电子商务中的一种潜在信任关系预测方法

信任关系在用户寻找可靠信息方面扮演了重要角色。已有信任关系预测方法主要基于信任的传递性和用户间的相似度。然而,在电子商务应用中,不同声誉度的用户对于商品的评价会对其他用户的购买行为产生不同的影响,用户声誉度的差异性会在较大程度上影响用户间建立信任关系的可能性。因此,针对电子商务应用,给出了用户信任关系子网络和用户商品评价关系子网络的形式化描述。根据社会学理论,提出了一种基于用户相似度和全局声誉度的潜在信任关系预测方法,旨在挖掘电子商务应用中陌生用户间潜在的信任与不信任关系,为用户辨别评价信息的可信性,进而选择可信商品提供辅助决策。基于Epinions数据集的对比实验结果表明,该方法在信任关系预测的准确度方面有较好的表现。     

一种基于改进D-S证据理论的信任关系强度评估方法研究

随着Web 2.0技术的迅速发展,社会网络开始在我们的生活中扮演着重要的角色,越来越多的人在网络中发表言论、互相交流、共享信息.然而,在社会网络中,信任关系是用户间进行交互的基础,不同用户之间的信任关系强度不同,相同用户在不同领域内的信任关系强度也存在差异,信任关系的不确定性是信任评估的最大挑战.针对以上问题提出了一种基于改进D-S证据理论的灵活直观的评估方法,该方法综合考虑用户被关注度、用户信誉度、用户活跃度和用户相似度4个方面,将这4个方面作为4个属性证据,同时根据模糊理论中的隶属度原理获取基本信任分配,然后基于以上4个属性证据构建多源属性证据信任关系强度融合模型,在领域内对其信任关系强度进行评估,最后采用Epinions中真实的数据集进行实验.实验结果验证了该方法的可行性和优势,为复杂的社会网络环境中信任关系强度评估的研究提供了有价值的新思路.     

复杂网络环境下基于信任传递的推荐模型研究

针对推荐系统中普遍存在的数据稀疏和冷启动等问题,本文结合用户自身评分与用户的社会信任关系构建推荐模型,提出了一种基于信任关系传递的社会网络推荐算法（Trust transition recommendation model,TTRM）.该方法首先通过计算信任网络中节点的声望值与偏见值来发现信任网络中的不可信节点,并通过对其评分权重进行弱化来减轻其对信任网络产生的负面影响.其次,算法又利用朋友的信任矩阵对用户自身的特征向量进行修正,解决了用户特征向量的精准构建及信任传递问题.同时为了实现修正误差的最小化,算法利用推荐特性进行用户相似度计算并通过带有社会正则化约束的矩阵分解技术实现社会网络推荐.实验结果表明,TTRM算法较传统的社会网络推荐算法在性能上具有显著提高.     

融合双重正则化机制的低秩矩阵分解推荐模型

基于矩阵分解技术的社会化推荐通过加入用户信任关系来加强学习准确性,但忽略了物品之间的关联信息在模型分解过程中对用户兴趣的影响。对此首先提出在物品相似度计算方法中加入用户参与度进行改进,并构建了融合物品关联正则项和信任用户正则项双重约束的矩阵分解推荐模型,在优化隐式特征矩阵过程中体现了物品之间的关联信息对推荐的重要影响。最后通过对两个不同稀疏级别的数据集的实验证明,相比主流的矩阵分解模型,提出的双重正则项的矩阵分解模型能够提高稀疏数据集上预测评分的准确性,并能明显缓解用户冷启动问题。     

基于用户评论的信任预测方法研究

在线社会网络中,信任关系是用户间进行可靠交互的基础,交互的强度也会影响用户间信任关系的建立。虽然许多研究者对信任建模及其预测进行了研究,但大部分的研究都是基于已有网络进行的,缺乏对用户交互行为及内容的深入研究。在这种情况下,针对原有网络的稀疏性问题和用户交互行为对信任关系的影响进行了研究,提出了一种基于信任网络和用户评分行为的信任预测框架。该框架给出了一种评估用户间交互关系强弱的度量机制,结合用户间已建立的信任关系网络,综合评估预测用户间的信任与不信任关系。基于Epinions网站的真实数据集进行了多组实验,实验表明用户交互行为对信任的度量有着重要的影响,综合考虑这两方面可以更准确地对信任关系做出预测。     

一种基于社会信任潜在因子模型的推荐方法

随着社交网络的快速发展、社交网络用户规模的不断扩大,如何为用户推荐感兴趣的信息变得越发困难。传统的推荐方法利用用户兴趣的历史数据来预测用户未来感兴趣的项目,忽视了社交网络中的信任关系,导致推荐方法的推荐质量不高。针对上述问题,提出了基于社会信任潜在因子模型的推荐方法。该方法引入社会信任来度量社交网络中朋友之间的隐含信任关系,根据社会信任程度来选择用户信任的朋友,对用户信任的朋友与目标用户的共同兴趣进行潜在因子分析,构建基于社会信任的潜在因子模型,实现目标用户的前k个项目推荐。真实数据集上的对比实验结果表明,基于社会信任潜在因子模型的推荐方法在推荐质量上优于现有的推荐方法。     

基于链路预测的微博用户关系分析

随着以微博为代表的在线社交网站的发展,微博用户之间形成了复杂的社会网络。针对微博社会网络,研究了影响微博用户之间关系形成的各种因素,提出了基于链路预测的微博用户关系分析模型。首先分析了网络结构特征在微博社会网络中的作用,同时针对微博社会网络的特点,引入微博属性特征,构造基于随机森林的链路预测模型,并将模型应用于新浪微博用户数据集,进行微博用户关系的训练预测,通过比较引入微博属性特征前后的预测性能以及特征的重要性分布,分析了各类特征对微博用户关系形成的影响,揭示了除传统的网络结构特征外,微博属性特征对微博用户关系的形成具有重要的影响力。     

结合用户组群和隐性信任的概率矩阵分解推荐

研究表明在社会网络推荐中添加明确的社会信任明显提高了评分的预测精度,但现实生活中很难得到用户之间明确的信任评分。之前已有学者研究并提出了信任度量方法来计算和预测用户之间的相互作用及信任评分。提出了一种基于Hellinger距离的社会信任关系提取方法,通过描述二分网络中一侧节点的f散度来进行用户相似度计算。然后结合用户分组信息,将提取的隐式社会关系加入改进的概率矩阵分解中,提出一种新的基于用户组群和隐性社会关系的概率矩阵分解算法（CH-PMF）。实验结果表明,提出的模型与应用实际用户明确表示的信任分数推荐结果表现几乎相同,且在无法提取到明确信任数据时,CH-PMF有着比其他传统算法更好的推荐效果。     

基于概率的信任传播模型

社会网络中,用户之间的信任关系可以为用户判别信息是否可信提供依据。现有的信任计算方法一般是通过搜索节点之间的路径,再在其上添加各种其它限制,如路径长度、信任度下界等来计算信任度,而考虑节点之间的相似性的方法却很少。从节点之间的相似性出发,在信任传播模型的基础上,结合贝叶斯条件概率公式,提出了基于概率的信任传播模型。同时分析了信任传播模型中衰减系数对结果的影响;通过统计分析数据,得出具有信任关系的用户之间的相似度要比不具有信任关系的用户之间的相似度高得多,从而证明了贝叶斯理论可显著提高信任传播算法的有效性。在Epinion数据集上进行的实验证明了该方法的有效性。     

用于社交推荐的增强影响扩散模型

随着网络上创建连接、协作、共享的全新变革方式的出现,互联网上丰富的社交行为现象引起了研究者和实践者的关注.近年来,随着社交网络平台的普及与推广,基于社交网络的推荐系统也成为了个性化推荐领域的研究热点之一,社交推荐系统可以利用社交网络来缓解传统的推荐算法中数据稀疏性问题.在社交网络中,社交关系影响起着重要作用,而用户信任是社交关系形成的基础,每一个用户会受到其信任的用户影响,这些被信任的用户也会被自己的社交关系所影响,这就表明了联系在一起的用户会相互影响,导致社交联系之间的用户偏好具有相似性.用户的信任关系影响着用户偏好的推断,同时用户受到其信任用户的社交关系影响,而这些社交关系影响在社交网络中递归传播和扩散.因此,基于社交推荐算法研究的关键就在于信任信息的挖掘和利用.在基于社交网络的推荐领域中,比较有代表性的模型为Diff Net,该模型未充分考虑到信任问题,同时,在递归计算长距离的社交关系时,有额外的噪声,影响推荐预测的质量.本文提出了基于Diff Net改进的社交推荐模型-EIDNet.首先,该模型在模拟社交关系影响扩散过程时,通过用户对物品的历史交互记录建立用户间的信任关系,并融...     

Building trust networks in the absence of trust relations

User-specified trust relations are often very sparse and dynamic, making them difficult to accurately predict from online social media. In addition, trust relations are usually unavailable for most social media platforms. These issues pose a great challenge for predicting trust relations and further building trust networks. In this study, we investigate whether we can predict trust relations via a sparse learning model, and propose to build a trust network without trust relations using only pervasively available interaction data and homophily effect in an online world. In particular, we analyze the reliability of predicting trust relations by interaction behaviors, and provide a principled way to mathematically incorporate interaction behaviors and homophily effect in a novel framework, bTrust. Results of experiments on real-world datasets from Epinions and Ciao demonstrated the effectiveness of the proposed framework. Further experiments were conducted to understand the importance of interaction behaviorsand homophily effect in building trust networks.     

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。     

Node trust evaluation in mobile ad hoc networks based on multi-dimensional fuzzy and Markov SCGM(1, 1) model

Due to the nature of distribution and self-organization, mobile ad hoc networks rely on cooperation between nodes to transfer information. One of the key factors to ensure high communication quality is an efficient assessment scheme for risks and trust of choosing next potential cooperative nodes. Trust model, an abstract psychological cognitive process, is one of the most complex concepts in social relationships, involving factors such as assumptions, expectations and behaviors. All of the above make it difficult to quantify and forecast trust accurately. In this paper, based on the theories of fuzzy recognition with feedback, SCGM(1, 1) model and Markov chain, we present a pattern of prediction making. The analysis and experimental computation show that this scheme is efficient in trust prediction for ad hoc networks.     

基于行为监控的自适应动态信任度测模型

大规模分布式系统中的动态信任关系模型本质上是最复杂的社会关系之一,涉及假设、期望、行为和环境等多种因子,很难准确的定量表示和预测.将粗糙集理论和信息熵理论结合起来,应用于开放环境下动态构建基于行为数据监控与分析的信任关系度测(度量与预测)模型.该方法直接从分析传感器监测到的动态数据入手,针对影响信任的多个度测指标进行自适应的数据挖掘与知识发现,从而改变了传统的信任关系建模思路,跳出了传统信任关系建模过程中各种主观假设的束缚,并克服了传统模型对多维数据处理能力不足的问题.实验结果表明,与已有模型相比,新模型能够快速准确地实现开放分布式环境下实体的可信性判别,而且具有良好的行为数据规模的扩展能力.     

一种基于半环理论的可信性评估模型

在网络安全领域,可信指的是参加各种协议的各个实体之间关系的集合,这些关系是建立在实体在某个协议之上进行相互操作的行为之上的,为了加强网络的安全性,评估结点的可信性是非常重要的。讨论了对可信事件的评估：首先介绍了可信的相关概念和相关的特性;接着评估过程被建模成一个在有向图寻找最短路径的问题,在该有向图中结点表示实体或者用户,边表示可信关系,通过使用半环理论,建立了一个基于半环的可信性评估模型TD-SEMIRING,在两个以前没有进行相互操作的实体之间建立间接的可信关系,介绍了这个模型在路由选择当中的应用;最后,通过仿真实验,验证、分析了该模型的有效性。     

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.     

FlowTrust: trust inference with network flows

Web-based social networking is increasingly gaining popularity due to the rapid development of computer networking technologies. However, social networking applications still cannot obtain a wider acceptance by many users due to some unresolved issues, such as trust, security, and privacy. In social networks, trust is mainly studied whether a remote user behaves as expected by an interested user via other users, who are respectively named trustee, trustor, and recommenders. A trust graph consists of a trustor, a trustee, some recommenders, and the trust relationships between them. In this paper, we propose a novel FlowTrust approach to model a trust graph with network flows, and evaluate the maximum amount of trust that can flow through a trust graph using network flow theory. FlowTrust supports multi-dimensional trust. We use trust value and confidence level as two trust factors.We deduce four trust metrics from these two trust factors, which are maximum flow of trust value, maximum flow of confidence level, minimum cost of uncertainty with maximum flow of trust, and minimum cost of mistrust with maximum flow of confidence. We also propose three FlowTrust algorithms to normalize these four trust metrics. We compare our proposed FlowTrust approach with the existing RelTrust and CircuitTrust approaches. We show that all three approaches are comparable in terms of the inferred trust values. Therefore, FlowTrust is the best of the three since it also supports multi-dimensional trust.     

Socialized healthcare service recommendation using deep learning

Socialized recommender system recommends reliable healthcare services for users. Ratings are predicted on the healthcare services by merging recommendations given by users who has social relations with the active users. However, existing works did not consider the influence of distrust between users. They recommend items only based on the trust relations between users. We therefore propose a novel deep learning-based socialized healthcare service recommender model, which recommends healthcare services with recommendations given by recommenders with both trust relations and distrust relations with the active users. The influences of recommenders, considering both the node information and the structure information, are merged via the deep learning model. Experimental results show that the proposed model outperforms the existing works on prediction accuracy and prediction coverage simultaneously, even for cold start users or users with very sparse trust relations. It is also computational less expensive.

     

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.     

信任传播与信任关系发现方法

信任管理是一种具有动态可扩展性的新型访问控制方法.在现有信任管理研究成果的基础上,参照人类社会基于信任的交互机制,提出了一种基于信任度的访问控制模型,并对其中的信任传播与信任关系发现进行了重点研究.参照人类社会的信任传播模式,并基于自组织理论,提出了一种信任自主传播模型,实现信任动态、广泛的传播.通过引入计算机网络中分...