a given target needs to be first extracted from the social network, where constraints on social context should also be considered to guarantee the quality of the extracted networks. However, this problem has been proved to be NP-Complete. Towards solving this challenging problem, we first present a contextual trust-oriented social network structure which takes social contextual impact factors, including trust, social intimacy degree, community impact factor, preference similarity and residential location distance into account. These factors have significant influences on both social interactions between participants and trust evaluation. Then, we present a new concept QoTN (Quality of Trust Network) and propose a social context-aware trust network extraction model. Finally, we propose a Heuristic Social Context-Aware trust Network extraction algorithm (H-SCAN-K) by extending the K-Best-First Search (KBFS) method with several proposed optimization strategies. The experiments conducted on two real datasets illustrate that our proposed model and algorithm outperform the existing methods in both algorithm efficiency and the quality of the extracted trust networks.     

Improved trust-aware recommender system using small-worldness of trust networks

The trust network is a social network where nodes are inter-linked by their trust relations. It has been widely used in various applications, however, little is known about its structure due to its highly dynamic nature. Based on five trust networks obtained from the real online sites, we contribute to verify that the trust network is the small-world network: the nodes are highly clustered, while the distance between two randomly selected nodes is short. This has considerable implications on using the trust network in the trust-aware applications. We choose the trust-aware recommender system as an example of such applications and demonstrate its advantages by making use of our verified small-world nature of the trust network.     

Exploiting two-faceted web of trust for enhanced-quality recommendations

Traditional collaborative filtering (CF) based recommender systems on the basis of user similarity often suffer from low accuracy because of the difficulty in finding similar users. Incorporating trust network into CF-based recommender system is an attractive approach to resolve the neighbor selection problem. Most existing trust-based CF methods assume that underlying relationships (whether inferred or pre-existing) can be described and reasoned in a web of trust. However, in online sharing communities or e-commerce sites, a web of trust is not always available and is typically sparse. The limited and sparse web of trust strongly affects the quality of recommendation. In this paper, we propose a novel method that establishes and exploits a two-faceted web of trust on the basis of users’ personal activities and relationship networks in online sharing communities or e-commerce sites, to provide enhanced-quality recommendations. The developed web of trust consists of interest similarity graphs and directed trust graphs and mitigates the sparsity of web of trust. Moreover, the proposed method captures the temporal nature of trust and interest by dynamically updating the two-faceted web of trust. Furthermore, this method adapts to the differences in user rating scales by using a modified Resnick’s prediction formula. As enabled by the Pareto principle and graph theory, new users highly benefit from the aggregated global interest similarity (popularity) in interest similarity graph and the global trust (reputation) in the directed trust graph. The experiments on two datasets with different sparsity levels (i.e., Jester and MovieLens datasets) show that the proposed approach can significantly improve the predictive accuracy and decision-support accuracy of the trust-based CF recommender system.     

Building trust online: Interactions among trust building mechanisms

Lack of trust has been shown to be a major obstacle to the adoption of online shopping. However, there has been little investigation of the effectiveness of various trust building mechanisms and their interactions. In our study, three trust building mechanisms (third-party certification, reputation, and return policy), were examined. A scenario survey method was used for data collection. 463 usable questionnaires were collected from respondents with diverse backgrounds. Regression results showed that all three trust building mechanisms had significant positive effect on trust of the online vendor. However, their effects were not simple; they interacted to produce a different overall effect on the level of trust. These results have both theoretical and practical implications.     

Online social trust reinforced personalized recommendation

Recommendation techniques greatly promote the development of online service in the interconnection environment. Personalized recommendation has attracted researchers’ special attention because it is more targeted to individual tasks with the characteristics of diversification and novelty. However, the data sets that personalized recommendation process usually possess the characteristics of data sparseness and information loss, which is more likely to have problems such as cognitive deviation and interest drift. To solve these issues, in recent years people gradually notice the important role in which trust factor plays in promoting the development of personalized recommendation. Given the difference between online social trust and traditional offline social trust in facilitating personalized recommendation, this paper proposes a novel technique of online social trust reinforced personal recommendation to improve the recommendation performance. Compared with traditional offline social trust-based personal recommendation, our work synthesizes both factors of online social trust and offline social trust to identify private and public trusted user communities. The trusted degree or the accredited degree can be deduced by Bayesian network probabilistic inferences. In this way, the performance of personalized recommendation can be improved by avoiding excessive interest deviation. Moreover, we also get time sequence into personal recommendation model to effectively track how user’s interest changes over time. Accordingly, the recommendation accuracy can be improved by eliminating the unfavorable effect of interest drift caused by temporal variation. Empirical experiments on typical Yelp testing data set illustrate the effectiveness of the proposed recommendation technique.     

Social media and relationship development: The effect of valence and intimacy of posts

Social media is becoming an increasingly common part of everyday life. Many social media sites (e.g. Facebook, Twitter and LinkedIn) support new interpersonal interaction methods, some of which are neither directed nor reciprocated. For example, social media users can read online 'posts' (self-disclosures) of their friends without interacting with those friends. This is vastly different to traditional face-to-face communication. Our study investigated how reading online 'posts' affects relationship development. Using a longitudinal design sampling 243 participants, we focused on the effect of the posts' valence and intimacy. We found that high intimacy posts or negative posts decreased the social attractiveness of the self-discloser. The perception of the posts and the receiver's feelings of homophily to the self-discloser mediated this relationship. Studies of offline interpersonal interaction have found similar results. In offline communication, self-disclosure perception and homophily also mediate relationship outcomes. This suggests that reading posts on social media and interacting in real life trigger similar or identical relationship formation pathways. These results support the argument that passive consumption is a new method of interaction that does not fundamentally change human psychology. While novel, passive consumption is still based on the same principles as offline communication.     

Modeling and mining of dynamic trust in complex service-oriented systems

The global scale and distribution of companies have changed the economy and dynamics of businesses. Web-based collaborations and cross-organizational processes typically require dynamic and context-based interactions between people and services. However, finding the right partner to work on joint tasks or to solve emerging problems in such scenarios is challenging due to scale and temporary nature of collaborations. Furthermore, actor competencies evolve over time, thus requiring dynamic approaches for their management. Web services and SOA are the ideal technical framework to automate interactions spanning people and services. To support such complex interaction scenarios, we discuss mixed service-oriented systems that are composed of both humans and software services, interacting to perform certain activities. As an example, consider a professional online support community consisting of interactions between human participants and software-based services. We argue that trust between members is essential for successful collaborations. Unlike a security perspective, we focus on the notion of social trust in collaborative networks. We show an interpretative rule-based approach to enable humans and services to establish trust based on interactions and experiences, considering their context and subjective perceptions.     

The influence of disposition and social ties on trust in new virtual teammates

With the increased presence of social media tools such as LinkedIn and Facebook, social network information is now commonplace. Social media websites prominently display the social distance or so-called “degrees of separation” among users, effectively allowing people to view their shared social ties with others, including prospective teammates they have not met. Through the presentation and manipulation of social network information, this longitudinal experiment investigated whether dispositional and relational variables contribute to “swift trust” among new virtual teammates. Data from 74 participants were collected to test a path analytic model predicting that social ties and propensity to trust influence perceptions of a new teammate’s trustworthiness (ability, benevolence, and integrity) as well as the willingness to trust that new teammate when given the opportunity to do so. Path analysis indicated good model fit, but showed no significant evidence that social ties or propensity to trust affect perceived trustworthiness at the initial point of team engagement. Additionally, only one component of perceived trustworthiness (perceived ability) and propensity to trust were found to predict trusting behavior towards a new, unknown, teammate.     

基于迭代回归树模型的跨平台长尾商品购买行为预测

长尾商品是指单种商品销量较低,但是由于种类繁多,形成的累计销售总量较大,能够增加企业盈利空间的商品。在电子商务网站中,用户信息量较少且购买长尾商品数量较少、数据稀疏,因此对用户购买长尾商品的行为预测具有一定的挑战性。该文提出预测用户购买长尾商品的比例,研究单一用户购买长尾商品的整体偏好程度。利用社交媒体网站上海量的文本信息和丰富的用户个人信息,提取用户的个人属性、文本语义、关注关系、活跃时间等多个种类的特征;采用改进的迭代回归树模型MART(Multiple Additive Regression Tree),对用户购买长尾商品的行为进行预测分析;分别选取京东商城和新浪微博作为电子商务网站和社交媒体网站,使用真实数据构建回归预测实验,得到了一些有意义的发现。该文从社交媒体网站抽取用户特征,对于预测用户购买长尾商品的行为给出一个新颖的思路,可以更好地理解用户个性化需求,挖掘长尾市场潜在的经济价值,改进电子商务网站的服务。     

一种基于社会网络的激励兼容的信任模型*

社会网络中的信任关系是最复杂的社会关系之一,涉及多种因素,很难准确量化和预测。综合考虑各种可能因素,在社会网络环境下,构建了一个多维决策信任模型。引入了直接信任,间接信任,风险函数等因子从多个角度描述信任关系的不确定性和复杂性。为抵制恶意实体的不合理行为,提高可信性,加入了一个经济激励机制鼓励交互实体间诚实地合作并激励实体积极参与,最后用密码机制保证激励机制中的安全属性,提高该模型在实际应用中的可信性。     

面向无线自组网的分布式信任管理模型

针对无线自组网的安全问题,提出了一种适用于无线自组网的新的信任管理模型。引入风险值,使模型对恶意行为更加敏感,有利于减少节点行为的突然变化给系统带来的危害。同时,把文件权重因子引入直接信任值计算,有效预防了通过积累信誉实施恶意行为的情况。仿真实验及分析表明,此模型可以有效识别恶意节点,与无信任模型的无线自组网相比,恶意交易的数目明显降低。     

Social network-based service recommendation with trust enhancement

Given the increasing applications of service computing and cloud computing, a large number of Web services are deployed on the Internet, triggering the research of Web service recommendation. Despite of service QoS, the use of user feedback is becoming the current trend in service recommendation. Likewise in traditional recommender systems, sparsity, cold-start and trustworthiness are major issues challenging service recommendation in adopting similarity-based approaches. Meanwhile, with the prevalence of social networks, nowadays people become active in interacting with various computers and users, resulting in a huge volume of data available, such as service information, user-service ratings, interaction logs, and user relationships. Therefore, how to incorporate the trust relationship in social networks with user feedback for service recommendation motivates this work. In this paper, we propose a social network-based service recommendation method with trust enhancement known as RelevantTrustWalker. First, a matrix factorization method is utilized to assess the degree of trust between users in social network. Next, an extended random walk algorithm is proposed to obtain recommendation results. To evaluate the accuracy of the algorithm, experiments on a real-world dataset are conducted and experimental results indicate that the quality of the recommendation and the speed of the method are improved compared with existing algorithms.     

Assessment of subjective influence and trust with an online social network game

The deduction of influence and trust between two individuals only from objective data in online social networks (OSNs) is a rather vague approach. Subjective assessments via surveys produce better results, but are harder to conduct considering the vast amount of friendships of OSN users. This work presents a framework for personalized surveys on relationships in OSNs, which follows a gamification approach. A Facebook game was developed, which was used to subjectively assess social influence and interpersonal trust based on models from psychology. The results show that it is possible to obtain subjective opinions and (limited) objective data about relationships with an OSN game. Also an implicit assessment of influence and trust with subcategory questions is feasible in this case.     

Factors affecting members' trust belief and behaviour intention in virtual communities

In this research we investigate whether antecedent factors of participant trust and institutional trust significantly influence members' trust belief towards virtual communities. Further, we investigate how members' trust levels affect their behaviour intention. A model of factors that affect members' trust in virtual communities is constructed. We analysed 625 valid online questionnaires obtained from virtual communities related to travel, games, and computer information. The findings suggest that benefit attraction and shared value have significant positive effects on building participant trust, and monitoring has a significant positive effect on building institutional trust. Trust building influences both members' stickiness in virtual communities and their willingness to share information. This research suggests that the extent to which members trust community-based website environments significantly influences their practical behaviour in such environments.     

Privacy,trust and control: Which relationships with online self-disclosure?

A number of studies have examined the relationship between privacy concerns, perceived control over information, trust and online self-disclosure, highlighting different points of view to understand this connection. This paper intends to compare these different models of explanation for self-disclosure behaviors in online social networks. Three different hypotheses are verified, using mediation and moderation analyses. The results allow underling the effect of the interaction between privacy concerns and trust on online self-disclosure, along with the absence of a direct influence of privacy concerns on disclosure itself. The results suggest practical implications for online social network providers, most of all with regard to privacy policies in online environments.     

Combining search and trust models in unstructured peer-to-peer networks

Effectiveness of Peer-to-Peer (P2P) systems highly depends on efficiency and scalability of their search algorithms. Moreover, managing trust is a key issue for wide acceptance of P2P computing. Surprisingly, the majority of the available trust systems ignore the underlying search algorithm and assume it is preexisting. We claim that combining search and trust systems yields significant performance gains in terms of network traffic and query success rate. In this paper, we propose a robust and efficient trust based search framework for unstructured P2P networks. Our framework maintains limited size routing indexes combining search and trust data to guide queries to most reputable nodes. By dynamically selecting reputable nodes as score managers, our scheme tracks the reputation of participating peers. In an alternative approach, we aggregate partial reputation values obtained from reverse query paths to introduce a low overhead method for estimating reputation scores of peers. Through P2P network simulation experiments, we find significant performance gains in using our framework.