p_bar(x) = p(x,e)
p(x) is p(x|e)
p_bar is hard to estimate,
but p(x) is easy
and p(x) \propotion p_bar
q is easier for sampling, while we cant sample from p
Occam‘s Razor???
2018 10-708 (CMU) Probabilistic Graphical Models {Lecture 15} [Mean field Approximation]
原文：https://www.cnblogs.com/ecoflex/p/10259391.html