A child is enjoying the ducks on a fall day.
A boy is playing
Child doesn't imply boy. Just because a child is enjoying doesn't necessarily mean that the child is playing.
exists e1 x1 x2 x3 x4.(n_duck(x2) & on(e1,x3) & n_day(x3) & of(x3,x4) & n_fall(x4) & Theme(e1,x2) & Actor(e1,x1) & v_enjoy(e1) & n_child(x1))
exists e1 x1.(Actor(e1,x1) & v_play(e1) & n_boy(x1))