A band is performing on stage.
a group of people playing music
The band might not be playing music. They might be singing.
exists e1 x1 x2.(on(e1,x2) & n_stage(x2) & Actor(e1,x1) & v_perform(e1) & n_band(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & of(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_play(e1) & n_music(x4) & (x2 = x3) & n_people(x2) & n_group(x1))