A band is playing at an outdoor music festival.
No band music in party
The band cannot be playing if there is no music
exists e1 s1 x1 x2 x3.(at(e1,x2) & n_festival(x2) & of(x2,x3) & n_music(x3) & a_outdoor(s1) & Theme(s1,x2) & Actor(e1,x1) & v_play(e1) & n_band(x1))
-exists x1 x2 x3.(a_topic(x1) & in(x1,x3) & n_party(x3) & n_music(x1) & of(x1,x2) & n_band(x2))