function M = remove_unreachable(M)
% removes the unreachable states of M
% see str2dfsa.m for basic dfsa definitions
% see str2nfsa.m for basic nfsa definitions

R = reachable_states(M);
%R = union(R,[M.q0]);
M.Q = R;
M.F = intersect(M.F,R);
M = compact_names(M);
return