function Aiijj = treetensor(T,A,ii,jj)
% the probability transition tensor
% from nodes ii to nodes jj

global m

lii = length(ii);
ljj = length(jj);

dimA = repmat([m],[1 lii+ljj]);
Aiijj = zeros(prod(dimA),1);

Dii = repmat([m],[1 lii]);
Djj = repmat([m],[1 ljj]);

for xi=1:prod(Dii)
  x = ind2coord(xi,Dii);
  for yi=1:prod(Djj)
    y = ind2coord(yi,Djj);
    p = 1;
    for vi = 1:length(jj)
      v = jj(vi);
      [u,ui] = parent(T,v,ii);
      p = p * A(u,v,y(vi),x(ui));
    end
    tind = coord2ind([y x],dimA);
    Aiijj(tind) = p;
  end
end
Aiijj = reshape(Aiijj,dimA);
return



function [u,ui] = parent(T,v,uu)
u = find(T(:,v));
ui = find(uu==u);
return