function Ar = rev_fsa(A)
% Ar is the reverse fsa of A
% both are of type nfsa


if empty_fsa(A)
  % degenerate special case
  Ar = A;
  return
end


% make a new initial state, which epsilon-transitions
% to the final states of A

nq = length(A.Q);
Ar.Q = 1:(nq+1);
Ar.q0 = nq+1;
Ar.F = [A.q0];
Ar.ALF = A.ALF;

Ar = init_ndelta(Ar);

%for q=A.F
  Ar = set_ndelta(Ar,Ar.q0,repmat(['@'],length(A.F),1),{A.F});
%end

for q=A.Q
  [pp,ss] = get_ndparents(A,q);
  us = unique(ss);
  for s=us
    x = find(ss==s);
    R = pp(x);
    Ar = set_ndelta(Ar,[q],[s],{R});
  end
end

Ar = prune_eps(Ar);
Ar = remove_unreachable(Ar);

return