function cs = children(adj_mat, i, t)
% CHILDREN Return the indices of a node's children in sorted order
% c = children(adj_mat, i, t)
%
% t is an optional argument: if present, dag is assumed to be a 2-slice DBN

if nargin < 3 
  cs = find(adj_mat(i,:));
else
  if t==1
    cs = find(adj_mat(i,:));
  else
    ss = length(adj_mat)/2;
    j = i+ss;
    cs = find(adj_mat(j,:)) + (t-2)*ss;
  end
end