Enhancing guidance for missing data in diffusion-based sequential recommendation

TL;DR

This paper introduces CARD, a novel diffusion-based recommendation method that enhances guidance by focusing on interest-turning points in user sequences, effectively handling missing data and improving recommendation quality.

Contribution

CARD employs a dual-side Thompson Sampling and counterfactual attention to identify key interest points and suppress noise, advancing sequential recommendation with missing data.

Findings

Outperforms existing methods on real-world datasets

Effectively identifies interest-shift points in user sequences

Maintains computational efficiency

Abstract

Contemporary sequential recommendation methods are becoming more complex, shifting from classification to a diffusion-guided generative paradigm. However, the quality of guidance in the form of user information is often compromised by missing data in the observed sequences, leading to suboptimal generation quality. Existing methods address this by removing locally similar items, but overlook ``critical turning points'' in user interest, which are crucial for accurately predicting subsequent user intent. To address this, we propose a novel Counterfactual Attention Regulation Diffusion model (CARD), which focuses on amplifying the signal from key interest-turning-point items while concurrently identifying and suppressing noise within the user sequence. CARD consists of (1) a Dual-side Thompson Sampling method to identify sequences undergoing significant interest shift, and (2) a counterfactual attention mechanism for these sequences to quantify the importance of each item. In this manner, CARD provides the diffusion model with a high-quality guidance signal composed of dynamically re-weighted interaction vectors to enable effective generation. Experiments show our method works well on real-world data without being computationally expensive. Our code is available at https://github.com/yanqilong3321/CARD.