Workers are cleaning railroad tracks.
People are working today.
The workers may be robots and not people.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_clean(e1) & n_track(x2) & of(x2,x3) & n_railroad(x3) & n_worker(x1))
exists e1 x1 x2.(Time(e1,x2) & n_today(x2) & Actor(e1,x1) & v_work(e1) & n_people(x1))