解决推荐系统中假负样本问题,提升模型对真实负样本的判断力。
Correct and Weight: A Simple Yet Effective Loss for Implicit Feedback Recommendation
- 通过校准负样本分布,更准确估计未交互项的真实负向概率。
- 动态重加权机制让模型更关注易判别的负样本,降低模糊样本惩罚。
- 无需复杂修改,可直接用于现有推荐模型,效果显著优于主流方法。
从隐式反馈中学习已成为现代推荐系统的标准范式,但该设置面临持续存在的假负样本挑战——未观察到的用户-物品交互并不一定代表负面偏好。本文提出一种新颖且理论严谨的损失函数,称为修正与加权(Corrected and Weighted, CW)损失,系统性地修正假负样本在训练目标中的影响。方法融合两项关键技术:首先,受正例-未标注学习启发,通过理论近似真实负样本分布(p⁻)来校准负样本采样过程,利用可观测的总体数据分布(p)和正向交互分布(p⁺)获得更准确的负样本概率估计;其次,引入动态重加权机制,根据模型当前预测强度调整每个负样本的重要性,促使模型在正样本与已确定的易判负样本间建立更大排序间隔,同时降低对可能为假负样本的不确定负样本的惩罚。该方法优势在于简洁高效,无需改变数据采样流程或增加大量计算开销,可广泛应用于各类现有推荐模型。在四个大规模稀疏基准数据集上的大量实验表明,所提方法在多种面向排序的指标上均一致且显著优于一系列先进损失函数。
原文摘要 · Abstract (English)
Learning from implicit feedback has become the standard paradigm for modern recommender systems. However, this setting is fraught with the persistent challenge of false negatives, where unobserved user-item interactions are not necessarily indicative of negative preference. To address this issue, this paper introduces a novel and principled loss function, named Corrected and Weighted (CW) loss, that systematically corrects for the impact of false negatives within the training objective. Our approach integrates two key techniques. First, inspired by Positive-Unlabeled learning, we debias the negative sampling process by re-calibrating the assumed negative distribution. By theoretically approximating the true negative distribution (p-) using the observable general data distribution (p) and the positive interaction distribution (p^+), our method provides a more accurate estimate of the likelihood that a sampled unlabeled item is truly negative. Second, we introduce a dynamic re-weighting mechanism that modulates the importance of each negative instance based on the model's current prediction. This scheme encourages the model to enforce a larger ranking margin between positive items and confidently predicted (i.e., easy) negative items, while simultaneously down-weighting the penalty on uncertain negatives that have a higher probability of being false negatives. A key advantage of our approach is its elegance and efficiency; it requires no complex modifications to the data sampling process or significant computational overhead, making it readily applicable to a wide array of existing recommendation models. Extensive experiments conducted on four large-scale, sparse benchmark datasets demonstrate the superiority of our proposed loss. The results show that our method consistently and significantly outperforms a suite of state-of-the-art loss functions across multiple ranking-oriented metrics.
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