Two men walking down a dirt path.
two people are riding bikes
You cannot be walking while riding a bike it is impossible.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & a_down(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_walk(e1) & n_path(x3) & of(x3,x4) & n_dirt(x4) & (x1 = x2) & n_man(x1) & card_eq_2(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_people(x1) & card_eq_2(x1))