A man sitting on an empty train
A man is sitting on a train.
A train could be an empty train.
exists e1 s1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_train(x3) & a_empty(s1) & Theme(s1,x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1))