A person is playing a drum.
Nobody is playing the drumset.
A person cannot be playing a dream if nobody is playing.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_drum(x2) & n_person(x1))
exists x2.(n_drumset(x2) & -exists e1 x1.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_person(x1)))