Variational methods are widely used for approximate posterior inference. However, their use is typically limited to families of distributions that enjoy particular conjugacy properties. To circumvent this limitation, we propose a family of variational approximations inspired by nonparametric kernel density estimation. The locations of these kernels and their bandwidth are treated as variational parameters and optimized to improve an approximate lower bound on the marginal likelihood of the data. Using multiple kernels allows the approximation to capture multiple modes of the posterior, unlike most other variational approximations. We demonstrate the efficacy of the nonparametric approximation with a hierarchical logistic regression model and a nonlinear matrix factorization model. We obtain predictive performance as good as or better than more specialized variational methods and sample-based approximations. The method is easy to apply to more general graphical models for which standard variational methods are difficult to derive.

本文提出了一种基于非参数核密度估计的变分逼近方法，通过优化内核位置和带宽参数最大化数据边际似然下限，不同于其他变分逼近方法，本方法能够捕捉后验分布的多个模式，并成功应用于各种图模型和非线性矩阵分解模型中，预测性能优于更专业化的变分方法和基于样本的逼近方法。

非参数变分推断