Here are some Hidden Markov Models (HMMs).
PlainHMM is the usual HMM:
q_1 ---> q_2 ---> q_3 ....
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v v v
o_1 o_2 o_3 ...
TwoOutputHMM has one hidden stream and two output streams:
a_1 a_2 a_3 ...
^ ^ ^
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q_1 ---> q_2 ---> q_3 ...
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v v v
o_1 o_2 o_3 ...
CoupledHMM has two hidden streams and two output streams:
a_1 a_2 a_3 ...
^ ^ ^
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p_1 -->_ p_2 -->_ p_3 ...
\ /| \ /|
\ / \ /
X X
/ \ / \
/ _\| / _\|
q_1 --> q_2 --> q_3 ...
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v v v
o_1 o_2 o_3 ...
This uses a modified version of mallet (included in the lib directory) whose source can be obtained
from:
https://bitbucket.org/jpate/mallet