  We reinterpreting the variational inference in a new perspective. Via this
way, we can easily prove that EM algorithm, VAE, GAN, AAE, ALI(BiGAN) are all
special cases of variational inference. The proof also reveals the loss of
standard GAN is incomplete and it explains why we need to train GAN cautiously.
From that, we find out a regularization term to improve stability of GAN
training.
