A rock band is playing for a crowd.
No one is watching the band.
If no one is watching there cannot be a crowd.
exists e1 x1 x2 x3.(for(e1,x3) & n_crowd(x3) & Actor(e1,x1) & v_play(e1) & n_band(x1) & of(x1,x2) & n_rock(x2))
exists x2.(n_band(x2) & -exists e1 x1.(Theme(e1,x2) & Actor(e1,x1) & v_watch(e1) & n_one(x1)))