A group of children prepare to perform.
Some old people play chess.
A group of children prepare to perform instead of old people playing chess.
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_prepare(e1) & exists e2.(Actor(e2,x1) & v_perform(e2)) & of(x1,x2) & n_child(x2) & n_group(x1))
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_chess(x2) & n_people(x1) & a_old(s1) & Theme(s1,x1))