Open thread, January 25- February 1

NancyLebovitz

If it's worth saying, but not worth its own post (even in Discussion), then it goes here.

I'm quite new to LW, and find myself wondering whether Hidden Markov models (HMM) are underappreciated as a formal reasoning tool in the rationalist community, especially compared to Bayesian networks?

Perhaps it's because HMM seem to be more difficult to grasp?

Or it's because formally HMM are just a special case of Bayesian networks (i.e. dynamic Bayes nets)? Still, HMM are widely used in science on their own.

For comparison, Google search "bayes OR bayesian network OR net" site:lesswrong.com gives 1,090 results.

Google search hidden markov model site:lesswrong.com gives 91 results.

Out of curiosity, did you happen to read Kurzweil's recent book on HHMMs?

I think the safest answer is that a HMM is just a specific way of mathematically writing down an updating Bayesian network.

2ChristianKl12y

Hidden Markov models are a reasoning model to solve a specific problem. If you don't face that specific problem they are no use. Most of the problems we discuss aren't modeled well with HMMs.

0Qiaochu_Yuan12y

There's a proliferation of terminology in this area; I think a lot of these are in some sense equivalent and/or special cases of each other. I guess "Bayesian network" is more consistent with the other Bayes-based vocabulary around here.