Mauch MIREX 2010

function [interface, persist, transient] = compute_interface_nodes(intra, inter)

% COMPUTE_INTERFACE_NODES Find the nodes in a DBN that represent a sufficient statistic

% [interface, persist, transient] = compute_interface_nodes(intra, inter)

%

% The interface nodes are all those that has an incoming temporal arc,

% or which are parents of such nodes.

% If the parents are in the previous slice, this just means they have an

% outgoing temporal arc.

% (The parents of nodes with incoming temporal arcs are needed

% because moralization will bring them into the clique.)

%

% The persisent nodes are all those that have one or more incoming temporal arc.

% The transient nodes are all the non-persistent.

%

% See U. Kjaerulff, "dHugin: A computational system for dynamic

% time-sliced Bayesian networks", Intl. J. Forecasting (11) 89-111, 1995

n = length(intra);

interface = [];

persist = [];

% any nodes with incoming arcs

for u=1:n

  if any(inter(:,u))

    interface = [interface u];

    persist = [persist u];

  end

end

% Any nodes which are parents of nodes with incoming arcs

for u=1:n

  cs = children(intra, u);

  if any(inter(:, cs))

    interface = [interface u];

  end

  %cs = children(inter, u);

  % if ~isempty(myintersect(cs, persist))

  %  interface = [interface u];

  %end

end

interface = unique(interface);

persist = unique(persist);

transient = mysetdiff(1:n, persist);