A boy is playing outside.
A boy plays with a ball outside.
You can not infer he plays with a ball.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_outside(x2) & n_boy(x1))
exists e1 x1 x2 x3.(with(e1,x2) & n_outside(x2) & of(x2,x3) & n_ball(x3) & Actor(e1,x1) & v_play(e1) & n_boy(x1))