“…Stein's method [5] provides an elegant probabilistic tool for comparing distributions based on Stein operators acting on a broad class of test functions, which has been used to tackle various problems in statistical inference, random graph theory, and computational biology. Modern machine learning tasks, such as density estimations [29,47,57], model criticisms [34,48,55], or generative modellings [20,40], may extensively involve the modelling and learning with intractable densities, where the normalisation constant (or partition function) is unable to be obtained in closed form. Stein operators may only require access to the distributions through the differential (or difference) of the log density functions (or mass functions), which avoids the knowledge of the normalisation constant.…”