A skier is airborne in front of a tree.
A man is skiing down the mountain.
Skier does not imply man. Just because a skier is airborne does not mean he is skiing down the mountain.
exists s1 x1 x2 x3.(in(s1,x2) & of(x2,x3) & n_tree(x3) & n_front(x2) & Theme(s1,x1) & a_airborne(s1) & n_skier(x1))
exists e1 s1 x1 x2.(n_mountain(x2) & a_down(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_ski(e1) & n_man(x1))