A Boy walking wearing a uniform.
Nobody is walking.
A boy walking cannot be nobody.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_wear(e1) & n_uniform(x4) & (x1 = x3) & n_walking(x1) & (x1 = x2) & ne_org_boy(x2))
-exists e1 x1.(Actor(e1,x1) & v_walk(e1) & n_person(x1))