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The use of Self-Organizing Maps in Recommender Systems: A survey of the Recommender Systems field and a presentation of a State of the Art Highly Interactive Visual Movie Recommender System
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
2006 (English)Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

“Is one’s entire psyche’s most secret landscape really a fairly public thing, given just a few pieces of information?” – Douglas R. Hofstadter

This is a thesis about recommender systems, and the different approaches recommender systems use to solve the information overload problem. Our focus lies on two common approaches, collaborative filtering and content based filtering. Both of these approaches have their weaknesses and strengths. To overcome the weaknesses of each approach, various hybrid filters have been developed. We will start by analyzing these three approaches based on previous research literature and will then proceed to implement different variants of these approaches, including our own filtering approach for the movie domain. These implementations will be done in Java and open sourced for further development by other researchers in this area. The results will be evaluated and compared against previous research in this area in order to validate our implementations. Evaluation will be done by using standard metrics that are commonly used for evaluating the accuracy of recommender systems.

Various algorithms from the machine learning community have been used in the effort to improve and solve some of the problems in the previously mentioned approaches. We will concentrate on one such algorithm, Kohonen’s self-organizing map algorithm. The self-organizing map algorithm is an unsupervised learning algorithm which we believe is suitable for recommender systems in the movie domain. Our implementation of this algorithm will be used together with collaborative filtering approaches in the effort of designing a recommender system for movies. The result of this approach will be evaluated and compared against the results from our previous implementations and discussed in the context of previous results from the recommender systems research community.

Evaluating the effectiveness of recommender systems is often done by analyzing the accuracy of the recommendations produced by the techniques used to implement the different approaches. However, the goal for a recommender system is not only to give accurate recommendations but also to conceive to the user trust and encourage the user to explore the recommendations. This is more of an interface issue than an algorithmic issue, we have chosen to call this the recommendation interface problem. Similar conclusions have been drawn by other researchers and different attempts to solve this has been done. We will summarize and discuss proposed solutions. We will introduce and describe what we call visual recommendations, and show how this approach solves the recommendation interface problem by creating a visual recommender system called MOVSOM.

The testing and evaluation will be done on the well used Movie Lens dataset, as well on a larger dataset taken from an e-commerce site selling DVDs, together with movie attributes provided by the IMDb.

Our empirical evaluation results shows that MOVSOM produces recommendations of movies that are comparable to state of the art techniques and with the combination of our solution to the recommendation interface problem we believe that this approach has a very promising future as are commender system for movies.

“I love deadlines. I like the whooshing sound they make as they fly by.” – Douglas Adams

Place, publisher, year, edition, pages
2006. , 192 p.
Keyword [en]
self-organizing maps, recommender system, movsom, the serendipity problem, visual recommendations, movie map
Keyword [sv]
rekommenderingssystem, visuella rekommenderingar, filmkarta, movsom
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-120029OAI: oai:DiVA.org:uu-120029DiVA: diva2:302239
Educational program
Master Programme in Computer Science
Available from: 2011-11-07 Created: 2010-03-05 Last updated: 2011-11-07Bibliographically approved

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