On improving aggregate recommendation diversity and novelty in folksonomy-based social systems

Benefit from technical advances in the Internet of Things, many social media applications relative to folksonomy have become ubiquitous. The size and complexity of folksonomy-based systems can unfortunately lead to information overload and reduced utility for users. Consequentially, the increasing need for recommender services from users has arisen. Many efforts have been made to address recommendation accuracy as well as other issues with respect to personalized recommendation in such systems. A key challenge facing these systems is that the most useful individual recommendations are to be found among diverse niche resources while increasing diversity most often compromises accuracy. In this paper, we introduce a simple yet elegant method-Diversity-aware Personalized PageRank (DaPPR)-to address this challenge from the aggregate perspective. DaPPR exploits a balance factor to adjust the influence of a personalized ranking vector and a unified non-personalized ranking vector based on PageRank. By this, it can reduce the impact of resource popularity on recommendations and then generate more diverse and novel recommendations to users. A hybrid DaPPR model that combines two ranking processes on the user-resource and the resource-tag bipartite graphs is specifically designed to meet the requirements in folksonomy-based systems. According to solid experiments, our proposed method yields better results balancing both aggregate accuracy and aggregate diversity (novelty). Improvements of all performance metrics are also obtained compared with the existing algorithms.