A man plays ball with a little boy.
a man and his son playing
We don't know that the little boy is his son.
exists e1 s1 x1 x2 x3.(with(e1,x3) & n_boy(x3) & a_little(s1) & Theme(s1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_ball(x2) & n_man(x1))
exists e1 s1 x1 x2 x3.(a_topic(s1) & subset_of(x2,s1) & Actor(e1,x3) & v_playing(e1) & (x2 = x3) & n_son(x2) & of(x2,x1) & n_male(x1) & subset_of(x1,s1) & n_man(x1))