Four men are walking up a trail.
the men are outdoors
Having an unified group of four men can be shortened to the men.  The activity of walking up a trail can only be done outside a building which means the men are outdoors.
exists e1 s1 x1 x2.(a_up(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_trail(x2) & n_man(x1) & card_eq_4(x1))
exists p1 x1.(n_man(x1) & exists x2.((x1 = x2) & n_outdoors(x2)))