The boy is playing basketball.
Jack is playing.
You can not infer his name is Jack.
exists e1 x1 x2.(n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_basketball(x2))
exists e1 x1.(ne_per_jack(x1) & Actor(e1,x1) & v_play(e1))