This boy is going down the slope on skis.
This boy is going up the slope in snowshoes.
A boy who is going down the slop cannot also be going up the slope. Skis are a different item than snowshoes.
exists e1 s1 x1 x2 x3.(n_slope(x2) & n_boy(x1) & a_down(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_go(e1) & on(x2,x3) & n_ski(x3))
exists e1 s1 x1 x2 x3.(n_slope(x2) & n_boy(x1) & in(e1,x3) & n_snowsho(x3) & a_up(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_go(e1))