A band is performing on stage.
A rock and roll band is playing music for a school dance.
band  doesn't always mean rock and roll
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 x5 x6 x7.(for(e1,x6) & n_dance(x6) & of(x6,x7) & n_school(x7) & Theme(e1,x5) & Actor(e1,x1) & v_play(e1) & n_music(x5) & n_band(x3) & of(x3,x4) & n_roll(x4) & n_rock(x2) & subset_of(x3,x1) & subset_of(x2,x1))