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1 function msg = tree_protocol(engine, evidence, msg)
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2
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3 bnet = bnet_from_engine(engine);
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4 N = length(bnet.dag);
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5
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6 % Send messages from leaves to root
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7 for i=1:N-1
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8 n = engine.postorder(i);
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9 above = parents(engine.adj_mat, n);
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10 msg = send_msgs_to_some_neighbors(n, msg, above, bnet, engine.child_index, engine.parent_index, ...
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11 engine.msg_type, evidence);
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12 end
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13
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14 % Process root
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15 n = engine.root;
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16 cs = children(bnet.dag, n);
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17 %msg{n}.lambda = compute_lambda(n, cs, msg, engine.msg_type);
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18 msg{n}.lambda = prod_lambda_msgs(n, cs, msg, engine.msg_type);
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19 ps = parents(bnet.dag, n);
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20 msg{n}.pi = CPD_to_pi(bnet.CPD{bnet.equiv_class(n)}, engine.msg_type, n, ps, msg, evidence);
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21
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22 % Send messages from root to leaves
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23 for i=1:N
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24 n = engine.preorder(i);
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25 below = children(engine.adj_mat, n);
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26 msg = send_msgs_to_some_neighbors(n, msg, below, bnet, engine.child_index, engine.parent_index, ...
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27 engine.msg_type, evidence);
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28 end
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29
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30
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31 %%%%%%%%%%
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32
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33 function msg = send_msgs_to_some_neighbors(n, msg, valid_nbrs, bnet, child_index, parent_index, ...
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34 msg_type, evidence)
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35
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36 verbose = 0;
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37
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38 ns = bnet.node_sizes;
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39 dag = bnet.dag;
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40 e = bnet.equiv_class(n);
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41 CPD = bnet.CPD{e};
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42
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43
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44 cs = children(dag, n);
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45 %msg{n}.lambda = compute_lambda(n, cs, msg);
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46 msg{n}.lambda = prod_lambda_msgs(n, cs, msg, msg_type);
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47 if verbose, fprintf('%d computes lambda\n', n); display(msg{n}.lambda); end
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48
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49 ps = parents(dag, n);
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50 msg{n}.pi = CPD_to_pi(CPD, msg_type, n, ps, msg, evidence);
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51 if verbose, fprintf('%d computes pi\n', n); display(msg{n}.pi); end
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52
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53 ps2 = myintersect(parents(dag, n), valid_nbrs);
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54 for p=ps2(:)'
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55 lam_msg = CPD_to_lambda_msg(CPD, msg_type, n, ps, msg, p, evidence);
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56 j = child_index{p}(n); % n is p's j'th child
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57 msg{p}.lambda_from_child{j} = lam_msg;
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58 if verbose, fprintf('%d sends lambda to %d\n', n, p); display(lam_msg); end
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59 end
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60
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61 cs2 = myintersect(cs, valid_nbrs);
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62 for c=cs2(:)'
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63 %pi_msg = compute_pi_msg(n, cs, msg, c);
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64 pi_msg = compute_bel(msg_type, msg{n}.pi, prod_lambda_msgs(n, cs, msg, msg_type, c));
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65 j = parent_index{c}(n); % n is c's j'th parent
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66 msg{c}.pi_from_parent{j} = pi_msg;
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67 if verbose, fprintf('%d sends pi to %d\n', n, c); display(pi_msg); end
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68 end
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69
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70
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71
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