Horting Hatches an Egg: A New Graph-Theoretic Approach to Collaborative Filtering

Charu C. Aggarwal, Joel L. Wolf, Kun-Lung Wu, Philip S. Yu

Abstract: This paper introduces a new and novel approach to ratingbased collaborative filtering. The new technique is most appropriate for e-commerce merchants offering one or more groups of relatively homogeneous items such as compact disks, videos, books, software and the like. In contrast with other known collaborative filtering techniques, the new algorithm is graph-theoretic, based on the twin new concepts of ho&rag and predictability. As is demonstrated in this paper, the technique is fast, scalable, accurate, and requires only a modest learning curve. It makes use of a hierarchical classification scheme in order to introduce context into the rating process, and uses so-called creative links in order to find surprising and atypical items to recommend, perhaps even items which cross the group boundaries. The new technique is one of the key engines of the Intelligent Recommendation Algorithm (IRA) project, now being developed at IBM Research. In addition to several other recommendation engines, IRA contains a situation analyzer to determine the most appropriate mix of engines for a particular e-commerce merchant, as well as an engine for optimizing the placement of advertisements.