Dogs pull a sled in the snow.
Dogs are pulling a sled in a dog-sled competition.
Dogs pulling a sled in the snow does not necessarily imply that they are pulling s sled in a dog-sled competition.
exists e1 x1 x2 x3.(n_snow(x3) & Theme(e1,x2) & Actor(e1,x1) & v_pull(e1) & in(x2,x3) & n_sled(x2) & n_dog(x1))
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_pull(e1) & in(x2,x3) & n_competition(x3) & a_dog-sled(s1) & Theme(s1,x3) & n_sled(x2) & n_dog(x1))