A sled and dogs mushing
dogs pull a sled
Mushing requires dogs to pull a sled.
exists e1 s1 x1 x2.(a_topic(x1) & Actor(e1,x2) & v_mush(e1) & (x1 = x2) & n_dog(x1) & a_sled(s1) & Theme(s1,x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_pull(e1) & n_sled(x2) & n_dog(x1))