In the domain of recommendations, previous works often retrieve items through sampling strategies from the database to gather negative signals for exploring implicit feedback. However, because of extremely sparse records, the existing items used as negative samples may not sufficiently support the interacted items in depicting the diverse interests of users. Consequently, the generation of negative samples needs to be explored in recommendation systems. In this study, we propose an interest-disentangled contrastive sample generation (IDCG) model to enhance interest modeling by contrasting interacted items with the generated samples for recommendation. Specifically, we decouple the interacted items of users into positively relevant and irrelevant factors of interest, providing a valuable clue to learn negatively relevant factors in personalized interests. Then, negative samples are generated by merging the learned negatively relevant factors and irrelevant factors. At this point, a two-level contrast is constructed between positive and negative samples and between the relevant factors of positives and negatives, providing auxiliary collaborative signals to debias and alleviate the interaction sparsity issue. Extensive experiments on three real datasets demonstrate the effectiveness of IDCG in generating targeted and meaningful negative samples from the perspective of disentangling relevant factors to promote interest modeling for recommendation.

Previous recommendation models build interest embeddings heavily relying on the observed interactions and optimize the embeddings with a contrast between the interactions and randomly sampled negative instances. To our knowledge, the negative interest signals remain unexplored in interest encoding, which merely serves losses for backpropagation. Besides, the sparse undifferentiated interactions inherently bring implicit bias in revealing users’ interests, leading to suboptimal interest prediction. The negative interest signals would be a piece of promising evidence to support detailed interest modeling. In this work, we propose a perturbed graph contrastive learning with negative propagation (PCNP) for recommendation, which introduces negative interest to assist interest modeling in a contrastive learning (CL) architecture. An auxiliary channel of negative interest learning generates a contrastive graph by negative sampling and propagates complementary embeddings of users and items to encode negative signals. The proposed PCNP contrasts positive and negative embeddings to promote interest modeling for recommendation. Extensive experiments demonstrate the capability of PCNP using two-level CL to alleviate interaction sparsity and bias issues for recommendation.

Previous works build interest learning via mining deeply on interactions. However, the interactions come incomplete and insufficient to support interest modeling, even bringing severe bias into recommendations. To address the interaction sparsity and the consequent bias challenges, we propose a graph contrastive learning on complementary embedding (GCCE), which introduces negative interests to assist positive interests of interactions for interest modeling. To embed interest, we design a perturbed graph convolution by preventing embedding distribution from bias. Since negative samples are not available in the general scenario of implicit feedback, we elaborate a complementary embedding generation to depict users’ negative interests. Finally, we develop a new contrastive task to contrastively learn from the positive and negative interests to promote recommendation. We validate the effectiveness of GCCE on two real datasets, where it outperforms the state-of-the-art models for recommendation.