Children ride a balloon ride in an amusement park.
The park was empty
The park cannot be empty if children ride a baloon ride at the same time.
exists e1 x1 x2 x3 x4 x5.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & in(x2,x4) & n_park(x4) & of(x4,x5) & n_amusement(x5) & n_ride(x2) & of(x2,x3) & n_balloon(x3) & n_child(x1))
exists s1 x1.(n_park(x1) & Theme(s1,x1) & a_empty(s1))