function DS = deadstates_fsa(M)
% DS are the "dead" states of the FSA M
DS = [];
for q=M.Q
  Mq = M;
  Mq.q0 = q;
  Mq = remove_unreachable(Mq);
  if empty_fsa(Mq)
    DS(end+1) = q;
  end
end
DS = setdiff(DS,M.q0); %q0 is always reachable
return