A child is playing in the street, doing a cartwheel.
A boy is doing a cartwheel to practice gymnastics.
A child is not always a boy. The purpose of doing a cartwheel would not always be to practice gymnastics.
exists e2 e1 x1 x2 x3.(n_street(x2) & for(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_do(e2) & n_cartwheel(x3) & in(e1,x2) & Actor(e1,x1) & v_play(e1) & n_child(x1))
exists e1 p1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & Topic(x2,p1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x2) & v_practice(e2) & n_gymnastics(x3)) & n_cartwheel(x2) & n_boy(x1))