A boy is doing a trick on his skateboard in a park.
The skate park is empty
If the boy is at the park, then it cannot simultaneously be empty
exists e1 x1 x2 x3 x4.(in(e1,x4) & n_park(x4) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & on(x2,x3) & n_skateboard(x3) & of(x3,x1) & n_male(x1) & n_trick(x2) & n_boy(x1))
exists s1 x1 x2.(n_park(x1) & of(x1,x2) & n_skate(x2) & Theme(s1,x1) & a_empty(s1))