I just read about Linear dynamical systems and I already know HMM. I wonder if HMMs are a special case of LDS or are there good relations.

(Both were compared by Geoffrey Hinton in one of his lectures to Recurrent Neural Networks.)

Or are there other types of continuous HMM (where the internal state space is continuous)?

asked Oct 16 '13 at 11:27

Albert%20Zeyer's gravatar image

Albert Zeyer
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edited Oct 16 '13 at 11:30


2 Answers:

Yes. Given probabilities on the current state it's a linear operation to get probabilities on the next state, or the next emissions, if your output probabilities are linear.

answered Oct 16 '13 at 14:41

Alexandre%20Passos's gravatar image

Alexandre Passos ♦
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Just to add a bit to Alexandre great answer.

This can be extended to pretty much any Linear Gaussian System as well, that is, the case when the transition probabilities and the observation probabilities are both Gaussian (also called Kalman Filters)

There is a great paper by Roweis and Zoubin that extends on this to other things like PCA, Factor Analysis and Mixture of gaussians.

In the paper they unify all these models on the same basic premises.

As an historical anecdote, both HMM and Kalman Filters were discovered by different people in the 60s, but only until the 90s they were really unified.

answered Oct 17 '13 at 15:41

Leon%20Palafox's gravatar image

Leon Palafox ♦
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