g about an HMM is that the
hidden nodes are discrete, so the system can model arbitrary dynamics
-- providing, of course, that the hidden state space is large enough.)
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<p>
<img src="Figures/hmm3.gif">
<p>
We have "unrolled" the model for three "time slices" -- the structure and parameters are
assumed to repeat as the model is unrolled further.
Hence to specify a DBN, we need to
define the intra-slice topology (within a slice),
the inter-slice topology (between two slices),
as well as the parameters for 