Two people talking walk down the sidewalk.
Two people are riding bikes.
The two people can either be riding bikes or walking,
exists e1 e2 x1 x2 x3.(n_sidewalk(x3) & down(e2,x3) & Theme(e2,x1) & v_walk(e2) & Actor(e1,x2) & v_talk(e1) & (x1 = x2) & n_people(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))