Children on rollerblades are playing hockey indoors.
Nobody is playing.
If nobody is playing then it would be impossible for children to be playing there.
exists e1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_indoor(x3) & of(x3,x4) & n_hockey(x4) & on(x1,x2) & n_rollerblade(x2) & n_child(x1))
-exists e1 x1.(Actor(e1,x1) & v_play(e1) & n_person(x1))