A safety worker is checking the railway.
A person is working.
A safety worker is a person while checking the railway is working.
exists e1 x1 x2 x3.(n_railway(x3) & Theme(e1,x3) & Actor(e1,x1) & v_check(e1) & n_worker(x1) & of(x1,x2) & n_safety(x2))
exists e1 x1.(Actor(e1,x1) & v_work(e1) & n_person(x1))