An officer in a reflective vest stands at the front of his van with his dog.
An officer with a dog is wearing a vest and standing by his van.
In order for the officer to be standing at the front of his van, he must be by his van.
exists s1 x1 x2 x3 x4 x5 x6.(n_dog(x6) & of(x6,x4) & n_male(x4) & n_male(x4) & n_van(x5) & of(x5,x4) & n_front(x4) & a_topic(x1) & in(x1,x2) & at(x2,x4) & of(x4,x5) & with(x5,x6) & n_stand(x2) & of(x2,x3) & n_vest(x3) & a_reflective(s1) & Theme(s1,x2) & n_officer(x1))
exists e1 x1 x2 x3 x4 x5 x6.(Theme(e1,x3) & Actor(e1,x1) & v_wear(e1) & subset_of(x5,x3) & by(x5,x6) & n_van(x6) & of(x6,x1) & n_male(x1) & n_standing(x5) & subset_of(x4,x3) & n_vest(x4) & with(x1,x2) & n_dog(x2) & n_officer(x1))