A group of musicians rehearsing.
They are playing music.
Musicians rehearsing means they are playing music.
exists e1 x1 x2 x3.(a_topic(x1) & Actor(e1,x3) & v_rehearse(e1) & (x1 = x3) & of(x1,x2) & n_musician(x2) & n_group(x1))
exists e1 x1 x2.(n_thing(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_music(x2))