Community-Enhanced Contrastive Learning for Graph Collaborative Filtering

Abstract

Graph collaborative filtering can efficiently find the hidden interests of users for recommender systems in recent years. This method can learn complex interactions between nodes in the graph, identify user preferences, and provide satisfactory recommendations. However, recommender systems face the challenge of data sparsity. To address this, recent studies have utilized contrastive learning to make use of unlabeled data structures. However, the existing positive and negative example sampling methods are not reasonable. Random-based or data augmentation-based sampling cannot make use of useful latent information. Clustering-based sampling methods ignore the semantics of node features and the relationship between global and local information. To utilize the latent structures in the data, we introduce a novel Community-Enhanced Contrastive Learning method to help the recommendation main task called CECL which uses a community detection algorithm to sample examples with semantic and global information, using both known and hidden community connections in the bipartite interaction graph. Extensive experiments are conducted on two well-known datasets, the results of which show a 12% and 8% performance improvement compared to that of the existing baseline methods.