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1 function [transprob, termprob] = remove_hhmm_end_state(A)
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2 % REMOVE_END_STATE Infer transition and termination probabilities from automaton with an end state
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3 % [transprob, termprob] = remove_end_state(A)
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4 %
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5 % A(i,k,j) = Pr( i->j | Qps=k), where i in 1:Q, j in 1:(Q+1), and Q+1 is the end state
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6 % This implements the equation in footnote 3 of my NIPS 01 paper,
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7 % transprob(i,k,j) = \tilde{A}_k(i,j)
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8 % termprob(k,j) = \tau_k(j)
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9 %
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10 % For the top level, the k index is missing.
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11
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12 Q = size(A,1);
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13 toplevel = (ndims(A)==2);
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14 if toplevel
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15 Qk = 1;
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16 A = reshape(A, [Q 1 Q+1]);
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17 else
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18 Qk = size(A, 2);
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19 end
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20
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21 transprob = A(:, :, 1:Q);
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22 term = A(:,:,Q+1)'; % term(k,j) = P(Qj -> end | k)
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23 termprob = term;
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24 %termprob = zeros(Qk, Q, 2);
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25 %termprob(:,:,2) = term;
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26 %termprob(:,:,1) = 1-term;
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27
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28 for k=1:Qk
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29 for i=1:Q
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30 for j=1:Q
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31 denom = (1-termprob(k,i));
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32 denom = denom + (denom==0)*eps;
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33 transprob(i,k,j) = transprob(i,k,j) / denom;
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34 end
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35 end
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36 end
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37
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38 if toplevel
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39 termprob = squeeze(termprob);
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40 transprob = squeeze(transprob);
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41 end
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