A boy on a water slide
A boy is near the water.
The boy would need to be near water in order to be on the water slide.
exists x1 x2 x3.(a_topic(x1) & on(x1,x2) & n_slide(x2) & of(x2,x3) & n_water(x3) & n_boy(x1))
exists p1 x1 x2.(n_water(x2) & near(x1,x2) & n_boy(x1))