wolffd@0: function check_for_cd_arcs(onodes, cnodes, dag)
wolffd@0: % CHECK_FOR_CD_ARCS Raise an error if there are any C->D links where the C node is hidden.
wolffd@0: % check_for_cd_arcs(onodes, cnodes, dag)
wolffd@0: %
wolffd@0: % We cannot convert the logistic/softmax function (C->D CPD) to a Gaussian potential
wolffd@0: % unless we use the variational approximation discussed in 
wolffd@0: % "A variational approximation for Bayesian networks with discrete and continuous latent
wolffd@0: % variables", K. Murphy, UAI 1999.
wolffd@0: 
wolffd@0: n = length(dag);
wolffd@0: hnodes = mysetdiff(1:n, onodes);
wolffd@0: chid = myintersect(cnodes, hnodes);
wolffd@0: dnodes = mysetdiff(1:n, cnodes);
wolffd@0: for i=chid(:)'
wolffd@0:   dcs = myintersect(children(dag, i), dnodes);
wolffd@0:   if ~isempty(dcs)
wolffd@0:     error(['hidden cts node ' num2str(i) ' has a discrete child']);
wolffd@0:   end
wolffd@0: end
wolffd@0: 
wolffd@0: 
wolffd@0: 
wolffd@0: