Recovering masked feedback with neural models is a popular paradigm in
recommender systems. Seeing the success of diffusion models in solving
ill-posed inverse problems, we introduce a conditional diffusion framework for
collaborative filtering that iteratively reconstructs a user's hidden
preferences guided by its historical interactions. To better align with the
intrinsic characteristics of implicit feedback data, we implement forward
diffusion by applying synthetic smoothing filters to interaction signals on an
item-item graph. The resulting reverse diffusion can be interpreted as a
personalized process that gradually refines preference scores. Through graph
Fourier transform, we equivalently characterize this model as an anisotropic
Gaussian diffusion in the graph spectral domain, establishing both forward and
reverse formulations. Our model outperforms state-of-the-art methods by a large
margin on one dataset and yields competitive results on the others.

使用神经模型通过条件扩散框架来恢复掩盖的反馈，在隐式反馈数据上实现了前向扩散，利用图傅里叶变换在图谱域中等效地表征模型，并在一个数据集上大幅超越最先进的方法，并在其他数据集上获得有竞争力的结果。