Zahra Farahi - School of Engineering Science, College of Engineering, University of Tehran
Ali Moeini - School of Engineering Science, College of Engineering, University of Tehran
Ali Kamandi - School of Engineering Science, College of Engineering, University of Tehran Tehran, Iran
Mahmood Shabankhah - School of Engineering Science, College of Engineering, University of Tehran

In this paper, we focus on improving the performance of recommender systems. To do this, we propose a new algorithm named PBloofI which is a kind of hierarchical bloom filter. Actually, the Bloom filter is an array-based technique for showing the items’ features. Since the feature vectors of items are sparse, the Bloom filter reduces the space usage by using the hashing technique. And also, to reduce the time complexity we used the hierarchical version of bloom filter which is based on B+ tree of order d. Since Bloom filters can make a tradeoff between space and time, proposing a new hierarchical Bloom filter causes a remarkable reduction in space and time complexity of recommender systems. To increase the accuracy of the recommender systems we use Probabilistic version of hierarchical Bloom filter. By measuring the accuracy of the algorithm we show that the proposed algorithms not only decrease the time complexity but also have no significant effect on accuracy.

Recommender systems, Bloom Filter, Hierarchical Bloom filter