Neighborhood-Restricted Mining and Weighted Application of Association Rules for Recommenders

Association rule mining algorithms such as Apriori were originally developed to automatically detect patterns in sales transactions and were later on also successfully applied to build collaborative filtering recommender systems (RS). Such rule mining-based RS not only share the advantages of other model-based systems such as scalability or robustness against different attack models, but also have the advantages that their recommendations are based on a set of comprehensible rules. In recent years, several improvements to the original Apriori rule mining scheme have been proposed that for example address the problem of finding rules for rare items. In this paper, we first evaluate the accuracy of predictions when using the recent IMSApriori algorithm that relies on multiple minimum-support values instead of one global threshold. In addition, we propose a new recommendation method that determines personalized rule sets for each user based on his neighborhood using IMSApriori and at recommendation time combines these personalized rule sets with the neighbors’ rule sets to generate item proposals. The evaluation of the new method on common collaborative filtering data sets shows that our method outperforms both a standard IMSApriori recommender and a nearest-neighbor baseline method. The observed improvements in predictive accuracy are particularly strong for sparse data sets.