two people walking in front of a building.
The people are walking.
Walking in front of a building is generalized by the phrase the people are walking.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_building(x4) & n_front(x3) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1.(n_people(x1) & Actor(e1,x1) & v_walk(e1))