Two children sled riding down a hill.
Two children are sledding in the snow, racing down a hill
Riding down a hill does not imply racing.  Sledding is not necessarily done in the snow.
exists e1 p1 x1.(exists e2 s1 x2.(a_down(s1) & Manner(e2,s1) & Theme(e2,x2) & Actor(e2,x1) & v_ride(e2) & n_hill(x2)) & Topic(e1,p1) & Actor(e1,x1) & v_sled(e1) & n_child(x1) & card_eq_2(x1))
exists e1 e2 s1 x1 x2 x3.(n_snow(x2) & for(e1,e2) & a_down(s1) & Manner(e2,s1) & Theme(e2,x3) & Actor(e2,x1) & v_race(e2) & n_hill(x3) & in(e1,x2) & Actor(e1,x1) & v_sled(e1) & n_child(x1) & card_eq_2(x1))