Decoupled Side Information Fusion for Sequential Recommendation

TL;DR

This paper introduces DIF-SR, a novel method for sequential recommendation that decouples side information from input to attention layers, enabling higher-rank attention matrices and improved modeling capacity, leading to better performance.

Contribution

The paper proposes a decoupled side information fusion approach that moves side information to the attention layer, enhancing expressiveness and flexibility in sequential recommendation models.

Findings

Outperforms state-of-the-art SR models on four datasets.

Allows higher-rank attention matrices for better information modeling.

Easily integrates into existing attention-based SR models.

Abstract

Side information fusion for sequential recommendation (SR) aims to effectively leverage various side information to enhance the performance of next-item prediction. Most state-of-the-art methods build on self-attention networks and focus on exploring various solutions to integrate the item embedding and side information embeddings before the attention layer. However, our analysis shows that the early integration of various types of embeddings limits the expressiveness of attention matrices due to a rank bottleneck and constrains the flexibility of gradients. Also, it involves mixed correlations among the different heterogeneous information resources, which brings extra disturbance to attention calculation. Motivated by this, we propose Decoupled Side Information Fusion for Sequential Recommendation (DIF-SR), which moves the side information from the input to the attention layer and decouples the attention calculation of various side information and item representation. We theoretically and empirically show that the proposed solution allows higher-rank attention matrices and flexible gradients to enhance the modeling capacity of side information fusion. Also, auxiliary attribute predictors are proposed to further activate the beneficial interaction between side information and item representation learning. Extensive experiments on four real-world datasets demonstrate that our proposed solution stably outperforms state-of-the-art SR models. Further studies show that our proposed solution can be readily incorporated into current attention-based SR models and significantly boost performance. Our source code is available at https://github.com/AIM-SE/DIF-SR.