matthiasm@8: function check_for_cd_arcs(onodes, cnodes, dag)
matthiasm@8: % CHECK_FOR_CD_ARCS Raise an error if there are any C->D links where the C node is hidden.
matthiasm@8: % check_for_cd_arcs(onodes, cnodes, dag)
matthiasm@8: %
matthiasm@8: % We cannot convert the logistic/softmax function (C->D CPD) to a Gaussian potential
matthiasm@8: % unless we use the variational approximation discussed in 
matthiasm@8: % "A variational approximation for Bayesian networks with discrete and continuous latent
matthiasm@8: % variables", K. Murphy, UAI 1999.
matthiasm@8: 
matthiasm@8: n = length(dag);
matthiasm@8: hnodes = mysetdiff(1:n, onodes);
matthiasm@8: chid = myintersect(cnodes, hnodes);
matthiasm@8: dnodes = mysetdiff(1:n, cnodes);
matthiasm@8: for i=chid(:)'
matthiasm@8:   dcs = myintersect(children(dag, i), dnodes);
matthiasm@8:   if ~isempty(dcs)
matthiasm@8:     error(['hidden cts node ' num2str(i) ' has a discrete child']);
matthiasm@8:   end
matthiasm@8: end
matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: