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1 % Burglar alarm example
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2
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3 N = 5;
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4 dag = zeros(N,N);
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5 E = 1; B = 2; R = 3; A = 4; C = 5;
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6 dag(E,[R A]) = 1;
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7 dag(B,A) = 1;
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8 dag(A,C)=1;
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9
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10 % true = state 1, false = state 2
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11 ns = 2*ones(1,N); % binary nodes
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12 bnet = mk_bnet(dag, ns);
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13
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14 bnet.CPD{E} = tabular_CPD(bnet, E, [0.1 0.9]);
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15 bnet.CPD{B} = tabular_CPD(bnet, B, [0.01 0.99]);
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16 %bnet.CPD{R} = tabular_CPD(bnet, R, [0.65 0.00001 0.35 0.99999]);
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17 bnet.CPD{R} = tabular_CPD(bnet, R, [0.65 0.01 0.35 0.99]);
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18 bnet.CPD{A} = tabular_CPD(bnet, A, [0.95 0.8 0.3 0.001 0.05 0.2 0.7 0.999]);
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19 bnet.CPD{C} = tabular_CPD(bnet, C, [0.7 0.05 0.3 0.95]);
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20
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21
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22 engine = jtree_inf_engine(bnet);
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23 ev = cell(1,N);
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24 ev{C} = 1;
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25 engine = enter_evidence(engine, ev);
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26 mE = marginal_nodes(engine, E);
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27 mB = marginal_nodes(engine, B);
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28 fprintf('P(E|c)=%5.3f, P(B|c)=%5.3f\n', mE.T(1), mB.T(1))
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29
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30 ev{C} = 1;
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31 ev{R} = 1;
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32 engine = enter_evidence(engine, ev);
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33 mE = marginal_nodes(engine, E);
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34 mB = marginal_nodes(engine, B);
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35 fprintf('P(E|c,r)=%5.3f, P(B|c,r)=%5.3f\n', mE.T(1), mB.T(1))
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36
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37
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38 if 0
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39 nsamples = 100;
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40 samples = zeros(nsamples, 5);
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41 for i=1:nsamples
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42 samples(i,:) = cell2num(sample_bnet(bnet))';
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43 end
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44 end
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