Personality,User Preferences and Behavior in Recommender systems

This paper reports on a study of 1840 users of the MovieLens recommender system with identified Big-5 personality types. Based on prior literature that suggests that personality type is a stable predictor of user preferences and behavior, we examine factors of user retention and engagement, content preferences, and rating patterns to identify recommender-system related behaviors and preferences that correlate with user personality. We find that personality traits correlate significantly with behaviors and preferences such as newcomer retention, intensity of engagement, activity types, item categories, consumption versus contribution, and rating patterns.     

推荐系统中典型用户群组的发现和应用

推荐系统是解决用户的个性化信息需求的一种有效工具。但随着推荐系统用户规模的扩大,需要合理地从海量用户中筛选出用户子集,并进行持续和深入的分析以改进推荐系统。因此,文中首先提出典型用户群组的概念,以期发现推荐系统中的典型用户子集,从而可正确地反映全体用户的兴趣偏好。随后提出一种典型用户群组的发现算法,通过比较候选新增典型用户对典型用户群组的贡献度,逐一扩大典型用户群组规模,最终达到较高的推荐项目覆盖率和评分准确度。最后在典型用户群组中寻找用户的最近邻,实现一种改进的协同过滤推荐算法。通过在真实数据集上的实验结果表明,与其他用户群组发现算法以及经典推荐算法相比,验证典型用户群组不仅具有较好的代表性,也能够获得更好的推荐效果。     

基于用户树形浏览模式下的推荐系统协同式过滤研究

针对用户普遍使用的树形浏览网页模式,提出一种新的自上而下的用户访问路径收集算法,此算法减少了短路径的生成,并将其合并到用户浏览树形路径中;基于交叉页面访问频度的概念建立交叉页面访问频度矩阵,为推荐系统的协同式过滤核心处理数据源,以交叉页面用户访问比重为判断依据,实现对用户浏览网页关联页面的推荐。     

查询推荐技术综述

本文介绍了用户搜索中查询推荐技术的相关概念、研究现状;深入分析了目前常见的推荐算法及推荐系统中的隐私保护问题;最后,归纳了查询推荐技术的研究热点。     

Improving Social Recommender Systems

Recommender systems play a significant role in reducing information overload for people visiting online sites, but their accuracy could be improved by using data from online social networks and electronic communication tools.     

Explanation in Recommender Systems

There is increasing awareness in recommender systems research of the need to make the recommendation process more transparent to users. Following a brief review of existing approaches to explanation in recommender systems, we focus in this paper on a case-based reasoning (CBR) approach to product recommendation that offers important benefits in terms of the ease with which the recommendation process can be explained and the system’s recommendations can be justified. For example, recommendations based on incomplete queries can be justified on the grounds that the user’s preferences with respect to attributes not mentioned in her query cannot affect the outcome. We also show how the relevance of any question the user is asked can be explained in terms of its ability to discriminate between competing cases, thus giving users a unique insight into the recommendation process.     

Factors Influencing Perceived Benefits and User Satisfaction in Knowledge Management Systems

This study offers a model for predicting users’ perceived benefits and user satisfaction in organizational knowledge management systems. Four constructs are theorized to influence the dependent variables: system quality, knowledge quality, user IS competence, and organizational attitude to knowledge management. The model was empirically tested among 100 respondents working in the knowledge-intensive software industry. The results suggest that knowledge management systems hold certain characteristics to be considered when evaluating technical and socio-psychological factors of users’ perceptions and attitudes toward the systems.     

Recommender Systems for Learning: Building User and Expert Models through Long-Term Observation of Application Use

Information technology has recently become the medium in which much professional office work is performed. This change offers an unprecedented opportunity to observe and record exactly how that work is performed. We describe our observation and logging processes and present an overview of the results of our long-term observations of a number of users of one desktop application. We then present our method of providing individualized instruction to each user by employing a new kind of user model and a new kind of expert model. The user model is based on observing the individual's behavior in a natural environment, while the expert model is based on pooling the knowledge of numerous individuals. Individualized instructional topics are selected by comparing an individual's knowledge to the pooled knowledge of her peers.     

User Satisfaction with Tablet PC Features

Previous studies of tablet personal computers have concentrated on their use in education and healthcare. The current study focused instead on personal usage, investigating how satisfied users are with their own tablets after having used them in their daily lives. The objective was to identify the major features for tablets and to investigate how form factors affect the preference of functions by performing a comparison of iPad1 and Galaxy Tab. Also, gender and ethnicity were analyzed to determine whether they influence satisfaction with the devices. For e‐mail and web browsing functions, users’ ratings showed more satisfaction with the iPad1 since it has a larger display; for the e‐book reader function, users indicated higher satisfaction with the Galaxy Tab. Male users evaluated their devices by the function itself, whereas female users were mainly concerned with aesthetic aspects. Koreans indicated that they were less satisfied with their tablets than were other ethnic groups.     

Providing Justifications in Recommender Systems

Recommender systems are gaining widespread acceptance in e-commerce applications to confront the “information overload” problem. Providing justification to a recommendation gives credibility to a recommender system. Some recommender systems (Amazon.com, etc.) try to explain their recommendations, in an effort to regain customer acceptance and trust. However, their explanations are not sufficient, because they are based solely on rating or navigational data, ignoring the content data. Several systems have proposed the combination of content data with rating data to provide more accurate recommendations, but they cannot provide qualitative justifications. In this paper, we propose a novel approach that attains both accurate and justifiable recommendations. We construct a feature profile for the users to reveal their favorite features. Moreover, we group users into biclusters (i.e., groups of users which exhibit highly correlated ratings on groups of items) to exploit partial matching between the preferences of the target user and each group of users. We have evaluated the quality of our justifications with an objective metric in two real data sets (Reuters and MovieLens), showing the superiority of the proposed method over existing approaches.      

Hybrid Recommender Systems: Survey and Experiments

Recommender systems represent user preferences for the purpose of suggesting items to purchase or examine. They have become fundamental applications in electronic commerce and information access, providing suggestions that effectively prune large information spaces so that users are directed toward those items that best meet their needs and preferences. A variety of techniques have been proposed for performing recommendation, including content-based, collaborative, knowledge-based and other techniques. To improve performance, these methods have sometimes been combined in hybrid recommenders. This paper surveys the landscape of actual and possible hybrid recommenders, and introduces a novel hybrid, EntreeC, a system that combines knowledge-based recommendation and collaborative filtering to recommend restaurants. Further, we show that semantic ratings obtained from the knowledge-based part of the system enhance the effectiveness of collaborative filtering.     

Analysis and Classification of Multi-Criteria Recommender Systems

Recent studies have indicated that the application of Multi-Criteria Decision Making (MCDM) methods in recommender systems has yet to be systematically explored. This observation partially contradicts with the fact that in related literature, there exist several contributions describing recommender systems that engage some MCDM method. Such systems, which we refer to as multi-criteria recommender systems, have early demonstrated the potential of applying MCDM methods to facilitate recommendation, in numerous application domains. On the other hand, a comprehensive analysis of existing systems would facilitate their understanding and development. Towards this direction, this paper identifies a set of dimensions that distinguish, describe and categorize multi-criteria recommender systems, based on existing taxonomies and categorizations. These dimensions are integrated into an overall framework that is used for the analysis and classification of a sample of existing multi-criteria recommender systems. The results provide a comprehensive overview of the ways current multi-criteria recommender systems support the decision of online users.     

考虑时间效应的矩阵分解技术在推荐系统中的应用

现实生活中,人们的喜好、观念往往随着时间的推移发生变化。人们对事物的看法,在不同的时间、场合也往往不同。即使是同一部电影,心情好的时候与心情坏的时候,给出的评价都不尽相同。因此,在推荐系统设计过程中,如何建立模型捕获这些动态的时间效应,给出更好的推荐结果,显得非常必要。     

Generalized Embedding Machines for Recommender Systems

Factorization machine(FM)is an effective model for feature-based recommendation that utilizes inner products to capture second-order feature interactions.However,one of the major drawbacks of FM is that it cannot capture complex high-order interaction signals.A common solution is to change the interaction function,such as stacking deep neural networks on the top level of FM.In this work,we propose an alternative approach to model high-order interaction signals at the embedding level,namely generalized embed-ding machine(GEM).The embedding used in GEM encodes not only the information from the feature itself but also the information from other correlated features.Under such a situation,the embedding becomes high-order.Then we can incorporate GEM with FM and even its advanced variants to perform feature interactions.More specifically,in this paper,we utilize graph convolution networks(GCN)to generate high-order embeddings.We integrate GEM with several FM-based models and conduct extensive experiments on two real-world datasets.The results demonstrate significant improvement of GEM over the corresponding baselines.     

Matrix Factorization Techniques for Recommender Systems

As the Netflix Prize competition has demonstrated, matrix factorization models are superior to classic nearest-neighbor techniques for producing product recommendations, allowing the incorporation of additional information such as implicit feedback, temporal effects, and confidence levels.     

基于度量学习的多空间推荐系统

隐式反馈具有数据获取成本小、形式广泛的特点,因此在现代推荐系统中被广泛使用.由于用户的隐式反馈通常是稀疏,不平衡,且含义不明确的.因此,想要准确学习用户和物品之间的复杂交互具有挑战性.传统的基于矩阵分解的推荐方法只能建模用户-物品之间的相似性.同时,矩阵分解使用点积运算作为相似度评估方式,而点积运算不满足三角不等式,即不能将用户-物品相似性传递到用户-用户以及物品-物品的相似性建模.因此,矩阵分解不足以在隐式反馈中充分建模用户和物品的关系.尽管现在有基于隐式反馈使用欧式距离来度量用户-物品相似度的度量学习方法,使得对应的推荐方法能够满足三角不等式.但是,现有的度量方法通常会将每个用户或者物品表示为度量空间中的单个点,进而在单个空间内通过用户-物品之间的距离来表征用户-物品之间的相似性.由于在不同的环境下,用户对于同一种类型的物品的偏好也可能存在差异.基于单个空间的用户、物品嵌入向量有可能无法满足用户具有的多种偏好和物品具有的多种属性,进而限制了推荐系统的性能.为了充分刻画用户和物品,我们尝试从多个侧面对于用户和物品进行表示,并提出了一个基于多空间的度量学习(MML)框架.通过设计整合多个空间相似性的度量方式,我们将用户和物品投影到多个空间中进行细粒度的表示.另外,我们设计了一种经过校准的优化策略,包括经过校准的最大间隔损失函数和经过校准的采样方法.在保持多空间度量学习表示能力的同时,确保框架的有效性.最后,模型通过训练好的用户、物品向量,对于稀疏的用户-物品交互矩阵进行填补.在动态更新空间权重的同时,可以赋予模型新的训练视角,最终实现端到端的训练.通过四个真实世界推荐数据集上进行的大量实验表明,MML可以在Recall和nDCG衡量指标上将目前最优的对比算法提高40%以上.     

PU Active Learning for Recommender Systems

Neural Processing Letters - In recommender systems, supervised information is usually obtained from the historical data of users. For example, if a user watched a movie, then the user-movie pair...     

基于位置的社会化网络推荐系统

近年来,基于位置的社会化网络推荐系统逐渐成为位置服务和社会网络分析的活跃课题之一.挖掘用户签到位置轨迹和社交活动数据,提取用户社会活动的地理空间特征模型及其与社会关系的关联性,设计合理的推荐算法,成为当前基于位置的社会化网络推荐系统的主要任务.该文从分析基于位置的社会化网络的结构特征人手,对基于位置的社会化网络推荐系统的基本框架、基于不同网络层次数据挖掘的推荐方法及应用类型等进行前沿概况、比较和分析.最后对有待深入研究的难点和热点进行分析和展望.     

Guest Editors' Introduction: Recommender Systems

This special issue presents eight articles, five long and three short, on techniques to improve recommender systems. They cover improving such aspects as user interaction with recommenders, the quality of results presented to users, and user trust in presented recommendations. This article is part of a special issue on Recommender Systems.