function kf = list_kfollowers(A,q,k)
init_kfol(A,k);
kf = list_kfollowers_rec(A,q,k);
return

function kf = list_kfollowers_rec(A,q,k)
global KFOL
% KFOL{q,k} are the k-followers of q
if ~isequal(KFOL{q,k+1},{-1})
  % already computed this value
  kf = KFOL{q,k+1};
else
  kf = {};
  [qq1,ss1] = get_ndelta(A,q);
  for i=1:length(qq1)
    R = qq1{i};
    for r=R
      kf1 = list_kfollowers_rec(A,r,k-1);
      for j=1:length(kf1)
        kf1{j} = [ss1(i) kf1{j}];
      end
      kf = [kf kf1];
    end
  end
  kf = unique(kf);
  KFOL{q,k+1} = kf;
end
return


function init_kfol(A,K)
global KFOL
% KFOL{q,k} are the k-followers of q
KFOL = {};
for q=A.Q
  KFOL{q,1} = {''};
  for k=2:K+1
    KFOL{q,k} = {-1};
  end
end
return




function kf = list_kfollowers_old(A,q,k)
% lists all the k-followers of q in A
% conceptually simple but terribly wasteful -- do not use

kf = {};
if (k==0)
  kf{end+1} = '';
else
  [qq1,ss1] = get_ndelta(A,q);
  for i=1:length(qq1)
    R = qq1{i};
    for r=R
      kf1 = list_kfollowers(A,r,k-1);
      for j=1:length(kf1)
        kf1{j} = [ss1(i) kf1{j}];
      end
      kf = [kf kf1];
    end
  end
end
kf = unique(kf);
return