The brown dog is standing next to a ball on the beach.
A brown dog stands at the beach.
at is almost the same as  on
exists e1 s1 x1 x2 x3.(n_beach(x3) & n_dog(x1) & a_brown(s1) & Theme(s1,x1) & on(e1,x3) & to(e1,x2) & n_ball(x2) & r_next(e1) & Actor(e1,x1) & v_stand(e1))
exists s1 x1 x2 x3.(n_beach(x3) & a_topic(x1) & at(x1,x3) & n_stand(x1) & of(x1,x2) & n_dog(x2) & a_brown(s1) & Theme(s1,x1))