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A.P. de Vries

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Protecting Users as Big Multimedia Data Grows Bigger

Book chapter (2019) - Martha Larson, Jaeyoung Choi, Manel Slokom, Zekeriya Erkin, Gerald Friedland, Arjen P. de Vries
This chapter discusses the relationship between privacy and algorithms that make use of large amounts of multimedia data. As users continue to post their audiovisual content online, and as companies continue to collect user profiles and interaction data, concerns about privacy are becoming increasingly urgent. The chapter focuses on multimedia algorithms, but looks beyond a purely technical approach to privacy. It explains what must be done to protect users’ privacy. The chapter explores the particular privacy challenges raised by multimedia, and specifically by big multimedia data. It presents example techniques and algorithms. The chapter provides an outlook for the next steps for multimedia privacy research. It shows cybercasing as a motivating example in order to illustrate the importance of privacy. The chapter then focuses on personal information. Personal information that must be protected is referred to as sensitive information. ...
Conference paper (2017) - Benjamin Kille, Andreas Lommatzsch, Frank Hopfgartner, Martha Larson, Arjen P. de Vries
Recommender System research has evolved to focus on developing algorithms capable of high performance in online systems. This development calls for a new evaluation infrastructure that supports multi-dimensional evaluation of recommender systems. Today’s researchers should analyze algorithms with respect to a variety of aspects including predictive performance and scalability. Researchers need to subject algorithms to realistic conditions in online A/B tests. We introduce two resources supporting such evaluation methodologies: the new data set of stream recommendation interactions released for CLEF NewsREEL 2017, and the new Open Recommendation Platform (ORP). The data set allows researchers to study a stream recommendation problem closely by “replaying” it locally, and ORP makes it possible to take this evaluation “live” in a living lab scenario. Specifically, ORP allows researchers to deploy their algorithms in a live stream to carry out A/B tests. To our knowledge, NewsREEL is the first online news recommender system resource to be put at the disposal of the research community. In order to encourage others to develop comparable resources for a wide range of domains, we present a list of practical lessons learned in the development of the dataset and ORP. ...

Multi-dimensional evaluation of real-time stream-recommendation algorithms

Conference paper (2016) - Benjamin Kille, Andreas Lommatzsch, Gebrekirstos G Gebremeskel, Frank Hopfgartner, Martha Larson, Jonas Seiler, Davide Malagoli, András Serény, Torben Brodt, Arjen P De Vries
Successful news recommendation requires facing the challenges of dynamic item sets, contextual item relevance, and of fulfilling non-functional requirements, such as response time. The CLEF NewsREEL challenge is a campaign-style evaluation lab allowing participants to tackle news recommendation and to optimize and evaluate their recommender algorithms both online and offline. In this paper, we summarize the objectives and challenges of NewsREEL 2016. We cover two contrasting perspectives on the challenge: that of the operator (the business providing recommendations) and that of the challenge participant (the researchers developing recommender algorithms). In the intersection of these perspectives, new insights can be gained on how to effectively evaluate real-time stream recommendation algorithms. ...

Learning Personalized Ranking in a Semantic Space

Conference paper (2016) - Jeroen BP Vuurens, Martha Larson, Arjen P de Vries
Recommender systems leverage both content and user interactions to generate recommendations that fit users' preferences. The recent surge of interest in deep learning presents new opportunities for exploiting these two sources of information. To recommend items we propose to first learn a user-independent high-dimensional semantic space in which items are positioned according to their substitutability, and then learn a user-specific transformation function to transform this space into a ranking according to the user's past preferences. An advantage of the proposed architecture is that it can be used to effectively recommend items using either content that describes the items or user-item ratings. We show that this approach significantly outperforms state-of-the-art recommender systems on the MovieLens 1M dataset. ...
Conference paper (2016) - Jeroen BP Vuurens, Arjen P de Vries
First Story Detection (FSD) systems aim to identify those news articles that discuss an event that was not reported before. Recent work on FSD has focussed almost exclusively on efficiently detecting documents that are dissimilar from their nearest neighbor. We propose a novel FSD approach that is more effective, by adapting a recently proposed method for news summarization based on 3-nearest neighbor clustering. We show that this approach is more effective than a baseline that uses dissimilarity of an individual document from its nearest neighbor. ...
Conference paper (2006) - J Wang, AP de Vries, MJT Reinders
.Implicitacquisitionofuserpreferencesmakeslog-basedcollaborative¿lteringfavorableinpracticetoaccomplishrecommendations.Inthispaper,wefollowaformalapproachintextretrievaltore-formulatetheproblem.Basedontheclassicprobabilityrankingprinciple,weproposeaprobabilisticuser-itemrelevancemodel.Underthisformalmodel,weshowthatuser-basedanditem-basedapproachesareonlytwodi¿erentfactorizationswithdi¿erentindependenceassumptions.Moreover,weshowthatsmoothingisanimportantaspecttoestimatetheparametersofthemodelsduetodatasparsity.Byaddinglinearinterpolationsmoothing,theproposedmodelgivesaprobabilisticjusti¿cationofusingTF×IDF-likeitemrankingincollaborative¿ltering.Besidesgivingtheinsightunderstandingoftheproblemofcollaborative¿ltering,wealsoshowexperimentsinwhichtheproposedmethodprovidesabetterrecommendationperformanceonamusicplay-listdataset. ...