A band is performing on stage.
The band is good.
performing doesn't always mean  good.
exists e1 x1 x2.(on(e1,x2) & n_stage(x2) & Actor(e1,x1) & v_perform(e1) & n_band(x1))
exists s1 x1.(n_band(x1) & Theme(s1,x1) & a_good(s1))