Inference methods
| Original link | http://yamlb.wordpress.com/2006/03/03/inference-methods/ |
| Date | 2006-03-03 |
| Status | publish |
List of inference methods I’ve heard about:
- Exact and numerical : reorganizing sum and products for exact inference on discrete variables (juction tree)
- Exact and analytical : using conjugate priors, posteriors can be analytically derived.
- Appoximation by sampling : All kind of sampling including the family of Markov chains Monte Carlo methods (Gibbs sampling seems to be often used)
- Approximation with variational approach: mean field, message passsing, belief propagation, (expectation propagation?). They consit in minimising a "distance" between the searched distribution with a member of a class of candidate distributions
- Approximations based on posterior modes : Laplace approximation, EM-related algorithms
Comments
- author: Yaroslav Bulatov
- date: 2006-03-07 09:10:51
Maybe you’ve seen this before, Wainwright shows a very cool way to derive message passing algorithms through variational approach http://research.microsoft.com/uai2004/Slides/Wainwright.pdf
- author: Pierre
- date: 2006-11-20 21:18:36
Some corrections/precisions:
Belief propagation is exact on trees (de-localization of computations), expectation propagation and variational method are similar in the sense they are both minimizing a KL divergence between the true posterior p and an approximate one (q).
But EP tries to (locally) minimize KL(p,q) and variational minimizes KL(q,p). This makes a difference, because the first leads to a “conservative”, “secure”, “inclusive” approximation, and variational results are too confident.
Mean Field is a simple variational method.
Also EM can be understood in the framework of variational approximation.
Loopy Belief propagation can be seen as a special case of EP with a fully factorized approximation family. There are also all those “free energy minimization” methods, Kikuchi approximation, Generalised belief propagation and Tree reweightseted BP stuff.
Ouf !!!